high performance AR-15 chamberings, the future?

S

steve garrett

Well-known member
I have followed the posts here about the many ar 15 wildcats. What I am not sure of is why some are not more popular than they are and the limitations of each. I know the 6x6.8 is popular around here and for good reason. however in order for me to go to the trouble I want something more. Why haven't the wildcats based on the BR case been more popular? Ar performance sells bolts and remington even did the 30 RAR. What about the WSSM uppers what is different about the uppers themselves from a standard upper. It seems like most guys are worried about trying to shoot the AR 15 a long ways, rather than simply shooting lighter bullets alot faster. To me I would think a new chambering that was suited to light bullets being pushed faster as well as being able to push heavies would be successful. IMO based on already having the 6.8 case and the grendel case, the one that makes the most since is something on a standard bolt face. IE BR, BRX, dasher, ETC. Anyways where do you think the future is. Are we going to see a new cartridge standardized with plug and play parts? What is your opinion of the perfect high performance AR chambering?
 
A .473 bolt face is hardly standard in an AR. ARP doesn't have a lock on those that fit in a standard extension. Everybody and their dog are making 9310 bolts now.

The WSSM and the 30 RAR are virtual proprietary deals. No brass is commonly available. The WSSM is too thick to massage. It's like working with heavy gauge drill pipe. Neither can be formed easily out of existing cases.

The BR is cool and workable but you really can't use the top pressure it is capable of. Lapua brass is good to work with. The case is about as big as you can stuff in one without a lot of effort. Running up to a 22 BRX would give you 22-250 speeds but the 22X6.8 is almost there now.

I don't see a lot of new ones on the horizon as we do have physical limitations of about 2.31 give or take and the vagaries of the gas system. The piston won't deliver accuracy and it appears that proprietary influence is hard at work there.

Just some thoughts from a guy that lives in a reloading room about eight hours a day and gives therapeutic massage to cartidge brass frequently.

Greg

PS: Grain for grain nothing outperforms a 6X6.8...nothing.
 
Originally Posted By: GLShooterA .473 bolt face is hardly standard in an AR. ARP doesn't have a lock on those that fit in a standard extension. Everybody and their dog are making 9310 bolts now.

The WSSM and the 30 RAR are virtual proprietary deals. No brass is commonly available. The WSSM is too thick to massage. It's like working with heavy gauge drill pipe. Neither can be formed easily out of existing cases.

The BR is cool and workable but you really can't use the top pressure it is capable of. Lapua brass is good to work with. The case is about as big as you can stuff in one without a lot of effort. Running up to a 22 BRX would give you 22-250 speeds but the 22X6.8 is almost there now.

I don't see a lot of new ones on the horizon as we do have physical limitations of about 2.31 give or take and the vagaries of the gas system. The piston won't deliver accuracy and it appears that proprietary influence is hard at work there.

Just some thoughts from a guy that lives in a reloading room about eight hours a day and gives therapeutic massage to cartidge brass frequently.

Greg

PS: Grain for grain nothing outperforms a 6X6.8...nothing.


Agreed...

Massage
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what I meant by standard was I guess standard in bolt gun bolt faces. GL you said you can't run the BR case at full pressures, why is that? With a case like the dasher or BRX how does the ar chamber do with fire forming? With an AR the brass needs to be FL sized.

I hear you on the 6.8 but its only running about 5 grains more horse power than a 223. the BR or BRX gets you double that maybe even more. what about the bolts and barrel extensions are those reliable for the .473 bolt face?
 
Originally Posted By: steve garrettwhat I meant by standard was I guess standard in bolt gun bolt faces. GL you said you can't run the BR case at full pressures, why is that? With a case like the dasher or BRX how does the ar chamber do with fire forming? With an AR the brass needs to be FL sized.

I hear you on the 6.8 but its only running about 5 grains more horse power than a 223. the BR or BRX gets you double that maybe even more. what about the bolts and barrel extensions are those reliable for the .473 bolt face?

Bolt thrust comes into play when you get up into the bigger case heads. It's hard on those lugs. The newer steels are cutting down on it somewhat and we are able to creep back up. Everything had better be square or you will see early failures. Not catastrophic just more parts rattling around in the extension than you should have.

Pressures can get pretty radical on the BR cases and many think that if the bolt gun will take it the AR will. High pressures, poorly balanced gas and various BCG weights/buffers all work against the self-feeder. Ejector swipes, extractor imprinting and ripped rims are common when the top end is reached. On a bolt gun you might see some ejector markings. With the proper lock up it is so much stronger and smaller dimensioned chambers compared to an AR. A usable case in the AR must be sized smaller just to be reliable. That extra few thousandths let things slam around a great deal more and this is problematic for the AR. That smallness shows up quick hn the base slams into the bolt face and flattens everything out with all the nice imperfections and tool marks showing up. It's a rocket on both ends.

