New 6mm Advanced Rifle Cartridge

[ormandj]

So question for the reloading experts:

most of the powders we are discussing - CFE223, Leverevolution, N540, BLC2, 2520, etc - are all very close to each other on the burn chart. So why does the pressure curve look different? Is it because of differences in volumetric characteristics of each? For example, does CFE223 have a lower volume requirement than say N540, allowing it to produce lower initial pressure and then generate 'push' further down the barrel?

RE the questions on magazines from @DeSnifter - I can't recommend ASC mags. I'm getting some FTFs w/ them... maybe its something else, not the mag, but its spotty right now.

Burn rate is not linear with pressure. Different powders have different additives and properties which lead to vastly different pressure curves/behaviors. Couple that with cartridge designs and the whole world of internal ballistics and you end up with needing a lot of powder to experiment with to figure out what's best. Burn rate generally gives you a good idea what powders to look at for your goals, assuming you have some starting pressure data from the manufacturer, but beyond that, experimentation is key.

The only thing that sucks about this situation is you can't rely on pressure signs to tell you when you've hit the 52kpsi limit and then back down with cartridges with this size bolt-face requirement; by the time you see pressure signs you're already over the cartridge limit. It's not likely to be destructive immediately, but the bolt will probably wear out more rapidly than ideal. So we have to rely on manufacturer data then try to approximate where powders not tested fall.

 

[Yondering]

The only thing that sucks about this situation is you can't rely on pressure signs to tell you when you've hit the 52kpsi limit and then back down with cartridges with this size bolt-face requirement; by the time you see pressure signs you're already over the cartridge limit. It's not likely to be destructive immediately, but the bolt will probably wear out more rapidly than ideal. So we have to rely on manufacturer data then try to approximate where powders not tested fall.

Yes, but with the powders we're recommending here, you can work up to pressure signs without damaging the bolt, and back off from there. (I say with these powders because there's always someone who wants to use a powder that's way too fast in burn rate, and the pressure spikes might damage the bolt before brass damage is evident. Shock damage of hard steel can happen over a much shorter time period than plastic deformation of soft materials like cartridge brass.) I'm speculating a little bit here, that's why I say "might", because I choose powders of the correct burn rate.

 

[MSTN]

The new November 2020 "American Rifleman" has an article on the 6mm ARC.

To me, the most interesting line in it was "...the DOD was still searching for a bridge chambering between the 5.56 mm NATO and the 7.62x51 NATO that could counter an evolving enemy that, by proxy and via experience, has become proficient in riflery to about 600 yards."

 

[towerofpower93]

The new November 2020 "American Rifleman" has an article on the 6mm ARC.

To me, the most interesting line in it was "...the DOD was still searching for a bridge chambering between the 5.56 mm NATO and the 7.62x51 NATO that could counter an evolving enemy that, by proxy and via experience, has become proficient in rifler to about 600 yards."

Not sure I'd say the enemy "has become proficient in rifler to about 600yds" but more like they've figured out they can lob rounds from far off to reduce their chances of receiving a 62gr foreign aid package.

 

[jbailey]

Burn rate is not linear with pressure. Different powders have different additives and properties which lead to vastly different pressure curves/behaviors.

Thanks @ormandj
so there are more variables than just burn rate and volume...

I will continue to practice safe reloading, as I'm relatively novice at reloading for a gas gun. I have a lb. of CFE223 inbound and I have backed off my N540 load a good amount. I will use this N540 load at a fun match I'm hosting on my farm next weekend and then get back to load development, looking for a bit more MV at lower pressures.

 

[Henryrifle]

Took the 6mm ARC hunting yesterday and brought along a 6.5 Creedmoor bolt rifle. Never unzipped the bolt gun's case! Harvested 4 small to medium sized Georgia does. Shot distance was from 100 yards to 250 yards using the Hornady 108 ELD-M with a muzzle velocity of 2670. Three dropped at the spot and one less than 25 yards from impact. The bullet and rifle performed superbly.

To minimize searching, my rifle has a 21.75" barrel that I profiled down to 1" in diameter and a .875 gas block. This makes for a heavy rifle and adding a suppressor required careful handling in the blind due to overall weight and length. This isn't all bad as it forced very intentional movement with all rifle placement activities, however, I am thinking about making a new barrel for hunting that would be much lighter and likely 18".

Very happy with the cartridge and rifle at this point. It is a decent shooter with .7 MOA accuracy, reasonable velocity for deer at short/medium-short range and easily capable of ringing 1 MOA steel at 1000 yards. A lot of cartridges can do that, I know, but not many in a AR-15 platform.

Henryrifle

 

[LRBuck]

Took the 6mm ARC hunting yesterday and brought along a 6.5 Creedmoor bolt rifle. Never unzipped the bolt gun's case! Harvested 4 small to medium sized Georgia does. Shot distance was from 100 yards to 250 yards using the Hornady 108 ELD-M with a muzzle velocity of 2670. Three dropped at the spot and one less than 25 yards from impact. The bullet and rifle performed superbly.

To minimize searching, my rifle has a 21.75" barrel that I profiled down to 1" in diameter and a .875 gas block. This makes for a heavy rifle and adding a suppressor required careful handling in the blind due to overall weight and length. This isn't all bad as it forced very intentional movement with all rifle placement activities, however, I am thinking about making a new barrel for hunting that would be much lighter and likely 18".

