+1 to the Varget. Plus, it is supposed to be very temperature insensitive. I wouldn't know though, it's ALWAYS hot in Houston. lol
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MK262 clone 77Grain 5.56 load problems / updated OCW tests
- Thread starter Rprecision
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+1 to the Varget. Plus, it is supposed to be very temperature insensitive. I wouldn't know though, it's ALWAYS hot in Houston. lol
Yeah, the CCI #41 are mil-spec. I've been using Fed 205M because I haven't had any slam fire problems; however, when I finish up this batch of 5000, I have 5000 of 205MAR (I think that's the designation) that are made specifically for AR's to prevent slam fires (they have a thicker cup.)
I keep fooling with seating depth, but someone on this site pointed out that an AR is the worlds most expensive bullet puller. Guess that's one reason mil-spec is crimped, as I tested a few rounds and found that they do move out a few thou due to the BCG slamming home.
Very good point, and something a lot of guys don't consider. Atmospheric temp is not the only thing to consider.
Yeah, I consider it, but it's not a factor for me. Since I am shooting F-TR and must shoot single shot for which I use a Bob Sled http://www.uniquetek.com/site/696296/product/T1354, I don't drop the BCG until I am ready to fire. I use a bolt release that allows me to use my trigger finger https://www.storesonline.com/site/696296/product/T1355 . This minimizes each rounds exposure to chamber temp.
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How are yall getting so much varget in these little cases? After 23.6gr I noticed my col was growing, I was loading in .2gr increments and the more I went up the more my col grew. I stopped ar 24.2. So what am I missing here? This is with grafs 77gr hpbt aka SMK seconds in mixed headstamp. I know the mixed headstamp isnt going to be best for accuracy this was more just an exercise in trying out my new rcbs competition dies and to see how loading the heavies went. I was measuring col off the ogive as the tips of these seconds are terribly inconsistent.
Also all my pmags of different iterations would onky take a 2.25 col, 2.26 was dragging and sometines fail to feed. Seems like I've got to be doing something wrong but my 50gr vmax loads worked just fine...
Also all my pmags of different iterations would onky take a 2.25 col, 2.26 was dragging and sometines fail to feed. Seems like I've got to be doing something wrong but my 50gr vmax loads worked just fine...
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With Varget compression and crimps are your friend as you get into the higher charge weights.
I never had an issue with COAL growth due to compression, even with 24.5gr Varget and a 75/77 in commercial or LC brass. Never crimped, either.
If you haven't done so, using a drop tube, tapping the charged case on the bench, and/or swirling it around help settle the powder and reduce compression.
If you haven't done so, using a drop tube, tapping the charged case on the bench, and/or swirling it around help settle the powder and reduce compression.
24 and 24.2 actually had a ring on the hullet where the die was pushing so hard. I did not use a drop tube but I cant see that helping much. I do only have .002 of neck tension so maybe theyre popping back out a little. I cranked the seating die down another .01 and got .008. Figured it was the bullet deforming since the higher charges had the ring from the die on them. This is my first dealings with really compressed loads. My 178gr 308 load is a little crunchy but not bad. Ive never crimped a load so I'll need to look into that. I also need to get a neck sizing die as some of my brass had inconsistent neck tension.
I'll try being a little more careful with my powder dropping method.
I'll try being a little more careful with my powder dropping method.
Added the drop tube to my powder funnel and all is well. 24.2 had a slight bit of crunch but nothing like before. My 20" WOA barrel gets here today so hopefully I can run these over the chrono Sunday morning. Its amazing what a little bit of fall can do for powder consolidation.
It may be because I am not loading to magazine length. My competitions (F/TR) are all shot single shot, so my OAL is way out at 2.336. Also, I use a 5" drop tube. I did have a problem with fitting my charge into a Lapua case, but I switched to LC11. I only use .002 of neck tension and do not crimp.
As for cranking the die down another .01. I have found that rounds do not generally respond to really small changes. If you seat a bullet and then try to push it in another .01, it usually does not move .01 for me. You might see what happens with a new seating at that setting.
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Lots of good info in this thread. I too am loading a MK262ish round for my MK12 mod1 clone, 77gr SMK, OAL 2250, Ramshot TAC, CCI 41's and have tried several different cases.