Fire forming in the AR is like anything else. False shoulders and jammed bullets are the song of the day. The one issue is that the cases are not perfect as things are moving around during ejection and they will be a bit more variation than the bolt gun will show in case to case expansion measurements.

5 grains of powder is about 15% on a 223 vs. 6.8. Performance goes up greatly with that little extra propellant. Doubling the charge to the big boys is not a doubling in speed. Efficiency rules in the smaller guns and more bang per pound does come into play for many of us. Remember the rule of 4's and going bigger doesn't always work out. Those little guys can run at higher pressures and use the powder up though the quantity is limited a great deal and certain densities are not usable.

Bolts are much better for hanging onto their lugs and less breaking. The extensions are not any stronger. You can alter the bolt and make it a tad bigger for better distribution of rear thrust and make the extension accept that bolt but the extension thickens over the chamber remains the same. That's why they had to make the WSSM BE's much larger in extension and bolt.

The only 22-250 UMAR I have seen measurements on show a tad thicker bolt but there is some controversy over that. It appears the BE was opened up to allow the extra width in the lugs. As I said my numbers are anecdotal but for now most of us are stuck with a 1.000 BE.

The latest and greatest in the LWRC 6.8 was/is a laughable deal. They gained nothing in magazine length and the rifle is saddled with sole source parts for it. It is still running a 6.8 and regardless of the “improvements” offers nothing to Joe Shooter other than being Walter Mitty’ so you are using what a small contingent of people are using in sandy areas. On that note rumor has it that is going away too.

The way around this is a new sized rifle between the 15 and the 10 in all areas. This would give us more strength and longer COL. It is not going to happen in this market IMHO.

Just my thoughts and opinions. Like many things in the world YMMV and most certainly your ideas will.

Greg

 
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I have a friend with a new AR10, it supposedly has a new type of barrel in 308 that starts at a slow twist and then speeds it up as the bullet leaves the barrel.

I don't know how, or the specifics of it. But, so far at the range, it opperates really nicely and shoots great groups and has a vlave to deal with the suppressor when it's added.

It's really nice to shoot an AR 10 at 500yrds pinging 10" plate with a suppresor and no ear muffs.
 
Originally Posted By: steve garrettare the WSSM uppers totally different than standard?? does anyone have a side by side of the barrel extensions?

I've already told you they were. I bet if you Google it you can find a picture. The bolt is also huge. Same charge handle. Slick side no door. Extra meat st various points.

Greg
 
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Imo the future should be the new DPMS g2 308 sized guns. Looks like an ar15 bolt carrier with a 308 size bolt. I handled one at a gun store and they handle and weigh like a 15 but with 308 length mags. I've been waiting for them to release calibers other than 308, not sure what the hold up is. They need to make all the parts available also, I really think that would be a game-changer. Then all your "standard" .473 bolt face rounds would be a walk in the park.
 
Originally Posted By: 204 ARImo the future should be the new DPMS g2 308 sized guns. Looks like an ar15 bolt carrier with a 308 size bolt. I handled one at a gun store and they handle and weigh like a 15 but with 308 length mags. I've been waiting for them to release calibers other than 308, not sure what the hold up is. They need to make all the parts available also, I really think that would be a game-changer. Then all your "standard" .473 bolt face rounds would be a walk in the park.

I think the hold up is softening sales. No one AFAIK is making aftermarket barrels for them. ..yet.

Greg
 
Originally Posted By: kwg020GI Shooter said:
PS: Grain for grain nothing outperforms a 6X6.8...nothing.

Wouldn't the .243 do this?

kwg

In a word, no. Yes the 243 shoots faster. But it takes almost 50% more powder to do it, so grain for grain the 6x6.8 wins.
 
Originally Posted By: 204 ARSomething in the works we need to know about Greg? Hmmm?

With Ritch on the point and me as a wingman who knows what the future holds. Shakers and movers enabled by Verizon....

Greg
 
When you lighten up the barrels like dpms did I think you need an even more premium barrel to supply the desired accuracy. It's too bad ar 10 isn't really standardized
 
Originally Posted By: steve garrettWhen you lighten up the barrels like dpms did I think you need an even more premium barrel to supply the desired accuracy. It's too bad ar 10 isn't really standardized

Garbage is garbage. You need quality premium barrels no matter what the weight. Fat doesn't mean squat for accuracy. Consistency builds success not mass by itself.

Greg
 
Originally Posted By: steve garrettWhen you lighten up the barrels like dpms did I think you need an even more premium barrel to supply the desired accuracy.

So you think a heavier barrel will let you use a lesser grade barrel ? Why would anyone think that ?
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The bore is the same no matter how "fat" the barrel is...
 
Originally Posted By: GLShooter No one AFAIK is making aftermarket barrels for them. ..yet.

Greg

FWIW, that may be on the horizon with Adams Arms/Voodoo:

Adams Arms Small Frame 308 Uppers

Adams Arms is now making uppers and rifles that are compatible with the DPMS GEN II parts. I assume aftermarket barrels could be available in the near future as well, based on that.
 


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