Very happy with the cartridge and rifle at this point. It is a decent shooter with .7 MOA accuracy, reasonable velocity for deer at short/medium-short range and easily capable of ringing 1 MOA steel at 1000 yards. A lot of cartridges can do that, I know, but not many in a AR-15 platform.

Henryrifle

That’s great Henryrifle! Did you load with CFE 223? It sounds like it from your velocity.
How did the ELD m perform as a hunting round?
I plan to work up a load with the 103 ELD x in either Varget or AR Comp for deer 300yards or less.
Did you ever start working with AR Comp? If so what results?

 

[Henryrifle]

By default, I guess I've settled on CFE 223--that was good insight on your part. The weather is getting much cooler here in Georgia--it was 36 degrees this morning--and I am curious to see what that will do to MV and what adjustment in charge weight will be necessary.

I have not hunted with the ELD-M before but, know guys who have successfully. I was pumped (relieved to be honest) to see the deer drop at the site of impact. We stopped hunting at 6:00pm yesterday and it was too dark to take pictures as we loaded them into the truck. Shot placement, however, was very good on each animal. Was glad to see that too as I realized I have become so accustomed to prone shooting that I had to work hard to get the rifle stable seated in the blind. Another example of where you need to practice like you play. Even at 300 yards the 108 retains 1150 ft-lbs of energy. That should be plenty to put down even a bigger deer. That said, I don't have a great answer to your question yet and was very much thinking about putting together a 103 ELD-X load myself. Going to order some when I finish this reply.

I have not tried AR Comp yet and while I hate to admit being lazy, might not make the effort as the CFE 223 is doing so well. I know you are thinking about the 103 but I was only able to get about 2590 FPS out of Varget + the 108, and nominally, it was more like 2575 FPS. That gives me about 1080 lb-ft of energy at 300 yards and while acceptable it adds pressure to make a really good shot. You'll get a little more speed out of the 103.

Henryrifle

 

[NH4X]

@Henryrifle ......good report thx.....sounds like ya'll had a good thinning going on. I used the 108 eldm bullet last year, out of a 6 cm @3050 .....all deer and 1 hog hit the ground where/ when shot. All shots 300/ 350 yds. Im not planning on changing bullets this year. Im planning to build a 6arc upper pretty close to what you have ( im going 24 inch barrel)....... Thanks to all who have shared their data in this thread.......it'll help out a lot when i get started.

 

[Ndbowhunter]

Stay with the 108’s.. my 243 bolt gun doesn’t push them much faster with 4350 then what a 20” ARC gets with lever.

108’s hammer deer. 24” plus of penetration quartering to through front shoulder and exit out of abdominal on a big mule deer. Absolute carnage through wound track.

 

[LRBuck]

Stay with the 108’s.. my 243 bolt gun doesn’t push them much faster with 4350 then what a 20” ARC gets with lever.

108’s hammer deer. 24” plus of penetration quartering to through front shoulder and exit out of abdominal on a big mule deer. Absolute carnage through wound track.

Good to know how the 108 performs as a hunting round on deer. I have them in factory ammo but not any for reloading. Only the 103s and Berger LR hybrid in 109s. If anyone had tried 109s please post.
If the factory 108s prove accurate in my rifle they will certainly be used that way. Hopefully my barrel from Craddock will be here soon (or at least before deer season is over) and I will get to find out. I have some CFE 223 so all the data that has been provided so far (thanks again) will be a great help.

 

[newageroman]

What's up guys - lurker here. Just tested some Hornady brass at @2550and starline @2430 using Berger 105s and ppVarmit. (following Johnny). Have CFE223 to try next.

 

[TexasRL]

I have a 6mm ARC with a Sanders Armory 20" upper in 7.5 twist. Using handloads of 105gr Berger VLD Match (HPBT) with 27.9 gr CFE 223 at 0.06" off the lands comes in at just under 0.75 MOA at 100 yards. Still playing with ladders to see what else I can find that might be better. I bought a batch of Factory 2nds that look like 103 gr Hornady ELD-X's, and want to find a good load for hunting purposes, but I'm not finding any published data. I don't have access to a good ballistics calculator that will calculate pressure, so my plan was to carefully extrapolate from Hornady's data between the 100 gr and 105 gr, erring on the cautious side, and watching for any pressure signs while working from low to high, hopefully finding a good node in the mid-range. I plan to try both Varget and CFE 223 to see what I find. But, before I do that, I wanted to see if anyone on the forum had already worked up anything or knew of a better way to extrapolate and keep things in the safe region.

 

[rjh]

I have a 6mm ARC with a Sanders Armory 20" upper in 7.5 twist. Using handloads of 105gr Berger VLD Match (HPBT) with 27.9 gr CFE 223 at 0.06" off the lands comes in at just under 0.75 MOA at 100 yards. Still playing with ladders to see what else I can find that might be better. I bought a batch of Factory 2nds that look like 103 gr Hornady ELD-X's, and want to find a good load for hunting purposes, but I'm not finding any published data. I don't have access to a good ballistics calculator that will calculate pressure, so my plan was to carefully extrapolate from Hornady's data between the 100 gr and 105 gr, erring on the cautious side, and watching for any pressure signs while working from low to high, hopefully finding a good node in the mid-range. I plan to try both Varget and CFE 223 to see what I find. But, before I do that, I wanted to see if anyone on the forum had already worked up anything or knew of a better way to extrapolate and keep things in the safe region.

