MK262 clone 77Grain 5.56 load problems / updated OCW tests

[Rprecision]

So I started off with a goal of building a 77 grain 5.56 load capable of 1moa for my new project. It’s an 18” Noveske SPR Suppressed.

Well, that’s where I started and it seems I am still there…

In a perfect world, or rather normal world, I would have a number of choices for components. Spending the past eight months I collected:

-1K once fired mixed brass
-1K FGMM SM Rifle Primers
-1K Nosler 77 Grain CC Match Bullets
-8lbs of Ramshot Tac

After some research I started my loads at standard length with 24.0 Tac. The first 10 rounds of this showed promise, which followed with another 10 rounds. This load was shot at around 40 degrees initially so I was concerned about loading up a bunch until further testing could commence. Pressure signs were there with a slightly flattened primer. No obvious swipes were found. My concerns were that higher ambient temps would cause pressures to rise.



The best 5 shot group came in with a Average MV at 2682 FPS.



Mid Spring I tested 10 rounds loaded at 24.4 Grains of Tac. Pressure signs were expectedly more pronounced and the accuracy dropped off. Compared side by side with 24.0 the choice seemed obvious. While I netted another 40-50 FPS it didn’t matter because it didn’t shoot.



I loaded 50 Rounds for further testing with 24.0 Tac.

This brings us to several weeks ago where on a hell of hot day I had a chance to put that 24.0 load to test. 101 Degrees, and I let it bake in the sun for a while. This was shot under much different conditions and POI changed about a 1” high 1” right. 10 rounds fired, 3 X 3 shot groups with a single cold clean bore starting it off. It didn’t set the world on fire but met my goals with one of the groups falling right in well under ½ MOA. Pressures were similar to that seen before, velocities were also very close to before.





So a few days ago I decided to take out the steel and shoot 2 X 5 shot groups at 200 yards. Here’s the results…………. Basically a overgrown 4” group netting 2MOA. It was windy 10-15mph, with .4 mil held for wind, but even at that this sucks.





Where do you think I should go from here? I still have another 30 or so loaded up at 24.0. Going back through the targets so far the load has produced some good groups but not very consistently. This is mixed brass, I understood that going into this venture. I just don’t know how much there is to be gained separating the brass out by head stamp. There is a good portion of WC, FC, LC and Nato.


The reality is I can’t develop a load for each head stamp, I just don’t have the resources for that. If I did, well I would have bought a single lot of LC but they just cant be had.

I accept some variations from mixed brass but I feel like I am back at square one

 

[Temp9]

I would say definitely sort by head stamp. Pick whichever brass you have the most of, and run with it. Maybe sell or trade the others. Regardless, I recommend not running mixed head stamps in precision rifles. At the very least, cull out the FC. I know Black Hills uses both WCC and LC in their remanufactured, and it seems to shoot just fine.

You're pretty much always going to see flattened primers in .223 using FGMM. At least I do. No biggie.

Next step is to post a picture of the rifle. Can't leave us hanging like that....

Then perform a proper OCW test and fine tune with at least two 5-shot groups per each potential OCW load.

Ramshot TAC is supposedly fairly temperature stable, but not amazingly so. I prefer AR-Comp for .223, but good luck finding any. I have a few pounds of TAC, as well, but I haven't gotten around to testing it, yet.

 

[6.5x47]

Did nearly what you did back in '03/04 when we were waiting for the first Blk Hills ammo to come available. Used the Hornady 75 bthp match in my 16" RRA with 1:9 twist. Tried 748, Varget, Tac, H4895 and a few others I'm forgetting. Used the older nickle plated Win SR primers to stand up to the pressures I was headed towards. I mic'd my LC 01/02/03 case heads with a 1" micrometer to the nearest .001". Would stop adding powder when the case head would expand more than .001". TAC gave me the fastest but H4895 gave me 2750 with 10 shots going into 10" @ 600 yds with a 2x ACOG for optics. I also roll a cannulure on the bullets with the CH Cannelure tool to help facilitate the bullet breaking up upon impact and for the Lee crimp die to force the case mouth to crimp into the cannelure.

Bad news. I sold that rifle in January and just took delivery of my new Sword International Mk 15. Have to now start new Mk 262 load development with factory cannelures Sierra 77 MK's.

Alan

 

[TheGerman]

Your spread is mostly vertical which points to a velocity differential. The 10 measurements you have listed on that piece of paper have a 83fps spread between the high/low values; this is not good and is what I believe to be your problem but can be fixed with loading the same brass. Most guys can get the standard deviation for a string of 10 to under 15 FPS.

I know its a pain to buy brass, but if you want to play this game correctly its what you have to do or you're going to continue burning powder.

 

[Rprecision]

Ok, its obvious I need a more uniform lot of brass, I knew that I just didnt want to admit it.

Does it matter what lot of LC it is ? I.E. what number is listed on the headstamp or can that be mixed without ill results

Any suggestions where to get a good lot of 1k Lake City Brass. I like to support folks on here if possible

 

[TheGerman]

Ok, its obvious I need a more uniform lot of brass, I knew that I just didnt want to admit it.

Does it matter what lot of LC it is ? I.E. what number is listed on the headstamp or can that be mixed without ill results

Any suggestions where to get a good lot of 1k Lake City Brass. I like to support folks on here if possible

I have NATO LC brass from all sorts of years and have never noticed a difference in them or the water capacity they hold. Some are just harder to get the primer crimp out than others for some odd reason.

If you're looking for brass, simply post a WTB thread. I used to get 1k brass for $55ish/shipped before the panic. Prices have risen a bit but I think most of the people that started charging insane prices for brass have gotten the memo. Depends how much you want to spend; I know someone asking 125ish per K, but I'd hold out for what you want to ay as prices are going back to normal.

 

[gunsnjeeps]

I'd start by sorting headstamps by maker. LC and WCC are consistant enough year to year. 24.8 is a max load. I'm not sure what your velocity loss in an 18 inch barrel is, I'd guess 40-50 fps. In my 20 inch barrel I get 2750 out of M262. Other questions; On a white steel plate where is your aiming point? Bipod, bags, sling?