First I tried PMC cases because I had a ton of them, they aren't date stamped but I've probably got a decade or more mixed together. I noticed right away that many of them have off center flash holes. They tend to vary in weight a fair amount - 96gr +-2gr, I weight sorted them to within 1gr but did not check water capacity. I started with the heavy batch (97-98gr) and saw speeds of 2700fps with 24.6gr and 2730 with 24.8gr, SD's in the teens - both grouped in the 1moa range. Next I switched to a 1gr lighter batch of PMC cases (96-97gr) and I lost about 20fps but group size didn't change much.
I decided to switch to some brand new Winchester brass I had laying around to see where that would fall, it averaged a bit lighter (about 95.5gr). Velocity fell off again, 24.8grs of TAC only netted me about 2660fps but group size still averaged around 1moa.
At the beginning of each test day I fired 10 rounds of Black Hills 77gr red box as a control, these performed pretty consistently with speeds around 2720fps. They also showed the most pressure signs out of everything I shot, noticeable marks on the case heads. These are loaded in WCC10 cases which are heavier than anything I used, they seem to average above 98grs. I think for my next batch I may try loading some of these WCC cases and see how much TAC it takes to duplicate the factory speeds.
P.S. I forgot to mention that I tried shooting batches of weight matched cases vs. batches of random weight cases (all from the same brand new Winchester lot). The weight matched case batches were consistently better in terms of SD but usually by a very small amount. I couldn't discern any accuracy differences between the batches in 100yrd 5 shot groups.
First I tried PMC cases because I had a ton of them, they aren't date stamped but I've probably got a decade or more mixed together. I noticed right away that many of them have off center flash holes. They tend to vary in weight a fair amount - 96gr +-2gr, I weight sorted them to within 1gr but did not check water capacity. I started with the heavy batch (97-98gr) and saw speeds of 2700fps with 24.6gr and 2730 with 24.8gr, SD's in the teens - both grouped in the 1moa range. Next I switched to a 1gr lighter batch of PMC cases (96-97gr) and I lost about 20fps but group size didn't change much.
I decided to switch to some brand new Winchester brass I had laying around to see where that would fall, it averaged a bit lighter (about 95.5gr). Velocity fell off again, 24.8grs of TAC only netted me about 2660fps but group size still averaged around 1moa.
At the beginning of each test day I fired 10 rounds of Black Hills 77gr red box as a control, these performed pretty consistently with speeds around 2720fps. They also showed the most pressure signs out of everything I shot, noticeable marks on the case heads. These are loaded in WCC10 cases which are heavier than anything I used, they seem to average above 98grs. I think for my next batch I may try loading some of these WCC cases and see how much TAC it takes to duplicate the factory speeds.
P.S. I forgot to mention that I tried shooting batches of weight matched cases vs. batches of random weight cases (all from the same brand new Winchester lot). The weight matched case batches were consistently better in terms of SD but usually by a very small amount. I couldn't discern any accuracy differences between the batches in 100yrd 5 shot groups.
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I have concluded that (1) My rifle dislikes Nosler 77 CC bullets (2) My rifle dislikes Ramshot Tac.
I am working on other options but this project has been disappointing so far.
Accuracy just isn't there
I am working on other options but this project has been disappointing so far.
Accuracy just isn't there
I would try changing one of those factors at a time. Grab a box of Sierras and try them with the TAC.
The MK 262 round COAL is 2.245" with the 77 MK
Black Hills use a version close to TAC but not identical.
The new MK 262 brass come from WW (WCC) already primed to Black Hills for loading
I use 24.0 of TAC in my SCAR with LC brass and CCI 41 primers and crimp using Lee Factory Crimp Die.
When it's available I would like to try AR COMP and CFE223, but I am very pleased with the TAC load.
Black Hills use a version close to TAC but not identical.
The new MK 262 brass come from WW (WCC) already primed to Black Hills for loading
I use 24.0 of TAC in my SCAR with LC brass and CCI 41 primers and crimp using Lee Factory Crimp Die.
When it's available I would like to try AR COMP and CFE223, but I am very pleased with the TAC load.
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I really need to pick up some TAC. So far 23.8 grains of varget over 77gr SMKs has produced good groups but haven't run it across the chrono yet. No pressure signs at 23.8 either, hoping with weight sorting cases Ill get even better accuracy and some good speed out of my 20" WOA barrel.