You can download Gordon reloading tools, it is a free ballistic program. Similar in function to quickload and 6mm arc is in the program. I am about to work up a load for 95 gr vlds
.

 

[Henryrifle]

@TexasRL:

I am a big fan of Varget but don't think that it is a good powder for 103 grain and heavier projectiles in our 6mm ARCs. I wanted it to work but always hit pressure before minimum target MV. Just not enough energy to get them going fast enough. If mid 2500 FPS works for you then Varget is okay.

Bullet design and specifically bearing surface can have a big impact on pressure and therefore velocity. That said, you should be safe experimenting in the same powder ranges with your 103s as you are with your 105s. By the way, what is the MV of your 105 VLD load with 27.9 grains CFE 223? Guessing it is around 2575?

It is not difficult to see pressure signs in an AR when you are at or above pressure. I don't mean to presume that you don't know this but, It starts with a shiny swipe on the back of the brass. Next you see the round outline of the ejector and finally you get both the shiny swipe and ejector mark plus a raised burr.

The good news is that the 52K psi limit seems very safe as it aims to maximize bolt life and overall reliability of the operating system. A few excursions over 52K in testing shouldn't be damaging. This is my opinion and not a guarantee, suggestion or advice.

Lots of good data coming out now from different places!

Henryrifle

 

[TexasRL]

You can download Gordon reloading tools, it is a free ballistic program. Similar in function to quickload and 6mm arc is in the program. I am about to work up a load for 95 gr vlds
.

Thanks for the advice. I downloaded it. Only problem is they don't have the 103 gr ELD-X in their database. I will have to play with it a bit and will try to add it in. Thanks!!!

 

[TexasRL]

@TexasRL:

I am a big fan of Varget but don't think that it is a good powder for 103 grain and heavier projectiles in our 6mm ARCs. I wanted it to work but always hit pressure before minimum target MV. Just not enough energy to get them going fast enough. If mid 2500 FPS works for you then Varget is okay.

Bullet design and specifically bearing surface can have a big impact on pressure and therefore velocity. That said, you should be safe experimenting in the same powder ranges with your 103s as you are with your 105s. By the way, what is the MV of your 105 VLD load with 27.9 grains CFE 223? Guessing it is around 2575?

It is not difficult to see pressure signs in an AR when you are at or above pressure. I don't mean to presume that you don't know this but, It starts with a shiny swipe on the back of the brass. Next you see the round outline of the ejector and finally you get both the shiny swipe and ejector mark plus a raised burr.

The good news is that the 52K psi limit seems very safe as it aims to maximize bolt life and overall reliability of the operating system. A few excursions over 52K in testing shouldn't be damaging. This is my opinion and not a guarantee, suggestion or advice.

Lots of good data coming out now from different places!

Henryrifle

For the CFE 223 5-shot group, MV was 2531. I fully agree on the Varget - I was hoping to find good rounds, but no luck thus far. The CFE 223 just fell into my lap. Pretty much the full range of what I loaded to test came out shooting pretty good, so with my son coming into town, I wanted to make some plinking rounds (with the idea to save the Hornady Black for myself when getting serious. I opted to go middle of the pack since they were all shooting pretty good, and that's why I settled on the 27.9 gr. I really was just using the rounds to make sure I was sighted in well before shooting some ladders, but was pleasantly surprised with the results. Still plan to keep working on it. My ladders weren't what I expected, so I plan to load a new batch this week to hit the range with.

 

[Dino11]

Having worked with CFE223 and a couple other powders the best that I have come across to date is Leverevolution. It is a mix of both velocity and accuracy shooting in the 2600 to 2650FPS and .5 MOA with Nosler 105 RDF's. Next I am going to try BLC 2, it falls between CFE223 and Lever.

 

[Yondering]

@TexasRL:

I am a big fan of Varget but don't think that it is a good powder for 103 grain and heavier projectiles in our 6mm ARCs. I wanted it to work but always hit pressure before minimum target MV. Just not enough energy to get them going fast enough. If mid 2500 FPS works for you then Varget is okay.

Bullet design and specifically bearing surface can have a big impact on pressure and therefore velocity. That said, you should be safe experimenting in the same powder ranges with your 103s as you are with your 105s. By the way, what is the MV of your 105 VLD load with 27.9 grains CFE 223? Guessing it is around 2575?

It is not difficult to see pressure signs in an AR when you are at or above pressure. I don't mean to presume that you don't know this but, It starts with a shiny swipe on the back of the brass. Next you see the round outline of the ejector and finally you get both the shiny swipe and ejector mark plus a raised burr.

The good news is that the 52K psi limit seems very safe as it aims to maximize bolt life and overall reliability of the operating system. A few excursions over 52K in testing shouldn't be damaging. This is my opinion and not a guarantee, suggestion or advice.

Lots of good data coming out now from different places!