 

[BC 6.8]

I have seen similar MV and ES with my 5.56 load of 24.3 gr Reloader 15/75 gr Hornady HPBTs. I shoot a 18" Black Hole Weaponry barrel on a Stag upper, but I sort my brass by headstamp which is mostly LC and Hornady. I have also seen higher velocity with increased temperature 2678 fps at 56° and 2699 fps at 82°. I have gotten up to 2715 fps average with 24.5 gr Re15, but my accuracy is better with the slightly lower velocity.

 

[Paladin2147]

Until you sort your brass, you are really not going to learn anything. Well except mixed brass sucks. Now you know that - move on.

 

[Rprecision]

I have NATO LC brass from all sorts of years and have never noticed a difference in them or the water capacity they hold. Some are just harder to get the primer crimp out than others for some odd reason.

If you're looking for brass, simply post a WTB thread. I used to get 1k brass for $55ish/shipped before the panic. Prices have risen a bit but I think most of the people that started charging insane prices for brass have gotten the memo. Depends how much you want to spend; I know someone asking 125ish per K, but I'd hold out for what you want to ay as prices are going back to normal.

I think I may just sort what I have and see where that puts me. Your right, this whole inflated ammo/firearms bubble has got to burst at some point.

I have seen similar MV and ES with my 5.56 load of 24.3 gr Reloader 15/75 gr Hornady HPBTs. I shoot a 18" Black Hole Weaponry barrel on a Stag upper, but I sort my brass by headstamp which is mostly LC and Hornady. I have also seen higher velocity with increased temperature 2678 fps at 56° and 2699 fps at 82°. I have gotten up to 2715 fps average with 24.5 gr Re15, but my accuracy is better with the slightly lower velocity.

The 75's were on the "to try" list before madness started

Until you sort your brass, you are really not going to learn anything. Well except mixed brass sucks. Now you know that - move on.

Dumb ass right ? I mean I sort my bolt gun brass why didnt it sink in the same rules apply to Semi

I'd start by sorting headstamps by maker. LC and WCC are consistant enough year to year. 24.8 is a max load. I'm not sure what your velocity loss in an 18 inch barrel is, I'd guess 40-50 fps. In my 20 inch barrel I get 2750 out of M262. Other questions; On a white steel plate where is your aiming point? Bipod, bags, sling?

Just so I am clear on this everyone. Is mixing LC and WCC brass acceptable ? or is it preffered to sort it all the way down to just LC.

It was shot off a Bipod bagged up prone with no sling. The Mil based scope alows the plate to be bracketed. However, your right a more defined aiming point should help.

Thanks for all the replies I will have to shoot some pictures of the rifle next time out

 

[gunsnjeeps]

I mostly load WCC brass from M262 shot during across the course service rifle matches. I haven't seen a difference in it from year to year if I mix production years, for example WCC 06 and 07. I've even shot some non M262 WCC and stayed in the same group. I have loaded and shot LC and PMC cases also. I have had POI changes between cases but generally cases from the same maker are consistant enough to sort by maker. I've picked up plenty of PMC brass (500 plus cases over a year) and used it for 100 yard matches with 52 grain SMK's. In the few boxes of Black Hills remanufactured ammo I've had they were loaded in the same cases (Lake City I think)by maker but mixed year. Thre's nothing wrong with loading different headstamps but mixing them in the same group can open up the group.

Looking at your group it looks almost like you have a high group and a low group that could be ammo, breathing/position, or drifting aim point (focus). To be honest I'm just getting into scoped rifles. I've shot Service Rifle since 98, some of it crosses over but bags and bipods are a little less familiar. (I still shoot prone with a sling to test ammo as I get better groups.)

 

[Rprecision]

I mostly load WCC brass from M262 shot during across the course service rifle matches. I haven't seen a difference in it from year to year if I mix production years, for example WCC 06 and 07. I've even shot some non M262 WCC and stayed in the same group. I have loaded and shot LC and PMC cases also. I have had POI changes between cases but generally cases from the same maker are consistant enough to sort by maker. I've picked up plenty of PMC brass (500 plus cases over a year) and used it for 100 yard matches with 52 grain SMK's. In the few boxes of Black Hills remanufactured ammo I've had they were loaded in the same cases (Lake City I think)by maker but mixed year. Thre's nothing wrong with loading different headstamps but mixing them in the same group can open up the group.

Looking at your group it looks almost like you have a high group and a low group that could be ammo, breathing/position, or drifting aim point (focus). To be honest I'm just getting into scoped rifles. I've shot Service Rifle since 98, some of it crosses over but bags and bipods are a little less familiar. (I still shoot prone with a sling to test ammo as I get better groups.)

Well I finished what I had to sort and almost a 1K or LC

Your observation is true there are two 5 shot groups. I think the wind and my POI changed some from string to string

 

[insight3b]

This helped me:
AR-15 Carrier Weight System - AR 15 PRODUCTS by Superior Shooting Systems

 

[sinister]

Your post leaves way too much open to guessing.

While brass sorting helps it's not the end-all for precision loads (especially at short ranges of only 100 and 200 yards in an autoloader).

What dies are you using for sizing and bullet seating? How are you throwing your powder charges? Why are you sacrificing precision for velocity? Why are you trying to clone a military load (using cannister grade powder) with an alternate consumer propellant?

A suppressed military special operations SPR is not designed to shoot benchrest bugholes. Besides the fact you're shooting a Noveske upper we don't know anything about your scope, trigger, barrel state, shooting style, and how you're resting your rifle. You've added a suppressor which may also vary your vertical harmonics depending on how much it weighs.

The old (1999-2002) Navy competition load was VERY accurate and used somewhere around 23.5 to 24 grains of TAC -- but cases out of 20-inch M16s were pretty sooty.

As noted, horizontal spread is caused by wind. Vertical spread is either the shooter or velocity variances.

 

[sandwarrior]

I'm not sure where you got TAC as the powder of choice for Mk262? And especially that much, 24 gr.? My old sources said 25.5 gr. of RE-15. When I loaded for my carbine it produced 2690 fps and about 1.25 moa very consistently. That (accuracy) was more my rifle than the load. But, that lower pressure/longer burning load produced consistent velocities. I use close that same load as an accuracy, high velocity load from a bolt gun, but knock it down to 25 gr. That's because the bolt gun is a straight .223 and won't handle 5.56 pressures.