It might be for reliable feeding. The SAMMI length is 2.26 which is only 0.015 longer (the thickness of four sheets of copier paper) Back when I was loading for magazine length, I occasionally had one fail to feed because it got cocked in the magazine and got stuck. If you are more concerned with it going bang on every trigger pull than with benchrest accuracy, it might be a good idea to load it short of maximum oal. Just a guess though.
I've run a lot of TAC behind Hornady 75gr BTHPs, 69gr SMKs, and 77gr SMKs, and results have been pretty good. I've never been able to get Varget level accuracy, but accuracy has been acceptable considering the ease of loading with TAC (and the cost).
I've never had good results with 77gr SMKs over 24gr of TAC, and have usually run 23.6-23.8 gr in PMC cases over Wolf SR223 primers. Rifle is a flat top AR, and barrel is a 20" Lothar Walther with 1/7 twist. Velocity has averaged right around 2680-2700 fps, with groups averaging right at MOA. I'm sure I could shave a little off of that by running better brass, or even sorting brass and bullets, but its still acceptable considering I'm loading on a Dillon 550B.
I've never had good results with 77gr SMKs over 24gr of TAC, and have usually run 23.6-23.8 gr in PMC cases over Wolf SR223 primers. Rifle is a flat top AR, and barrel is a 20" Lothar Walther with 1/7 twist. Velocity has averaged right around 2680-2700 fps, with groups averaging right at MOA. I'm sure I could shave a little off of that by running better brass, or even sorting brass and bullets, but its still acceptable considering I'm loading on a Dillon 550B.
Every setup is different, but I would think you are safe at 23.8gn of varget. I run my 77gn SMKs in front of 25.0gn of Varget, from LC11 brass and have no pressure signs. It is not just words to say every setup is different. Some things that could change the equation include: my LaRue has a polygonal barrel instead of lands and grooves, so that would likely cause a different amount of resistance to the pill. I coat my bullets with Boron Nitride, which would also cause the bullets to experience a different amount of resistance. We both have 20" barrels. I have a Wylde chambered action, so that could have a different effect on the bullet release. I run .002 neck tension on my rounds and do not crimp. I am not loading to magazine length. Even the type of primers could have a different effect (205M primers). I also trim the flash hole and normalize the primer pocket. I'm running David Tubb's AR-15 Carrier Weight System which delays the unlocking of the bolt. Suffice it to say that you should not just go with someone elses load but always work up your own. Spoken as a pistol kaboom survivor and a near kaboom in my rifle. Like with heart attacks, often the first warning sign is your last.
All the stuff you stated I doubt makes much difference til you said youre not seating to mag length. I was wondering how youre getting that much varget in there. Thatll make all the difference in the world, and my face is worth a lot to me so I never start at someone elses load. Ive seen way too many pictures of blown up firearms due to crappy reloading practices.
I ran my ladder up to 24.2 and pressure was starting to build a little but nothing bad. 23.8 grouped well, but was running out of daylight so my shots were a bit more quick than Id like. 3 shot group was well under and inch with damn near no vertical spread. Going to go back with some weight sorted brass, and more loads around my apparent 23.8gr accuracy node. May push it a little harder above 24.2 and see if I can find another node. Im using WSR primers so theyre fairly soft to begin with. Going to take my calipers with me and measure case web as well when I shoot the real heavy loads. I want mine to be mag fed so Im stuck with 2.24 COL unfortunately.
I ran my ladder up to 24.2 and pressure was starting to build a little but nothing bad. 23.8 grouped well, but was running out of daylight so my shots were a bit more quick than Id like. 3 shot group was well under and inch with damn near no vertical spread. Going to go back with some weight sorted brass, and more loads around my apparent 23.8gr accuracy node. May push it a little harder above 24.2 and see if I can find another node. Im using WSR primers so theyre fairly soft to begin with. Going to take my calipers with me and measure case web as well when I shoot the real heavy loads. I want mine to be mag fed so Im stuck with 2.24 COL unfortunately.
Here is a morsel of Information from another site. This if from a well known manufacturer mentioned on the hide. I am hesitant to mention their name as I just feel it may be inappropriate.