Henryrifle

Some of the "pressure signs" you're talking about are really signs of the rifle being overgassed. Varget is capable of much better velocity than you're getting (although I didn't get good accuracy from it) but if your rifle is overgassed it'll make the brass look like it's overpressure. Swipes in particular are a timing (overgassed) sign. Excessive shoulder bump can do the same, including permanent ejector hole marks.

I was seeing mid-2700 fps with my 24" barrel and the 105gr BTHP over Varget, with no brass issues at all. That'd be about the top end of what Varget can do, but it's a big difference from 2500.

I say that despite not being a fan of Varget. I've never found a load I couldn't do better with a different powder; just my experience.

 

[Henryrifle]

Thank you @Yondering. I have a lot to learn about ARs -- I know. Glad you added some examples of where my observations are not necessarily the right conclusion.

I always shoot suppressed to minimize the complaining from neighbors which necessitates the use of adjustable gas blocks. My method for 'tuning,' and, I admit that this is likely very basic, is to continue to restrict gas through the gas port/gas block until the bolt either does not lock open on the last round out of the magazine or the bolt fails to strip off and chamber the next round from the magazine. Once I find that spot I open the gas port a click or two and never really check it again as long as the rifle functions properly. I do understand that there is a relationship between pressure and velocity and that restricting the gas port probably doesn't do exactly what I think it does.

With regards to sizing the brass, I always bump the brass back at least .003" and a maximum of .005."

I have on occasion played around with heaver buffers and buffer springs but don't possess any knowledge about how that might make tuning better or worse other than the intuitive idea that a heavier buffer and/or spring might slow things down a bit.

Will search for more advanced understanding of tuning.

Thank you again,
Henryfifle

 

[MSTN]

Your gas block adjusting technique is I think 100% solid. This is right where I coincidentally seem to get the best accuracy, as well.

 

[Yondering]

Thank you @Yondering. I have a lot to learn about ARs -- I know. Glad you added some examples of where my observations are not necessarily the right conclusion.

I always shoot suppressed to minimize the complaining from neighbors which necessitates the use of adjustable gas blocks. My method for 'tuning,' and, I admit that this is likely very basic, is to continue to restrict gas through the gas port/gas block until the bolt either does not lock open on the last round out of the magazine or the bolt fails to strip off and chamber the next round from the magazine. Once I find that spot I open the gas port a click or two and never really check it again as long as the rifle functions properly. I do understand that there is a relationship between pressure and velocity and that restricting the gas port probably doesn't do exactly what I think it does.

With regards to sizing the brass, I always bump the brass back at least .003" and a maximum of .005."

I have on occasion played around with heaver buffers and buffer springs but don't possess any knowledge about how that might make tuning better or worse other than the intuitive idea that a heavier buffer and/or spring might slow things down a bit.

Will search for more advanced understanding of tuning.

Thank you again,
Henryfifle

You're doing it right with the gas block, that is 100% correct. (One never knows here though, some guys just run the rifle severely overgassed and never consider it - my apologies for the assumption.)

Something to keep in mind though is the suppressed bit; that changes things a little, in relation to the tendency to cause swipes as you crank up the load it happens sooner and seems to become overgassed a bit quicker than you'd expect without running suppressed. It's likely that tightening a few clicks in on your gas block would get rid of the swipes as you turn up the heat on the load, so to speak.

Sometimes a heavy buffer can help a little when you're switching a lot between suppressed and unsuppressed. Most of the time IMO if you're either suppressed or unsuppressed 100% of the time, and not switching, the heavier buffer weights don't offer any advantage when you're tuning the gas system anyway. Of course there are always exceptions, but my preference (since I tune the gas block or port size as well) is to stick with a standard carbine buffer weight and just set the gas correctly. More mass in the buffer is noticeable when the bcg locks up again, more of a thump in the forward direction.

Since you're setting the shoulder bump correctly, a permanent ejector hole mark on the brass (a raised bump, not necessarily a swipe if timing is good) is a pretty good indicator that pressure is getting up there a bit, or brass is pretty soft. Either way it is a good indication to back down the load for use in that brass.

Sounds like other than maybe the gas tuning for the hotter load, you're doing everything else right so it's interesting that I was able to get so much more velocity from Varget.

 

[jbailey]

Great comments guys. Thanks much. Learning a lot.

I'm seeing overgassed results w/ my 6ARC w/o an adjustable block. So I added a Superlative Arms adjustable block but I overtightened it in 'off' which caused the adjustment screw to strip out - mo'fo!!!! Nicely, the loads that were showing pressure in the overgassed state aren't showing these signs now w/o gas. Load is 27.6gr N540, 105gr Berger, 54*F = 2600fps (SD = 10fps) from 20" of barrel, still with good precision (groups under 0.7" at 100). This is getting there!

Anyway, I'm looking to fix that gas block and get back to load development. It is fun to learn all this stuff about finer details on a DI gas system.

 

[Yondering]

Nicely, the loads that were showing pressure in the overgassed state aren't showing these signs now w/o gas.

Yup, great example how classic "pressure signs" aren't really pressure signs at all. That's why I often refer to that stuff as false pressure signs. Glad you saw it first hand!

On the stripped out gas block screw - assuming it's the hex key hole that stripped out, sometimes you can get the screw out by using the next size up Torx bit, or even just the correct size (Torx sizes are numbered different, but actually fit some of the standard hex screw sizes correctly). If you have the next size up that's just a little oversized, you can tap it partly into the hex with a hammer, and then unscrew it. Don't go overboard though.