I do this across a very wide range of headstamps. For shooting super tight groups with the bolt gun I go to AA2015 (23.8 gr.). I don't get the velocity I do with RE-15 so pushing the same bullet out at long distances means equal winds affect it more.

Some food for thought.

 

[leid]

Howdy OP,
I did post groups on this board after cloning the BH MK 262 MOD 1 cartridge a couple years back using 77gr SMK w/o cannelure over canister-grade TAC in LC casings with CCI 5.56MM primers. As stated above, the actual Black Hills cartridge uses either LC or WCC 5.56MM brass loaded with a 77gr. SMK with cannelure over spherical powder verified by disassembly of the factory cartridge. I used virgin LC casings. According to an email from Western Powders Ballistics Lab/Ramshot, the actual powder used in BH MK 262 MOD 1 ammunition is a non-canister form of their spherical powder. According to information from Black Hills, BH had the powder used in current MK 262 MOD 1 stabilized to very-high-temperatures to alleviate overpressure when the COLT M4/M4A1 carbine is forced to serve in what amounts to a SAW role (see link to CRANE data below). IMO, the closest canister-grade powder you can find is TAC but I did work up H335, RL-15, AA2520, Varget, N540, H4895, & a few others. All worked more or less but TAC got the final nod after taking both velocity & accuracy into account. It was win-win on both. 5.56MM NATO pressure loading data for TAC became available several years back so use the latest/most credible published data you can find. I used CCI 5.56MM primers to deal with high pressure & the NON-cannelured 77gr. SMK bullet because I don't crimp my 77gr. SMK loadings. Above were assembled to 2.245" COAL same as BH MK 262 MOD 1 in a Wilson arbor die to keep run-out to a minimum. Velocity of the actual MK 262 MOD 1 cartridge in the 18" Krieger/CLE 1x7.7 twist barrel I used was 2825 FPS vs 2824 FPS for the clone with virtually the same accuracy of 0.5-0.6" @100yds. & easily sub-MOA out to 750yds. in good conditions. No sweat, the MK 262 MOD 1 cartridge can be cloned using TAC but it does carry limitations. Things to remember about TAC: TAC starts to deliver longer-range accuracy at high pressure levels because measured SD comes way down as you approach full 5.56MM NATO pressure. Expect a MK 262 MOD 1 clone loading to be VERY hard on brass. I only load brass twice at full 5.56MM NATO pressure. Lot-to-lot variation of TAC requires work-up when changing lots. You can not assume anything when working at close to full 5.56MM NATO pressure. Last but not least & this is VERY important: Pressure on the clone cartridge is at the top of acceptable 5.56MM NATO levels while the factory BH cartridge develops much lower pressure due to the non-canister powder used in the factory loading. BH MK 262 MOD 1 is limited to 5.56MM mil-spec pressure of 58,700 PSI while the clone will be developing very close to full 5.56MM NATO pressure of approximately 62,350 PSI. Given this last fact, the clone is of more limited value than the actual factory cartridge when it comes to high OAT/barrel temperatures. IMO, the safety factor designed into the factory Black Hills MK 262 MOD 1 cartridge can not be replicated in the clone cartridge with available canister grade powders. So even with a clone cartridge in hand, I still use factory BH MK 262 MOD 1 ammunition when a fully weaponized 5.56MM combat cartridge is desirable. Err on the side of caution when developing this clone loading so as not to become a member of the "I blew up my AR-15/M16" club. I speak from experience as I became a member of the fore mentioned club in the '70s while working up an accurate 70gr. loading. Retrospect tells me the load was fine until the weapon got hot. The bolt failed catastrophically just after practicing a single 30 round mag of 2-5 round burst-fire. Reason: the powder used was not stabilized to very high temperature so pressure went off the chart in my hot weapon prior to cook-off. NAVY CRANE data on this subject is a great read: http://www.dtic.mil/ndia/2006smallarms/marsh.pdf HTH & good luck!

EDIT: I could not find my old post so here is a target from 750yds. firing a 77gr. SMK over TAC handload from an 18" SS Kreiger/CLE 1x7.7 upper w M4 suppressor off the tool box of my 4WD

Factory BH MK 262 MOD 1 from same barrel @ 500yds. (4.14") & 100yds. (0.61")

 

[sandwarrior]

Leid,

Thanks for the post. I can't find the source I used to find RE-15 as the powder, but I do know that is what I was told. So, I worked it up and got what I had hoped for in my 16" carbine. I got what I hoped for in velocity and while firing fast, not getting too much case damage. The principle with it is a little more of a slower powder will give a longer push but less initial pressure. Less pressure usually relates to less heat.

However, thinking this through, what would you think about the RE-15 if cases sat in a hot chamber for a little while. Even though I was not getting hot signs on cases fired in rapid succession, I never really did a hard test cooking rounds off. I have seen a number of M193 and M80 rounds cook off from M-16A1/Car 15 and M60 MG's. So, I know there has to be some stopping point at which the testers accept rounds heated in a hot barrel.

 

[gunsnjeeps]

I get 2750 fps for M262. 24.5 grains of Varget gives me the same velocity. I have no accuracy change with 24 grains of Varget at 2700 fps. I have a minute of elevation difference at 600 yards between 2700 and 2750. I use the 24 grain load.

 

[BC 6.8]

My experience with Reloader 15 is leaving a round in a hot chamber for any length of time will cause increased velocity and probably increased pressure. Re15 is not very temp stable, so I would recommend caution when loading near max levels.

 

[sandwarrior]

My experience with Reloader 15 is leaving a round in a hot chamber for any length of time will cause increased velocity and probably increased pressure. Re15 is not very temp stable, so I would recommend caution when loading near max levels.

That is kind of what I'd thought. The good thing is, you can't hardly compress enough RE-15 in a .223/5.56 case to get a max pressure load with a 75/77 gr. bullet.

 

[1slow01z71]

Great thread, I've got a k of the 77gr CCs I was planning on trying here soon as well. Glad to know I don't have to sort my LC brass by year. I think I'll try my hand with varget though as I've got about 20 pounds of that. I'm new to reloading so am I missing something with the allure of using TAC when from what I've read many people have had better luck with varget when trying to push the heavier pills. I also was unaware you could get stouter primers for the real hot rod loads.