This is one of the rounds that got our company going.
Initially, as a garage handloader, I worked with up to 25 grains of Varget in Military brass. Around 24 grains was good for 5.56 pressures. Anything more, and primers started to pop occasionally.
As as a commercial loader, we've had success with Varget, H4895, and IMR 8208 XBR. The latter we switched to early, and have had great results with.
For MK262 type performance, i recommend starting around 23.2, and working up to 23.8 grains. We seat these at 2.250 max COAL, in military brass, with a CCI military or #450 primer. This is what we load our match ammo with, and it is outstanding. Our sponsored shooter used it along with our 308 to win the Summer Mammoth Sniper Challenge in 2011.
This is for 223 Wylde or 5.56 chambers only
This is one of the rounds that got our company going.
Initially, as a garage handloader, I worked with up to 25 grains of Varget in Military brass. Around 24 grains was good for 5.56 pressures. Anything more, and primers started to pop occasionally.
As as a commercial loader, we've had success with Varget, H4895, and IMR 8208 XBR. The latter we switched to early, and have had great results with.
For MK262 type performance, i recommend starting around 23.2, and working up to 23.8 grains. We seat these at 2.250 max COAL, in military brass, with a CCI military or #450 primer. This is what we load our match ammo with, and it is outstanding. Our sponsored shooter used it along with our 308 to win the Summer Mammoth Sniper Challenge in 2011.
This is for 223 Wylde or 5.56 chambers only
Yup.
23.5-23.8gr 8208XBR with a CCI-450 and a 77gr bullet...peas and carrots, peanut butter & jelly.
Tag because I have the exact same problem with same barrel and components. Will update when read through everything.
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Good to know my load is apparently right on with their recommendations. Just need to get a little more range time now with it.
I've tried Varget, TAC, PP 2000MR, RL 17, and even H4350 with the Hornady 75 BTHP. I CANNOT get the same accuracy as the BHA 77 SMK blue box load. This is not to say that I have not found some accurate loads. The BHA blue box shoots about .3 MOA pretty consistently. The rest of the stuff shoots around 1 MOA or less. All of this is with my 26" WOA 8 twist. I now have a box of 77 SMK's with the goofy cannulure, and just ordered 600 75 AMAXs from Wideners this am. The BHA blue box stuff is 1.850 to the ogive, and 2.247 COAL. The primer is silver outside and yellow priming compound similar to CCI. The powder is fine ball weighing 23.8 gr. The bullet has a fine cannulure (proper) that you can barely catch your fingernail on. It has a SIGNIFICANT crimp that took about 50 strikes with the kinetic hammer to break. The brass was LC '05. I'll post all of the other loads I worked up with the 75 BTHP Hornady.
The crimp is intresting,
Here is a load that shoots very well but yet is crimped, something that most people advocate against. I know for a fact that BH did alot of work with the military on producing a quality load. From all of my reading they use a temp stable ball powder with a flash supress agent. It is suspected to be tac, but is clearly not.
I have always used a Lee collet crip die for my autoloaders. My last load workup I crimped the exact same load and tested it agaisnt on non crimped version. The results are unclear as the base load sucks
I had some promising results with tac that turned out to be not all that impressive later.
Maybe if i can find any I would like to try 8208
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For the 75-77 class mag length ammo, from 23.2 - 24.0, you should find a good load for your set up. My rifles prefer 23.3 on bare 77s through Wylde chambers.
Here's some of the work I did the other day with the 77 SMK, and the 75 AMAX. I have modified a magpul magazine to get a longer COAL, as well as one of the old LR products single stack mags made by DPMS. Funny how the rifle seems to prefer stuff far away from the lands, and lower velocities. I have yet to try a crimp. It seems that the crimp on the BHA stuff helps keep the ES low. Everything BHA did with that ammo works together in concert VERY well. The difference between the LC brass and WIN brass, is the WIN brass is just a tad heavier, so the 23.8 of the TAC-ish in the LC brass from BHA, in my mind would be a higher charge that the WIN brass. Smaller container, higher pressure.
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Thanks for sharing, I have some 8208 to try next week, OCW is loaded
What length gun is that, There is no way thats a 18" with almost 3000 FPS ?