 

[ormandj]

What neck wall thickness are people seeing they need to turn the Hornady brass down to get uniformity?

 

[Ledzep]

Unless you're really trying to compete in BR of F-Class I wouldn't burn up time neck turning. With my mixed lot 1-7x fired cases (from factory ammo originally) that I simply resize, trim, and load I shot a 3/4 MOA 20-shot group the other day.

ETA: That was a bolt gun. You'd really have to start paying me well to neck turn semi-auto cases.

 

[jbailey]

On the stripped out gas block screw - assuming it's the hex key hole that stripped out, sometimes you can get the screw out by using the next size up Torx bit, or even just the correct size (Torx sizes are numbered different, but actually fit some of the standard hex screw sizes correctly). If you have the next size up that's just a little oversized, you can tap it partly into the hex with a hammer, and then unscrew it. Don't go overboard though.

Thanks for this advice. Appreciate it.
I tried this w/o success. Then I ground a line across it with a Dremel and tried a flathead screw driver and then an impact gun. No luck. I'm done messing with it and threw it in trash bin. New one is in mail. (My time is more valuable than a few $s.)

If there is a way to break something, I usually find it.

 

[ormandj]

Unless you're really trying to compete in BR of F-Class I wouldn't burn up time neck turning. With my mixed lot 1-7x fired cases (from factory ammo originally) that I simply resize, trim, and load I shot a 3/4 MOA 20-shot group the other day.

ETA: That was a bolt gun. You'd really have to start paying me well to neck turn semi-auto cases.

I appreciate the info, but I'm still interested in thickness people are seeing when trimmed down to uniformity. Neck turning is fast for me on a powered lathe with a fixture so I do it for bolt/semi/everything. I'm just trying to make sure I'm not seeing an anomaly. I realize for many people it doesn't make sense, but I'm trying to wring what accuracy I can out of this and see how it does.

 

[LRBuck]

I appreciate the info, but I'm still interested in thickness people are seeing when trimmed down to uniformity. Neck turning is fast for me on a powered lathe with a fixture so I do it for bolt/semi/everything. I'm just trying to make sure I'm not seeing an anomaly. I realize for many people it doesn't make sense, but I'm trying to wring what accuracy I can out of this and see how it does.

I wish I could help you on that.
Ormandj, did you ever test AR Comp?
I saw you sold some and was curious if that was because it didn’t perform in the 6 ARC like you hoped. Wondering if I need to take it off my list of powder to try. If you did try it, what results?

 

[ormandj]

I wish I could help you on that.
Ormandj, did you ever test AR Comp?
I saw you sold some and was curious if that was because it didn’t perform in the 6 ARC like you hoped. Wondering if I need to take it off my list of powder to try. If you did try it, what results?

It's fine, accuracy was fine, but I couldn't trust that I wasn't pushing pressures into unsafe levels, so I sold off 16lbs until I get a pressure testing system in. I'll revisit it when I can ensure I'm staying under 52kpsi with the velocity I want, but especially with my 10.5" barrel, every FPS counts. The 18" it would have been fine in. Seeing I can consistently hit 2320fps with the factory ammunition in 108gr out of the 10.5" has opened up some possibilities for uses for me, so I'm about to try CFE223 and LVR and see how they do since they should be able to get me in the same ballpark range.

I'm going to see if temperature has much impact in this cartridge, as I'm still wary of using powders like this when I care about accuracy. It won't matter for guys who are fine with 1/2 MOA, or shooting bolt guns where rounds don't sit in a hot chamber for long, but I'm aiming for better. I don't like first-round flyers. As long as it's reasonable enough to be fine for non-target re: temp sensitivity (hunting, for example) then that'll be ok, as noted above I can compensate for temperature with a ballistic solver. I do have concerns about seasonal variation, I don't want to be leaving 75fps on the table between summer and winter, but we'll see.

 

[Yondering]

I'm going to see if temperature has much impact in this cartridge, as I'm still wary of using powders like this when I care about accuracy. It won't matter for guys who are fine with 1/2 MOA, or shooting bolt guns where rounds don't sit in a hot chamber for long, but I'm aiming for better. I don't like first-round flyers. As long as it's reasonable enough to be fine for non-target re: temp sensitivity (hunting, for example) then that'll be ok, as noted above I can compensate for temperature with a ballistic solver. I do have concerns about seasonal variation, I don't want to be leaving 75fps on the table between summer and winter, but we'll see.

Depending on the load, you certainly might leave 75 fps on the table between summer and winter (but some loads may not, ymmv). The alternative is mostly to leave 150+ fps on the table all the time, and still deal with some variation, so it depends on your needs which one is better. I may be exaggerating a little, but the idea is solid. Even cold temp Lever speeds are still faster than what the stick powders can do with good brass life in my experience, although ymmv again.

Also, I'm finding lately that temp sensitivity of Lever is not linear. My latest testing in my 12.5" with the 105 BTHP shows a pretty linear drop between 75°F and 40°F, but no drop at all between 40°F and -5°F and actually a slight increase. Not what I expected. I also did not see much change between 70°F and 95°F this summer. I don't shoot when it's hotter than that so you'll have to get higher temp data from someone else.