 

[sandwarrior]

Great thread, I've got a k of the 77gr CCs I was planning on trying here soon as well. Glad to know I don't have to sort my LC brass by year. I think I'll try my hand with varget though as I've got about 20 pounds of that. I'm new to reloading so am I missing something with the allure of using TAC when from what I've read many people have had better luck with varget when trying to push the heavier pills. I also was unaware you could get stouter primers for the real hot rod loads.

IMO, Varget is the better choice for a heavy bullet in .224" cal.

 

[BoilerUP]

8208xbr...

 

[sandwarrior]

8208xbr...

Good choice as well I understand. I have yet to work with it in the .223/5.56. I started buying and using it in a 6.5 Grendel. ADDED: where it became my "Go-To" load.

 

[Rprecision]

I'm not sure where you got TAC as the powder of choice for Mk262? And especially that much, 24 gr.? My old sources said 25.5 gr. of RE-15. When I loaded for my carbine it produced 2690 fps and about 1.25 moa very consistently. That (accuracy) was more my rifle than the load. But, that lower pressure/longer burning load produced consistent velocities. I use close that same load as an accuracy, high velocity load from a bolt gun, but knock it down to 25 gr. That's because the bolt gun is a straight .223 and won't handle 5.56 pressures.

I do this across a very wide range of headstamps. For shooting super tight groups with the bolt gun I go to AA2015 (23.8 gr.). I don't get the velocity I do with RE-15 so pushing the same bullet out at long distances means equal winds affect it more.

Some food for thought.

I never said it was, but it seemed to be a good place to start based on others work. And, like I said its the only thing I could get.

Ramshot lists

TAC 77 SIE HPBT 22.3 2,648 24.8 2,902 61,500 2.260

So my load isnt "that much" like you think. And before you go running to the safety police, I worked up to it.

Howdy OP,
I did post groups on this board after cloning the BH MK 262 MOD 1 cartridge a couple years back using 77gr SMK w/o cannelure over canister-grade TAC in LC casings with CCI 5.56MM primers. As stated above, the actual Black Hills cartridge uses either LC or WCC 5.56MM brass loaded with a 77gr. SMK with cannelure over spherical powder verified by disassembly of the factory cartridge. I used virgin LC casings. According to an email from Western Powders Ballistics Lab/Ramshot, the actual powder used in BH MK 262 MOD 1 ammunition is a non-canister form of their spherical powder. According to information from Black Hills, BH had the powder used in current MK 262 MOD 1 stabilized to very-high-temperatures to alleviate overpressure when the COLT M4/M4A1 carbine is forced to serve in what amounts to a SAW role (see link to CRANE data below). IMO, the closest canister-grade powder you can find is TAC but I did work up H335, RL-15, AA2520, Varget, N540, H4895, & a few others. All worked more or less but TAC got the final nod after taking both velocity & accuracy into account. It was win-win on both. 5.56MM NATO pressure loading data for TAC became available several years back so use the latest/most credible published data you can find. I used CCI 5.56MM primers to deal with high pressure & the NON-cannelured 77gr. SMK bullet because I don't crimp my 77gr. SMK loadings. Above were assembled to 2.245" COAL same as BH MK 262 MOD 1 in a Wilson arbor die to keep run-out to a minimum. Velocity of the actual MK 262 MOD 1 cartridge in the 18" Krieger/CLE 1x7.7 twist barrel I used was 2825 FPS vs 2824 FPS for the clone with virtually the same accuracy of 0.5-0.6" @100yds. & easily sub-MOA out to 750yds. in good conditions. No sweat, the MK 262 MOD 1 cartridge can be cloned using TAC but it does carry limitations. Things to remember about TAC: TAC starts to deliver longer-range accuracy at high pressure levels because measured SD comes way down as you approach full 5.56MM NATO pressure. Expect a MK 262 MOD 1 clone loading to be VERY hard on brass. I only load brass twice at full 5.56MM NATO pressure. Lot-to-lot variation of TAC requires work-up when changing lots. You can not assume anything when working at close to full 5.56MM NATO pressure. Last but not least & this is VERY important: Pressure on the clone cartridge is at the top of acceptable 5.56MM NATO levels while the factory BH cartridge develops much lower pressure due to the non-canister powder used in the factory loading. BH MK 262 MOD 1 is limited to 5.56MM mil-spec pressure of 58,700 PSI while the clone will be developing very close to full 5.56MM NATO pressure of approximately 62,350 PSI. Given this last fact, the clone is of more limited value than the actual factory cartridge when it comes to high OAT/barrel temperatures. IMO, the safety factor designed into the factory Black Hills MK 262 MOD 1 cartridge can not be replicated in the clone cartridge with available canister grade powders. So even with a clone cartridge in hand, I still use factory BH MK 262 MOD 1 ammunition when a fully weaponized 5.56MM combat cartridge is desirable. Err on the side of caution when developing this clone loading so as not to become a member of the "I blew up my AR-15/M16" club. I speak from experience as I became a member of the fore mentioned club in the '70s while working up an accurate 70gr. loading. Retrospect tells me the load was fine until the weapon got hot. The bolt failed catastrophically just after practicing a single 30 round mag of 2-5 round burst-fire. Reason: the powder used was not stabilized to very high temperature so pressure went off the chart in my hot weapon prior to cook-off. NAVY CRANE data on this subject is a great read: http://www.dtic.mil/ndia/2006smallarms/marsh.pdf HTH & good luck!

EDIT: I could not find my old post so here is a target from 750yds. firing a 77gr. SMK over TAC handload from an 18" SS Kreiger/CLE 1x7.7 upper w M4 suppressor off the tool box of my 4WD

Factory BH MK 262 MOD 1 from same barrel @ 500yds. (4.14") & 100yds. (0.61")

Leid, Thank you for the information. I will keep working at it, I wish I had more choices for powders available I would go wild on it. Varget would be on the top to try.

I read the attached article by crane, I think anyone who has worked around these weapons systems has a gut feeling that temps get much higher then we thought.