In looking at some of esorensen's earlier posts (just to find out the answer to same exact question) he has posted that he has a 26" WOA barrel on his AR, which accounts for the apparent anomalous high velocities he getting at those charge weights. So that explains it...
Really wish when people post velocities they'd post at least barrel length, twist and chamber especially when theyre using abnormal barrel lengths.
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I didn't think anyone who was following the thread would simply assume an 18" barrel.
Either way, you can see that velocities increase substantially when bullets are loaded close to the lands. In the case of the AMAX, the bullet was .005" before the lands. I was hoping for an accurate load in the 3K fps range, but I may have to settle for less. This is a coyote gun, so I'm more concerned with consistent accuracy. I'll figure out what she likes and then wring her out. My thoughts on the BHA load was if it is accurate in so many rifles, it more than likely can be modified, and components substituted with little or no loss in accuracy.
Either way, you can see that velocities increase substantially when bullets are loaded close to the lands. In the case of the AMAX, the bullet was .005" before the lands. I was hoping for an accurate load in the 3K fps range, but I may have to settle for less. This is a coyote gun, so I'm more concerned with consistent accuracy. I'll figure out what she likes and then wring her out. My thoughts on the BHA load was if it is accurate in so many rifles, it more than likely can be modified, and components substituted with little or no loss in accuracy.
Finally had a chance to run my load across the chrono. Averaged 2650 out of my 20" 7 twist white oak barrel. I also shot some blackhills 77gr to compare against and that averaged 2650 as well so my load is running pretty much right along with the BH loads. Accuracy has been pretty darn good as well at with average group sizes well under an inch.
As a update to my original post I have been working with 8208 XBR. I have found a load that is 1 MOA or slightly less at 2700 - 2725 out of a 18" gun
I still need to shoot this load in warmer temps before I commit to loading any quanity for further testing.
I will update this post as things progress
I still need to shoot this load in warmer temps before I commit to loading any quanity for further testing.
I will update this post as things progress
I posted a thread earlier but in my effort to edit it, I must have deleted it - chalk one up for the guy that's been here a while but doesn't post. I'll try things over again.
Lately I've been working with 8208XBR and 77 SMKs due to my inability to locate RE15 locally. The load that I use with RE15 is not a screaming load, it averages 2621 fps out of my suppressed 6920. The thing I like about it is the extreme spread (ES) is 11.9 fps. It's a good accurate load for my rifle. I load it with LC cases, Wolf small rifle magnum or CCI 41 primers (I found their is very little difference between them when chronographing) and a 2.260 COL. With this rifle and optic I'm able to shoot 1.25-1.35 moa at 100 yards (10 shot groups). I'm sure a better shooter, rifle and a little more magnification could make this load look a lot more accurate.
A little background - I primarily use the 77 SMKs to knock steel down at three gun matches I participate in where the ranges go out to 500 yards. The standard I set for my loads is I like the ES below 25 fps. Being that if your ES is 50 fps you're looking at around 1 MOA difference in impacts at 500 yards just due to your loads ability. With my capability, my rifles capability, shooting against the clock / other shooters I need all the help I can get. Especially now that I'm getting older and my eyes aren't as quick to adjust and eye fatigue sets in quicker.
As with most shooters that use RE15, I'm having a problem finding it locally. A few weeks ago I was down to my last dregs and decided I need to find another available powder. I wasn't getting the velocity or ES I wanted with ARCOMP, and the next powder to try was 8208 XBR. My local gun shop has it in stock, although I noted it went up $2 per lb to $22.95 per lb. Still not a bad price.
A few notes about my rifle and testing. My rifle is pretty much a bone stock 6920 with a Knights rail, Leupold Mk 4 MR/T with the CMR2 reticle and a Surefire muzzle brake / suppressor mount. When I chronograph I have my Surefire 556-212 suppressor attached to my rifle. I find it cuts down on off the wall readings and shots not being picked up. With the can on, I note an increase in velocity of about 50 FPS depending on the load. With XBR I started at the bottom of the suggested load chart and worked up with one load that exceeded the maximum recommended load, by not much, but I won't say what it was for safety sake even through there weren't any extreme pressure signs - more about that later. The lower end loads did not meet my ES requirements until I started hitting the upper end of the loads.