 

[ormandj]

Depending on the load, you certainly might leave 75 fps on the table between summer and winter (but some loads may not, ymmv). The alternative is mostly to leave 150+ fps on the table all the time, and still deal with some variation, so it depends on your needs which one is better. I may be exaggerating a little, but the idea is solid. Even cold temp Lever speeds are still faster than what the stick powders can do with good brass life in my experience, although ymmv again.

Also, I'm finding lately that temp sensitivity of Lever is not linear. My latest testing in my 12.5" with the 105 BTHP shows a pretty linear drop between 75°F and 40°F, but no drop at all between 40°F and -5°F and actually a slight increase. Not what I expected. I also did not see much change between 70°F and 95°F this summer. I don't shoot when it's hotter than that so you'll have to get higher temp data from someone else.

Hah, I'm with you, it's why I'm giving it a shot. I just bought some LVR to compare with CFE223. I can always do summer/winter loads if the difference is significant. Your report of 70-95 is great news though, that's a typical swing of temperature for me during the morning to day in the San Antonio area. How many FPS difference were you seeing with a swing that wide?

 

[Yondering]

Hah, I'm with you, it's why I'm giving it a shot. I just bought some LVR to compare with CFE223. I can always do summer/winter loads if the difference is significant. Your report of 70-95 is great news though, that's a typical swing of temperature for me during the morning to day in the San Antonio area. How many FPS difference were you seeing with a swing that wide?

I didn't list a number on the 70-95° variation because it was within the normal shot to shot deviation and I didn't fire enough rounds over the chrono to nail it down (I mostly shoot across a canyon, and don't sit back far enough for a chrono there). That particular load is really consistent though, so I'm guessing 5-8 fps variation at the most? But could be a lot less, I can't give a solid number.

I can say that the 0°F temp readings were 6 fps faster than the 40° readings. That surprised me.
For that test, I left the rifle and ammo outside for a few hours at 40° and tested, then put it in the freezer for a while and tested again (it takes about 30 seconds to yank it out of the freezer and walk in the yard to shoot). I did learn a lesson on cold-weather lube though; the firing pin was stiff enough with lube and fouling that it wouldn't fire when frozen. I dropped in a different bcg and it ran fine though. I think I'll be testing again with a clean unlubed firing pin.

 

[ormandj]

I didn't list a number on the 70-95° variation because it was within the normal shot to shot deviation and I didn't fire enough rounds over the chrono to nail it down (I mostly shoot across a canyon, and don't sit back far enough for a chrono there). That particular load is really consistent though, so I'm guessing 5-8 fps variation at the most? But could be a lot less, I can't give a solid number.

I can say that the 0°F temp readings were 6 fps faster than the 40° readings. That surprised me.
For that test, I left the rifle and ammo outside for a few hours at 40° and tested, then put it in the freezer for a while and tested again (it takes about 30 seconds to yank it out of the freezer and walk in the yard to shoot). I did learn a lesson on cold-weather lube though; the firing pin was stiff enough with lube and fouling that it wouldn't fire when frozen. I dropped in a different bcg and it ran fine though. I think I'll be testing again with a clean unlubed firing pin.

Wow. Well, 8lbs of LVR incoming. If the variation was in the noise, that's excellent for that temperature range, which is the one I'm primarily concerned about (70-100F or so, realistically). It sounds like LVR is proving to be a lot more temperature stable than CFE223 in 'real' temperatures with this cartridge. Is that what people have found, or is it just me reading into something that isn't there?

Thanks for all the info!

 

[Yondering]

Is that what people have found, or is it just me reading into something that isn't there?

I'm also interested to hear if other people here have measured the temp stability of Lever, and what the results were (and in what cartridge and load).

I get the impression that most people don't actually test this, but just try to calculate by some estimated value, which obviously doesn't work with non-linear changes.

Case in point - that data I mentioned above is showing Lever temp sensitivity at 2.3 fps/°F between 40° and 75°, but nearly 0 fps/°F above and below that.
If you average the 0°F and 75°f points though it's 1 fps/°F. If you average between 0°F and 95°f it's about 0.78 fps/°F. Neither of those are accurate enough to be worth using though.

 

[ormandj]

FWIW, I just went to buy some more LVR for testing and noticed it's becoming harder to find online. Hornady had warned me that they expected it to start selling quickly after release of the 6mm ARC, so perhaps that's happening now. I've _never_ seen LVR out of stock anywhere prior to this. My local stores don't even stock it since it wasn't a commonly used powder. It's unfortunate, because between primers, powders, brass, and projectiles it's becoming hard for anybody new to reloading who hasn't stocked up yet to even get started. There's still a few smaller places with LVR available, but the big players have all gone out of stock.

 

[Dino11]

Monday I picked up the last 8# jug that my local reloading supply place had, they still had several 1# left.

After I left there I stopped and met a guy selling a really nice front rest and traded him a 8# jug of IMR 4350 for it. We met at another gun shop and afterwards we went inside and he talked me into trying BLC-2. So I picked up an 8# jug of that to try.

BLC-2 falls between CFE223 and Lever, so I looked up 6mm PPC load data and used it for a base line to load 6 ARC.