 

[leid]

Rprecision,
Just so I don't loose anyone on this, here are some basics on smokeless powder types. Smokeless powders are roughly divided into two groups: single based & double based. Single based powders (most of the stick rifle powders such as Varget/H4895) are made from nitrocellulose and can be made to be extremely temp stable as compared to double based powders. But you leave a little energy (MV) on the table when you go with a single based powder. Double based powders (virtually all the spherical powders including TAC) are made from a mix of nitrocellulose & nitroglycerin. The nitroglycerin gives added energy (MV) potential but at a cost. Generally, double based powders are not as temperature stable as single based powders. No real surprise that nitroglycerin is a bit unstable, right? Now comes the caveat: both types of powder vary in the individual thermal stability & available energy (MV). Some of the best double based powders are just about as temp stable as the worst single based powders. And some of the best single based powders have just about as much energy (MV) as the worst double based powders. As handloaders, we look for smokeless powder propellants that offer the balance of accuracy/velocity/thermal stability that best suits our intended purposes.

Now that everyone is a little better prepared to understand the "WHY" concerning large differences in MV/thermal stability, here are my actual measured values. Hodgdon also has published their values on thermal stability for a much larger group of powders but none of their testing was on the 5.56MM cartridge: http://hodgdon.com/smokeless/extreme/page2.php#top. I was not sure that thermal stability was anywhere near constant over different cartridges/calibers. Our results on Varget & H4895 were similar which leads me to believe my test results for TAC & the (2) factory cartridges are at least in the ball park. I just could not come close to matching the measure velocity of factory MK 262 Mod 1 (2825FPS) in this 18" barrel using the 77gr SMK over 5.56MM NATO pressure VARGET (2685FPS) or H4895 (2741FPS) but both these single based powders easily grouped sub MOA. And both have the added advantage of being extremely temperature stable, apparently much more so than double based TAC or the non-canister double based powder in factory BH MK 262 MOD 1. Southwest Ammunition made an excellent 5.56MM 77gr. SMK loading using a Hodgdon's Extreme single based stick rifle powder but it was a little slower than BH MK 262 MOD 1 in my barrel making 2746FPS. Black Hills went for the added velocity available with double based powder for their MK 262 MOD 1 LR AA53 combat loading but they did forfeit the relative thermal stability of the SWA 77gr SMK loading using single based powder. As per emails from Western Powders Ballistics Lab/Ramshot, the canister grade double based TAC you buy exceeds U.S. mil spec on thermal stability. But TAC is just not nearly as thermally stable as single based powders such as H4895 or Varget. So be careful using canister grade TAC at full 5.56MM NATO pressure levels. I heated a TAC clone cartridge to 135F just to measure the difference in MV & it was significant (2824FPS@70F vs 2875FPS@135F). Best to use factory BH MK 262 MOD 1 or some other mil-spec cartridge for CQ drills/automatic fire. What does H4895 do at 135F? Virtually the same as it does at -10F (2737FPS@-10F vs 2741FPS@135F). That is a whopping 4FPS average difference in MV (-10F to +135F over 5 rounds). And although single based Varget did not make impressive MV numbers, it varied by an average of 1FPS (-10F to +135F over 5 rounds). All cartridges referenced above were full 5.56MM NATO pressure 77gr. SMK loadings. IMO, TAC shines at near full 5.56MM NATO pressure on 69gr bullets loaded to mag-length up to over-mag-length 80gr VLD. It may or may not be the best powder in your barrel or with bullets under 69gr.

Commercial grade factory BH MK 262 MOD 1 is finally becoming available again & so are clone reloading components. Find out what factory BH MK 262 MOD 1 will do in your barrel in terms of both accuracy & actual measured MV. Without a chrono, it is just an educated guess. You need firm measurements preferable over at least 5 rounds. BH makes over ten 77gr. SMK loadings so be sure you have one of the real-deal MK 262 MOD 1 cartridge. It comes in several forms: full mil-spec AA53, commercial grade, & commercial grade SECONDS. For our purposes, it does not matter which form. The Black Hills 5.56MM 77gr. SMK AMU MATCH load (ARMY/NAVY/USMC all have their own 77gr. SMK MATCH version) is loaded a bit slower than MK 262 MOD 1 & has proven capable of 0.5 MOA@500yds. accuracy in good conditions. It also uses a double based spherical powder verified by disassembly. HTH & good luck!

Here are results of my "backyard" relative thermal stability test all fired in 18" SS 1x7.7 Krieger/CLE 5.56MM chambered barrel in graph form:

 

[sandwarrior]

Rprecision,

Someone above (previously) found a source that gave TAC as a powder that was used in Mk262 ammunition. I just hadn't seen it before. Many years ago, I was searching for the "the" powder they used and was told RE-15. That's my only source. And it worked out, so I never questioned it further. When I worked with TAC, I was getting pressure signs before I got desired velocity. Thinking back that may have been because I was working it up in my bolt gun or an earlier AR which had .223 chambers instead of a 5.56.

FWIW, we don't call 911 to get the safety police here. Their only job is to affix blame.

 

[BCP]

Great thread, I've got a k of the 77gr CCs I was planning on trying here soon as well. Glad to know I don't have to sort my LC brass by year. I think I'll try my hand with varget though as I've got about 20 pounds of that. I'm new to reloading so am I missing something with the allure of using TAC when from what I've read many people have had better luck with varget when trying to push the heavier pills. I also was unaware you could get stouter primers for the real hot rod loads.

Tac gives velocity varget will give you accuracy.

My 'mk262' clone load was 77nosler or 75hornady, 24.1 TAC, cci primer in LC brass. I seated them 2.245"

Varget load I used same components and COAL but 24.3 varget and it shot a lot better but 50fps slower.

 

[gunsnjeeps]

I always heard TAC was the closest powder to M262 when we started geting it issued as match ammo. I started loading with Varget and got the same velocity and accuracy. I have a pound of TAC but have never opened it. TAC lists 5.56 pressure loads 22.3 grains at 2648 to 24.8 for 2902 FPS. If I were to guess I'd put M262 just under 23 grains.

 

[Rprecision]

Rprecision,

Someone above (previously) found a source that gave TAC as a powder that was used in Mk262 ammunition. I just hadn't seen it before. Many years ago, I was searching for the "the" powder they used and was told RE-15. That's my only source. And it worked out, so I never questioned it further. When I worked with TAC, I was getting pressure signs before I got desired velocity. Thinking back that may have been because I was working it up in my bolt gun or an earlier AR which had .223 chambers instead of a 5.56.