Here are my results with XBR - All loads were 2.260 COL, and Wolf SRM primers and LC 09 cases.
23.0 gr XBR
SD: 20.2
ES 58.1
AVE: 2596.0
23.2 gr XBR (maximum listed load)
SD: 10
ES: 21.3
AVE: 2650.0
23.X gr XBR (slightly above maximum listed load)
SD: 23.0
ES: 61.9
AVE: 2663.8
All chronographing was done with 10 rounds per load and the day I was shooting it was 26 degrees out with the screens 10' in front of the muzzle. My groups with the 23.2 load were about 1.4-1.5 moa with 10 shot groups. I blame the groups on me - the numbers on the load appear consistent. I was getting kind of cold. When the weather gets better, I'm going to shoot some of these loads for grouping.
When shooting with the suppressor attached, I've noted I usually get ejector marks on the cases when things are getting warm even with the H2 buffer. Even with M193 and 885 I routinely get ejector marks depending on the lot of ammo. Below are two of the cases with my 23.2 gr XBR loads. Yes, there's ejector marks but, the primers still look like they are nicely rounded - I'm aware that primers aren't the end all determiner of high pressure, but it's my opinion that these still look good. Yes, the cases are dark. Suppressors are dirty!
I think it's interesting that just above and below 23.2 grains of XBR there are wildly different results in the ES and SD of the loads. On both sides of 23.2 gr the loads are unacceptable to me with their ES. I'm kind of liking the 23.2 grain load, but not as much as the RE15 load...yet.
I still have enough 77 SMKs loaded with RE15 to last me till summer. I'm going to test the XBR loads when I go out to the Whittington Center this summer to instruct rifle marksmanship. I'm sure it will be a little warmer than 26 degrees! Probably at least the high 90s for a few days. I'm anxious to work with 8208XBR some more!
Lately I've been working with 8208XBR and 77 SMKs due to my inability to locate RE15 locally. The load that I use with RE15 is not a screaming load, it averages 2621 fps out of my suppressed 6920. The thing I like about it is the extreme spread (ES) is 11.9 fps. It's a good accurate load for my rifle. I load it with LC cases, Wolf small rifle magnum or CCI 41 primers (I found their is very little difference between them when chronographing) and a 2.260 COL. With this rifle and optic I'm able to shoot 1.25-1.35 moa at 100 yards (10 shot groups). I'm sure a better shooter, rifle and a little more magnification could make this load look a lot more accurate.
A little background - I primarily use the 77 SMKs to knock steel down at three gun matches I participate in where the ranges go out to 500 yards. The standard I set for my loads is I like the ES below 25 fps. Being that if your ES is 50 fps you're looking at around 1 MOA difference in impacts at 500 yards just due to your loads ability. With my capability, my rifles capability, shooting against the clock / other shooters I need all the help I can get. Especially now that I'm getting older and my eyes aren't as quick to adjust and eye fatigue sets in quicker.
As with most shooters that use RE15, I'm having a problem finding it locally. A few weeks ago I was down to my last dregs and decided I need to find another available powder. I wasn't getting the velocity or ES I wanted with ARCOMP, and the next powder to try was 8208 XBR. My local gun shop has it in stock, although I noted it went up $2 per lb to $22.95 per lb. Still not a bad price.
A few notes about my rifle and testing. My rifle is pretty much a bone stock 6920 with a Knights rail, Leupold Mk 4 MR/T with the CMR2 reticle and a Surefire muzzle brake / suppressor mount. When I chronograph I have my Surefire 556-212 suppressor attached to my rifle. I find it cuts down on off the wall readings and shots not being picked up. With the can on, I note an increase in velocity of about 50 FPS depending on the load. With XBR I started at the bottom of the suggested load chart and worked up with one load that exceeded the maximum recommended load, by not much, but I won't say what it was for safety sake even through there weren't any extreme pressure signs - more about that later. The lower end loads did not meet my ES requirements until I started hitting the upper end of the loads.
Here are my results with XBR - All loads were 2.260 COL, and Wolf SRM primers and LC 09 cases.