6mm PPC has a case capacity of 33 gr of water and the 6mm ARC has a capacity of 34 gr of water.
So I started at 26.7 and worked in .3 gr increments till I got to 27.9 gr and stopped their. Velocity was still not were it needed to be. Using Nosler 105 RDF's I was only getting 2450 from 27.9 gr but no signs of pressure, so I am going to pick up were I left off and continue up to 29.5 gr next time out. I was actually surprised at the accuracy of these rounds considering the low velocity, and the SD's were getting into the single digits and getting better with each load work up.

BLC-2 looks like it might make my list of powders to use for this platform. And I love Lever it has been my go to after trying three or four different powders and different bullets.

 

[newageroman]

Sounds like I'm in the right place here. Lots of similar questions/loads.

I created a new brass trading site brassbucket.net. All free for now with advanced search options. Keep in mind its a work in progress. If there are some advanced brass options I'm missing, please let me know. I'm about to add more calibers and annealing options.

Having said that, here is some of my most recent results - all with reformed Starline brass, CCI 400 primers, berger 105s HTs seated to 2.230" out of 20" CMMG barrel:

• Shot 8 round groups of ppVarmit - meh group of ~1MOA - I'm still getting used to rifle, could have been a tad better shooting on my part
• Leverloution Ladder loads - pairs loaded in .5 increments from 25.0 - 28.5 grains - saw slight swipes at 28.5 so stopped there. No chrono data (I forgot my Tripod head and left it on the camera at home)
• I have the SA adj gas block and just left it at same setting that was used for the 224 wyle build. I may start tweaking it a bit more as described above (used that same process when I set it up for the 224 wylde). If I end up closing the gas block a bit more, would that not equate to a bit more velocity or no?
• I just added a nice seekins precision 30 cal muzzle brake and wow what a difference! Before I was just running it bare threads and was not impressed with how soft it shot. I was having trouble spotting shots at 5/600 even 7x power. Now it just sits there ready for the next in line.
• I also added a bipod that attaches to the sides of the handguard and that also helped quite a bit. These 2 upgrades really did seem to help more than I had expected.
• I'm getting some weird cratering on the primers even at moderate loads. It may be something on the bolt face or primer pin protrusion. I took a loupe and looked and it seems that the very center of the crater has a tiny nipple at the very center/bottom - almost like its about to be pierced. I DID have 1 peirced primer when I tried first Hornady ladder loads. The primers look the same as the other rounds in that group that did not pierce.
• comparing my brass to the hornady range scrap I used, the H brass is has noticeable ejector marks and much flatter primers compared to the same loads in Starline Brass - BUT, I don't remember if the H brass had any ejector marks previously. Still, the primers alone tell me the Starline is better in that respect.
• I'm glad to hear that neck turning is a waste of time in gas guns. I was wondering if converting the grendle brass to ARC would make the necks a tad thicker and having no way to turn down, is this increasing neck tension to an amount that would increase pressure sign or not.
• My loading plan going forward is to make some more ppVarmit rounds, try to take them to 750 or mayyyybe more. I will also load some LeverLoution in .3 grain increments around my max ladder load and try them out too. I will take the chrono this time for sure!

Thanks for all the info and looking forward to more.

 

[ormandj]

Neck turning isn’t a waste in gas guns. It just may not be worth the time to some people, and definitely isn’t worth it if you don’t have the right equipment for it to matter. Based on the uniformity (or lack thereof) the Hornady brass I’ve encountered so far, it’s worth it to me to get more consistent neck tension. I haven’t tested enough to know if it will make a difference on paper since I just turned all my brass upfront and won’t need to do it again.

If you’re sizing down existing brass, it might be worth checking what your neck thickness variation is. If it’s small, then expanding it with a mandrel should lead to relatively consistent neck tension, but if you’re seeing large variances it might be notable on paper. What barrel are you using? What is your expectation in group size? I wouldn’t just write it off, but I also wouldn’t turn on every firing. For me it’s a one time operation for gas gun cases until I wear them out, unless my groups start to grow at which point I’ll check again.

Does 1/10th an inch matter to you? That’s the order of magnitude we are talking about here, so if not, skip it!

 

[Henryrifle]

Curious if any of you have experimented with the 107 grain Sierra MatchKing for the 6mm ARC or one of the other similar cartridges? I ask because those bullets seem widely available, very reasonably priced and appear to have the seating depth insensitivity of a tangent or hybrid ogive.

Henryrifle

 

[Dino11]

Curious if any of you have experimented with the 107 grain Sierra MatchKing for the 6mm ARC or one of the other similar cartridges? I ask because those bullets seem widely available, very reasonably priced and appear to have the seating depth insensitivity of a tangent or hybrid ogive.

Henryrifle

I don't use the Match Kings but do use the Nosler 105 gr RDF's. Similar bullet and I pretty much use them exclusivly, they shoot way better than the Hornady 105's and their 108 offerings. I get the Noslers when they are on sale for about .26 each, and have paid as little as .20 each. They are very accurate and shoot very well at distance out to 800 yards, that's as far as I have shot them to date. Just had another 500 dropped off today.

Hornady on left Nosler on the right

 

[newageroman]

I went back last night and cleaned the bolt an got rid of some brass trimmings that ws causing the funky stuff around the primer impact. Also confirmed primer protrusion GTG.
I might try turning it just seems like a $$$hole for me. I could live without the las 1/10th of accuracy left on turning, at least for now.
I do like the idea of Manderal die however.