FWIW, we don't call 911 to get the safety police here. Their only job is to affix blame.

To be honest I probably took your post out of context and was being a dick. Besides how it appears, I do appreciate the information Thanks

Tac gives velocity varget will give you accuracy.

My 'mk262' clone load was 77nosler or 75hornady, 24.1 TAC, cci primer in LC brass. I seated them 2.245"

Varget load I used same components and COAL but 24.3 varget and it shot a lot better but 50fps slower.

I noticed all my load info suggests a COAL of 2.260. I noticed you load at 2.245" any specific reason ?

 

[Rprecision]

Rprecision,
Just so I don't loose anyone on this, here are some basics on smokeless powder types. Smokeless powders are roughly divided into two groups: single based & double based. Single based powders (most of the stick rifle powders such as Varget/H4895/RL-15) are made from nitrocellulose and can be made to be extremely temp stable as compared to double based powders. But you leave a little energy (MV) on the table when you go with a single based powder. Double based powders (virtually all the spherical powders including TAC) are made from a mix of nitrocellulose & nitroglycerin. The nitroglycerin gives added energy (MV) potential but at a cost. Generally, double based powders are not as temperature stable as single based powders. No real surprise that nitroglycerin is a bit unstable, right? Now comes the caveat: both types of powder vary in the individual thermal stability & available energy (MV). Some of the best double based powders are just about as temp stable as the worst single based powders. And some of the best single based powders have just about as much energy (MV) as the worst double based powders. As handloaders, we look for smokeless powder propellants that offer the balance of accuracy/velocity/thermal stability that best suits our intended purposes.

Now that everyone is a little better prepared to understand the "WHY" concerning large differences in MV/thermal stability, here are my actual measured values. Hodgdon also has published their values on thermal stability for a much larger group of powders but none of their testing was on the 5.56MM cartridge: http://hodgdon.com/smokeless/extreme/page2.php#top. I was not sure that thermal stability was anywhere near constant over different cartridges/calibers. Our results on Varget & H4895 were similar which leads me to believe my test results for TAC & the (2) factory cartridges are at least in the ball park. I just could not come close to matching the measure velocity of factory MK 262 Mod 1 (2825FPS) in this 18" barrel using the 77gr SMK over 5.56MM NATO pressure VARGET (2685FPS) or H4895 (2741FPS) but both these single based powders easily grouped sub MOA. And both have the added advantage of being extremely temperature stable, apparently much more so than double based TAC or the non-canister double based powder in factory BH MK 262 MOD 1. Southwest Ammunition made an excellent 5.56MM 77gr. SMK loading using a Hodgdon's Extreme single based stick rifle powder but it was a little slower than BH MK 262 MOD 1 in my barrel making 2746FPS. Black Hills went for the added velocity available with double based powder for their MK 262 MOD 1 LR AA53 combat loading but they did forfeit the relative thermal stability of the SWA 77gr SMK loading using single based powder. As per emails from Western Powders Ballistics Lab/Ramshot, the canister grade double based TAC you buy exceeds U.S. mil spec on thermal stability. But TAC is just not nearly as thermally stable as single based powders such as H4895 or Varget. So be careful using canister grade TAC at full 5.56MM NATO pressure levels. I heated a TAC clone cartridge to 135F just to measure the difference in MV & it was significant (2824FPS@70F vs 2875FPS@135F). Best to use factory BH MK 262 MOD 1 or some other mil-spec cartridge for CQ drills/automatic fire. What does H4895 do at 135F? Virtually the same as it does at -10F (2737FPS@-10F vs 2741FPS@135F). That is a whopping 4FPS average difference in MV (-10F to +135F over 5 rounds). And although single based Varget did not make impressive MV numbers, it varied by an average of 1FPS (-10F to +135F over 5 rounds). All cartridges referenced above were full 5.56MM NATO pressure 77gr. SMK loadings. IMO, TAC shines at near full 5.56MM NATO pressure on 69gr bullets loaded to mag-length up to over-mag-length 80gr VLD. It may or may not be the best powder in your barrel or with bullets under 69gr.

Commercial grade factory BH MK 262 MOD 1 is finally becoming available again & so are clone reloading components. Find out what factory BH MK 262 MOD 1 will do in your barrel in terms of both accuracy & actual measured MV. Without a chrono, it is just an educated guess. You need firm measurements preferable over at least 5 rounds. BH makes over ten 77gr. SMK loadings so be sure you have one of the real-deal MK 262 MOD 1 cartridge. It comes in several forms: full mil-spec AA53, commercial grade, & commercial grade SECONDS. For our purposes, it does not matter which form. The Black Hills 5.56MM 77gr. SMK AMU MATCH load (ARMY/NAVY/USMC all have their own 77gr. SMK MATCH version) is loaded a bit slower than MK 262 MOD 1 & has proven capable of 0.5 MOA@500yds. accuracy in good conditions. It also uses a double based spherical powder verified by disassembly. HTH & good luck!

Here are results of my "backyard" relative thermal stability test all fired in 18" SS 1x7.7 Krieger/CLE 5.56MM chambered barrel in graph form:

Thank you so much for all the information!

I will try to get my hands on a box of the real stuff

As far as my stuff now, I have all the brass sorted and plan to go back to the basics and devolop a load and see what I can do with what I got. Hopefully in the mean time some powder will show up and offer some options if that doesent pan out.

The goal was not to go whip up 1k of ammo that didnt work well and be stuck with expensive plinking ammo.

I really apprecate everyones help, thank you !

 

[leid]

Rprecision,
I have had a lot of guys show me what they thought was BH MK 262 MOD 1. The cartridges they had were actually one of the many BH 77gr. SMK loads such as the 5.56MM AMU load or commercial grade .223 pressure 77gr. SMK load. These cartridges are not loaded to the same MV as the MK 262 MOD 1 AA53 combat loading. Some guys did come up with genuine BH MK 262 MOD 0 (circa 2002) which is basically the BH MK 262 loading with a non-cannelure 77gr. SMK bullet. MOD 0 will work just fine unless you fire it in an overheated weapon. The bullet in genuine BH MK 262 MOD 1 will have a cannelure & the spherical powder in current BH MK 262 MOD 1 was further thermally stabilized around 2005. The 20 round boxes of mil-spec BH MK 262 MOD 1 AA53 are easily recognized since the face of the box is marked. And this is the current packaging for commercial grade BH MK 262 MOD 1: Black Hills Ammo 5.56x45mm NATO 77 Grain Sierra MatchKing Hollow Point.