23.0 gr XBR
SD: 20.2
ES 58.1
AVE: 2596.0
23.2 gr XBR (maximum listed load)
SD: 10
ES: 21.3
AVE: 2650.0
23.X gr XBR (slightly above maximum listed load)
SD: 23.0
ES: 61.9
AVE: 2663.8
All chronographing was done with 10 rounds per load and the day I was shooting it was 26 degrees out with the screens 10' in front of the muzzle. My groups with the 23.2 load were about 1.4-1.5 moa with 10 shot groups. I blame the groups on me - the numbers on the load appear consistent. I was getting kind of cold. When the weather gets better, I'm going to shoot some of these loads for grouping.
When shooting with the suppressor attached, I've noted I usually get ejector marks on the cases when things are getting warm even with the H2 buffer. Even with M193 and 885 I routinely get ejector marks depending on the lot of ammo. Below are two of the cases with my 23.2 gr XBR loads. Yes, there's ejector marks but, the primers still look like they are nicely rounded - I'm aware that primers aren't the end all determiner of high pressure, but it's my opinion that these still look good. Yes, the cases are dark. Suppressors are dirty!
I think it's interesting that just above and below 23.2 grains of XBR there are wildly different results in the ES and SD of the loads. On both sides of 23.2 gr the loads are unacceptable to me with their ES. I'm kind of liking the 23.2 grain load, but not as much as the RE15 load...yet.
I still have enough 77 SMKs loaded with RE15 to last me till summer. I'm going to test the XBR loads when I go out to the Whittington Center this summer to instruct rifle marksmanship. I'm sure it will be a little warmer than 26 degrees! Probably at least the high 90s for a few days. I'm anxious to work with 8208XBR some more!
RPrecision,
We are working along similar lines. No worries on thermal stability of IMR 8208 as used in 5.56MM. The 77gr. SMK over 5.56MM pressure IMR 8208 tested to have only 0.1 FPS/1 degree F MV variation from -10F to +135F in 18" Krieger/CLE barrel. The IMR 8208 load is 80 FPS slower than the factory BHA MK 262 MOD 1 tactical load but the 8208 load is just a bit more accurate at 100yds.. The ES/SD is quite small with 8208 so hoping to reduce vertical stringing on LR loads.
We are working along similar lines. No worries on thermal stability of IMR 8208 as used in 5.56MM. The 77gr. SMK over 5.56MM pressure IMR 8208 tested to have only 0.1 FPS/1 degree F MV variation from -10F to +135F in 18" Krieger/CLE barrel. The IMR 8208 load is 80 FPS slower than the factory BHA MK 262 MOD 1 tactical load but the 8208 load is just a bit more accurate at 100yds.. The ES/SD is quite small with 8208 so hoping to reduce vertical stringing on LR loads.
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Bullet seating
The reason for the 2.245" seating depth was to reduce bullet run out......
The reason for the 2.245" seating depth was to reduce bullet run out......
Is it against the rules/COC to post pics of chrono data with groups. I have three sessions starting at the book max of 23.2gr of 8208/77gr NOS/16"bbl/ar and going up from there.
Yes please post, I just got a jug of 8208xbr and 1k of the nos77's , trying to find a universal load for my 20" bbl'd RRA 7 twist and my 26" Mcgowan barreled Sav 10FP.
Please post.
Im loading 22.9 of XBR, Nos 77 CC at 2.26 COAL, WSRP, WCC 1X cases for a 16" LMT. I picked this load based on my opinion of how it hit on paper. Would be great to get some real data.
I posted a thread earlier but in my effort to edit it, I must have deleted it - chalk one up for the guy that's been here a while but doesn't post. I'll try things over again.
Lately I've been working with 8208XBR and 77 SMKs due to my inability to locate RE15 locally. The load that I use with RE15 is not a screaming load, it averages 2621 fps out of my suppressed 6920. The thing I like about it is the extreme spread (ES) is 11.9 fps. It's a good accurate load for my rifle. I load it with LC cases, Wolf small rifle magnum or CCI 41 primers (I found their is very little difference between them when chronographing) and a 2.260 COL. With this rifle and optic I'm able to shoot 1.25-1.35 moa at 100 yards (10 shot groups). I'm sure a better shooter, rifle and a little more magnification could make this load look a lot more accurate.