 

[Henryrifle]

@Dino11: Thanks for your thoughts. I actually have a box of RDFs to try but searching around reveals that RDFs are not in stock at the top level internet resellers I normally frequent. I'll play with the ones I have and see what I can get them to do.

Thanks again,
Henryrifle

 

[Yondering]

Sounds like I'm in the right place here. Lots of similar questions/loads.

....

Your primer issues are because you're using CCI400. Step up to the CCI450 (good luck finding them now though) and those issues will most likely go away.

Your Leverevolution load was not at max. Your swipes are from the rifle being overgassed; no reason to expect a gas block setting from a different rifle to be correct. Lever produces a lot of gas and if a rifle is tuned right for the common appropriate stick powders, a full charge of Lever will usually make it overgassed. Get that gas system tuned right so the swipes go away, and you can push the velocity a bit higher with Lever than anything else.

Starline and Lapua brass are both significantly better than Hornady.

Neck turning is definitely not a waste of time in ARs, especially if you're necking down brass.

 

[newageroman]

aww man. that all sounds pretty good advise, thx will post results.
I think that does answer a question I have, or bring it up for discussion anyway.

If it is overgassed, and I adjust as to vent more of the gas out of the block, would that not take away from the gas that pushes the bullet out of the barrel from the gas block to the end of the barrel? Perhaps I could MAKE UP for that vented gas, by increasing the powder charge overall?

Also the SA block is able to vent gas forward of the block to free air OR direct it down the tube to the bolt. Which one is most advantageous for my setup (Muzzle break/no supressor) - looking for higher velocities with some value toward follow up shots and reliability/functionality.

It seems like the following are true, please schl newb as needed or point me to other threads that may explain in detail:

• The best velocity would be fully closed gas block, sending all the power directly to the bullet - This would be overgassed and beat on the action/brass and would not provide "ideal" recoil impulse for follow ups.
• The softest shooting recoil impulse would be venting just enough gas to run the bolt, but that vented gas would lower vel.
• The best reliability would be to adjust a tad more gas than holds for last round hold open(as they describe in instructions/setup), but that would not be ideal for velocity OR follow up shots/soft shooting
• The ideal Gas Block setting is some magical number in the middle.

 

[MichiganMitten]

Starline and Lapua brass are both significantly better than Hornady.

Do you happen to have a link to the proper brass for 6mm ARC? I'm new to reloading, so I want to start out right.

 

[Dino11]

Do you happen to have a link to the proper brass for 6mm ARC? I'm new to reloading, so I want to start out right.

Hornady is the only game in town unless you want to resize and fire form Grendel brass.

And the stuff is out of stock just about every where. You could buy ammo, shoot it, and reclaim your brass to reload. This is what I have done. By the time you buy Hornady brass, process it, load it, you have the same money into it. So just buy ammo and shoot it.

 

[ormandj]

Do you happen to have a link to the proper brass for 6mm ARC? I'm new to reloading, so I want to start out right.

@Dino11 is spot on:

Hornady is the only game in town unless you want to resize and fire form Grendel brass.

And the stuff is out of stock just about every where. You could buy ammo, shoot it, and reclaim your brass to reload. This is what I have done. By the time you buy Hornady brass, process it, load it, you have the same money into it. So just buy ammo and shoot it.

Do exactly what he suggests. You’ll start with fire formed brass from your chamber and can work on your process from there. Don’t worry about the “perfect” process until you’ve got some more repetitions under your belt. As long as you practice good reloading fundamentals (buy a book or find a local who shoots 1/2 MOA or better with their reloads), stick to recipes from a good load data book (Hornady’s free data at this point), and start low and work your way up, you’ll have great shooting cartridges.

The nuances of brass quality and so forth show themselves in incrementally smaller ways, from number of times you can reload before primer pockets loosen to weight and neck thickness consistency. This stuff will matter when you’re chasing that last tenth, but overly complicated the process when just learning.

 

[newageroman]

Don't Do that ^^^ - I have processed and will be processing more Starline 6ARC brass for some of us that may need it. About to order more should be ready in a couple weeks.
Edit - I just ordered 500 cases, My first order of 250 cases took about a week and a half to get in. Stay tuned.

 

[ormandj]

Don't Do that ^^^ - I have processed and will be processing more Starline 6ARC brass for some of us that may need it. About to order more should be ready in a couple weeks.
Edit - I just ordered 500 cases, My first order of 250 cases took about a week and a half to get in. Stay tuned.

250 cases is a month or two of shooting (assuming 10x re-use) for one active person; you're going to supply the entire hide's worth of 6mm ARC shooters and be price competitive? You're necking down 6.5 Grendel Starline? You better have some automated case processing system, there's now way the math works out if you're doing it by hand. I can buy loaded 108gr eld-m match ammo that shoots quite well for about $1.30 a round with the current elevated prices. How much are you going to have to charge for your brass to turn a profit after operating expense? If it lasts an extra firing or two over the Hornady, it'd have to be in the same ballpark cost, factoring in the value added by the bullet/powder/primer in the factory ammunition. Hornady brass is going for a little over $0.60 each factory new right now.