 

[Xcount]

Leid,
I believe RE-15 is double based, probably why it shows the temp sensitivity.

The first year I shot PACFLT matches was '99 and we were issued HSM ammo in the bright orange boxes. It had 69 grainers and most people with AR's got kicked around quite a bit compared to the M1A shooters. The next year they issued BH contracted ammo with 75 gr Hornady's, it was much better but nothing compared to the MK262 that was issued in '01. I took a EIC medal in '11 and was issued MK262Mod1 that has chronied 2900 in four different service rifles and two different chrony's. That stuff is almost as good as it gets.
I believe the best stuff going now is the Atlanta Arms ammo developed for AMU/NG teams. It's 26grains of a new generation powder from St. Marks, FL. it's faster than MK262 and just as accurate. good luck trying to clone it.
I don't get why people try and clone military developed powder using commercial powders. If that was the case why wouldn't the Navy just stuff Varget into a case? They develop powders ($$$$$) because nothing is available off the shelf that does the job and you will have problems with accuracy or overpressure parts breakage or cooking off. an extra 100fps really isn't worth it, it's almost nothing on the target.

 

[leid]

Xcount,
I just looked it up to be sure & you are absolutely correct. Reloader 15 is one of the double based rifle powders. Thanks for the correction. I read about the newest MATCH & proposed combat loading using St. Marks powders on their site. Improvements in propellants are always welcome. Maybe an OPTIMIZED MK 262 MOD 1 will be marketed.

 

[sandwarrior]

Leid,
I believe RE-15 is double based, probably why it shows the temp sensitivity.

The first year I shot PACFLT matches was '99 and we were issued HSM ammo in the bright orange boxes. It had 69 grainers and most people with AR's got kicked around quite a bit compared to the M1A shooters. The next year they issued BH contracted ammo with 75 gr Hornady's, it was much better but nothing compared to the MK262 that was issued in '01. I took a EIC medal in '11 and was issued MK262Mod1 that has chronied 2900 in four different service rifles and two different chrony's. That stuff is almost as good as it gets.
I believe the best stuff going now is the Atlanta Arms ammo developed for AMU/NG teams. It's 26grains of a new generation powder from St. Marks, FL. it's faster than MK262 and just as accurate. good luck trying to clone it.
I don't get why people try and clone military developed powder using commercial powders. If that was the case why wouldn't the Navy just stuff Varget into a case? They develop powders ($$$$$) because nothing is available off the shelf that does the job.

When you say service rifle, you mean 20" barrel and rifle gas path length? That would seem a lot closer to what I was able to get in my long barreled .223 bolt gun.

 

[Xcount]

yes, basically the outward appearance of an A2 configuration.

 

[BC 6.8]

Leid,
I believe RE-15 is double based, probably why it shows the temp sensitivity.

The first year I shot PACFLT matches was '99 and we were issued HSM ammo in the bright orange boxes. It had 69 grainers and most people with AR's got kicked around quite a bit compared to the M1A shooters. The next year they issued BH contracted ammo with 75 gr Hornady's, it was much better but nothing compared to the MK262 that was issued in '01. I took a EIC medal in '11 and was issued MK262Mod1 that has chronied 2900 in four different service rifles and two different chrony's. That stuff is almost as good as it gets.
I believe the best stuff going now is the Atlanta Arms ammo developed for AMU/NG teams. It's 26grains of a new generation powder from St. Marks, FL. it's faster than MK262 and just as accurate. good luck trying to clone it.
I don't get why people try and clone military developed powder using commercial powders. If that was the case why wouldn't the Navy just stuff Varget into a case? They develop powders ($$$$$) because nothing is available off the shelf that does the job and you will have problems with accuracy or overpressure parts breakage or cooking off. an extra 100fps really isn't worth it, it's almost nothing on the target.

That is insane velocity from a 20" barrel. Most of the loads I use or see being used run about 2760 fps out of a 20".

 

[BCP]

To be honest I probably took your post out of context and was being a dick. Besides how it appears, I do appreciate the information Thanks



I noticed all my load info suggests a COAL of 2.260. I noticed you load at 2.245" any specific reason ?

Black hills I had shot great and was the same COAL. MK262 was also short like 2.24"

 

[Xcount]

That is insane velocity from a 20" barrel. Most of the loads I use or see being used run about 2760 fps out of a 20".

that's what I thought and that's why I tested it in two of my uppers and a NG team shooter I know got the same results in different testing. He's the one that told me about the AA ammo being 26 grains of a ball powder from St. Marks and it's even faster that MK262.

I thought this was all old news?? that AA ammo has been out for about two years.

 

[sinister]

US-made General Dynamics - St. Marks powder pushes a 77 Sierra Match King 100 feet per second faster than legacy Mark 262 to match the flight path of M855 GI Ball. It technically simplifies things if everyone is issued a standard ACOG.

 

[Xcount]

I concur with the 100fps increase, at least that is what my buddy told me it did in his rifle. as good as that stuff is though a 80gr Amax at a leisurely 2750 shoots inside it by almost half a minute. I ran short of ammo at a match once and someone gave me a box of AA to help me out, it shot almost the same elevation as my Amax load so it's really moving. but you did have to watch the wind better. I shot one point less than my last string. It's good stuff for mag length.

 

[sandwarrior]

Sinister,

Something isn't right with their chart. 77 gr. OTM isn't going to start dropping faster than M855 as distance progresses. The green line on the chart should have the separation at the other end of it. And, it probably needs to start above M855. You should also see the blue line making a separation from the M855 as it has the same better BC than does the 62 gr. bullet.

 

[sinister]

I don't think there's any general or SOF-issued military 77-grain ammo out using St. Marks (ball) powder -- but they are selling powder that both Alliant and Hodgdon have re-branded. Take a look at 2000MR and AR-Comp numbers.

Atlanta Arms and the USAMU's internal hand loads both shoot hotter and flatter than Mark 262.