A little background - I primarily use the 77 SMKs to knock steel down at three gun matches I participate in where the ranges go out to 500 yards. The standard I set for my loads is I like the ES below 25 fps. Being that if your ES is 50 fps you're looking at around 1 MOA difference in impacts at 500 yards just due to your loads ability. With my capability, my rifles capability, shooting against the clock / other shooters I need all the help I can get. Especially now that I'm getting older and my eyes aren't as quick to adjust and eye fatigue sets in quicker.
As with most shooters that use RE15, I'm having a problem finding it locally. A few weeks ago I was down to my last dregs and decided I need to find another available powder. I wasn't getting the velocity or ES I wanted with ARCOMP, and the next powder to try was 8208 XBR. My local gun shop has it in stock, although I noted it went up $2 per lb to $22.95 per lb. Still not a bad price.
A few notes about my rifle and testing. My rifle is pretty much a bone stock 6920 with a Knights rail, Leupold Mk 4 MR/T with the CMR2 reticle and a Surefire muzzle brake / suppressor mount. When I chronograph I have my Surefire 556-212 suppressor attached to my rifle. I find it cuts down on off the wall readings and shots not being picked up. With the can on, I note an increase in velocity of about 50 FPS depending on the load. With XBR I started at the bottom of the suggested load chart and worked up with one load that exceeded the maximum recommended load, by not much, but I won't say what it was for safety sake even through there weren't any extreme pressure signs - more about that later. The lower end loads did not meet my ES requirements until I started hitting the upper end of the loads.
Here are my results with XBR - All loads were 2.260 COL, and Wolf SRM primers and LC 09 cases.
23.0 gr XBR
SD: 20.2
ES 58.1
AVE: 2596.0
23.2 gr XBR (maximum listed load)
SD: 10
ES: 21.3
AVE: 2650.0
23.X gr XBR (slightly above maximum listed load)
SD: 23.0
ES: 61.9
AVE: 2663.8
All chronographing was done with 10 rounds per load and the day I was shooting it was 26 degrees out with the screens 10' in front of the muzzle. My groups with the 23.2 load were about 1.4-1.5 moa with 10 shot groups. I blame the groups on me - the numbers on the load appear consistent. I was getting kind of cold. When the weather gets better, I'm going to shoot some of these loads for grouping.
When shooting with the suppressor attached, I've noted I usually get ejector marks on the cases when things are getting warm even with the H2 buffer. Even with M193 and 885 I routinely get ejector marks depending on the lot of ammo. Below are two of the cases with my 23.2 gr XBR loads. Yes, there's ejector marks but, the primers still look like they are nicely rounded - I'm aware that primers aren't the end all determiner of high pressure, but it's my opinion that these still look good. Yes, the cases are dark. Suppressors are dirty!
I think it's interesting that just above and below 23.2 grains of XBR there are wildly different results in the ES and SD of the loads. On both sides of 23.2 gr the loads are unacceptable to me with their ES. I'm kind of liking the 23.2 grain load, but not as much as the RE15 load...yet.
I still have enough 77 SMKs loaded with RE15 to last me till summer. I'm going to test the XBR loads when I go out to the Whittington Center this summer to instruct rifle marksmanship. I'm sure it will be a little warmer than 26 degrees! Probably at least the high 90s for a few days. I'm anxious to work with 8208XBR some more!
Henry,
Have you tried different primers to lower your ES? Maybe try using Rem 7 1/2.
I run 23.5gr 8208XBR under a 77gr Nosler in my 18" FrankenSPR and get roughly 2660fps.
23.8gr comes within a couple FPS +/- of Black Hills 5.56 77gr OTM white box seconds in my rifle.
The 23.5gr load is a fuzz more accurate than 23.8gr, but 23.8 is still MOA or better.
23.8gr comes within a couple FPS +/- of Black Hills 5.56 77gr OTM white box seconds in my rifle.
The 23.5gr load is a fuzz more accurate than 23.8gr, but 23.8 is still MOA or better.
7 1/2s are like hen's teeth around my home area. I have CCI 34s, 400s, 450s and the Wolf SRM223s. When I was working with RE15 I found the Wolf primers to give me more consistent velocities. Perhaps I should go revisit my loads and switch up primers.
Sometimes I just get on one track and stay there. Since that post, I've been pretty happy with the 23.2gr load. I'll have to switch up primers and see if things improve any.