 

[vvillium3]

8208xbr...

x2! Always on my shelves locally, hope it doesn't catch on. Out of my 18" WOA with 23.8 gr 8208xbr & 77 gr SMK I get a constant 2730 fps. Its a lights out load and consistently under 1moa anywhere between 50 & 600 yards. Haven't really stretched them out further, as I haven't had the time. Plus these little .223's are super sensitive to the wind, want to try out the lapua 77gr and see if they buck the wind any better.

 

[Rprecision]

updated OCW

First thing I separated my remaining 24.0 loads by head stamp and shot it over again.



WCC on top LC on the bottom. Nothing to write home about for 200 yards



So I went back to the drawing board and started over with OCW. I shot everything round robin spreading out the variables. I loaded WCC cases to 2.260" with 23.5, 23.7, 23.9, 24.1, 24.3, 24.5, 24.7

Here's the results:





I am not a expert at using OCW as this is only my second time using this load development strategy. I did take a few things away from the test. Loading at 24.0 (original load) is close to 24.3 scatter node. This tends to make sense as this load shot best during cold weather and thus slightly lower pressure. Anything over 24.1 is worthless. 23.8 ish may be a good place to do so more work. I am also considering working 23.0-23.5 to see what else is there.

My plan is to find the most accurate charge weight then vary the seating depth deeper by .010" at a time to see if more can be had.

So there's a update, Any thoughts or recommendations?

 

[BC 6.8]

I would try to stay around 23.8-23.9 gr and then practice shooting. Practicing will get you better results then continuing to tweak the load.

 

[leid]

RPrecision,
I had the guys laughing when I mounted a 24BR scope on an entry gun in place of the Eotech: they repeatedly made reference to a monkey riding a football. No choice as my MK4 eyeballs are 60. Anyway, here is a group fired with a 10.5" 1x7 twist SS Noveske barrel with M4 can @100yds. with the non-cannelured 77gr. SMK bullet over 24.8gr. TAC (the MAX 5.56MM NATO charge listed by Ramshot) in virgin LC case seated to COAL 2.255"@100yds.: 0.68". I think it is about the same profile/same chamber as your barrel just shorter. So I would think your 18" Noveske barrel should be capable of a good bit more accuracy. Make sure nothing is loose on your rig then shoot a few groups without the can/mount to make sure something is not amiss there. I have found suppressor mounts & forends that pooched my groups no matter what I tried with them. One forend shot well only if I rest the rifle on a bag just past the mag well: bad vibes apparently in the forend when resting way out front or on a bipod. As far as charge weight of TAC, I would fully expect the 77gr. SMK over 24.0-24.3gr to shoot right at or sub 0.5 MOA off a bench@100yds. in an accurized rifle during trigger pull conditions. Also, 77gr. bullets are not alike so perhaps your barrel would prefer the SMK.
Gotta' start working on a 180gr. TTSX over RL22 (or H4350 if the LGS has any) 30-06 elk load. HTH

 

[BCP]

I've shot a bunch of WCC brass cased loads and never got the kind of accuracy out of that brass that I do from LC or RP. Also try a shorter COAL my groups with my bravocompany barrel didn't get really tight or consistent until I seated deep.

Right now with WCC brass I am using 26gr 2000MR and a 69smk and I'll get groups of around an inch, usually 2-3 int he same hole and then fliers opening it to around 1-1.25". Now, if I use LC or RP brass and the same charge, the fliers dissappear. I have checked for run out etc and that isn't it so I think the cases are more inconsistent.

 

[Rprecision]

I would try to stay around 23.8-23.9 gr and then practice shooting. Practicing will get you better results then continuing to tweak the load.

fair advice

RPrecision,
I had the guys laughing when I mounted a 24BR scope on an entry gun in place of the Eotech: they repeatedly made reference to a monkey riding a football. No choice as my MK4 eyeballs are 60. Anyway, here is a group fired with a 10.5" 1x7 twist SS Noveske barrel with M4 can @100yds. with the non-cannelured 77gr. SMK bullet over 24.8gr. TAC (the MAX 5.56MM NATO charge listed by Ramshot) in virgin LC case seated to COAL 2.255"@100yds.: 0.68". I think it is about the same profile/same chamber as your barrel just shorter. So I would think your 18" Noveske barrel should be capable of a good bit more accuracy. Make sure nothing is loose on your rig then shoot a few groups without the can/mount to make sure something is not amiss there. I have found suppressor mounts & forends that pooched my groups no matter what I tried with them. One forend shot well only if I rest the rifle on a bag just past the mag well: bad vibes apparently in the forend when resting way out front or on a bipod. As far as charge weight of TAC, I would fully expect the 77gr. SMK over 24.0-24.3gr to shoot right at or sub 0.5 MOA off a bench@100yds. in an accurized rifle during trigger pull conditions. Also, 77gr. bullets are not alike so perhaps your barrel would prefer the SMK.
Gotta' start working on a 180gr. TTSX over RL22 (or H4350 if the LGS has any) 30-06 elk load. HTH

That's awesome. I have a 12.5 Crusader too, although I never put it to the accuracy test. Both run modified Troy TRX and Alpha rails to accommodate the switch block. I am running a threaded AWC can for the specific point to avoid mounts. Although, you have a point, I haven't tried it without a can.

I've shot a bunch of WCC brass cased loads and never got the kind of accuracy out of that brass that I do from LC or RP. Also try a shorter COAL my groups with my bravocompany barrel didn't get really tight or consistent until I seated deep.

Right now with WCC brass I am using 26gr 2000MR and a 69smk and I'll get groups of around an inch, usually 2-3 int he same hole and then fliers opening it to around 1-1.25". Now, if I use LC or RP brass and the same charge, the fliers dissappear. I have checked for run out etc and that isn't it so I think the cases are more inconsistent.

Yeah all of my loads have been loaded at the 2.260 COAL, I think getting some jump may be interesting in how they perform. At least so far it seems the WCC's were the most consistent but I still need to work the LC's some more.

 

[Rprecision]

Update,

Been working on other things but had a chance to test some loads. I had some 24.0 Tac loads left which I reseated to 2.260”, 2.245”, 2.230”, 2.215.

I shot them all round robin to give a idea what COAL has on this load/rifle.

All of my original loadings were at 2.260”

Interesting results: