Im sure this has been beaten like a dead horse but im not finding the info I would like. I was looking into building a good medium-long range (600-1000yd) AR and was going to do a 6.5 grendel. Iwas also considering rebarreling my Savage 10 to 6.5 grendel to match. Then I started reading about the 6mmAR and have become very intrigued. Id love to have a matching set gas gun/ bolt gun in the 6mmAR. My question in, how does this cartridge compare to the 6BR in performance (velocity, accuracy) out of a 24-28" barrel. What is the case capacity difference between the 6mmAR and the 6BR. Does anyone have a side by side photo of the two cortidges? I have searched high and low and cannot find one. Thank you all in advance!
6MM AR vs 6 BR
- Thread starter mao0720
- Start date
I've used a 6mmRAT quite a bit. (very similar to the 6mmARTurbo40°) But no straight 6mmAR.
Check 6mmar.com for information on the 6mmAR family of cartridges.
The improved (turbo 40°, RAT) Grendel based cartridges are right up there with the 6BR. (more or less... 2900ish fps with a 105-class bullet) Some folks don't like using the PPC case head in an AR, on account of reduced metal around the bolt lugs. (But the newer, higher end bolts seem to have that well addressed, and the ones I've seen fail failed gracefully--no catastrophic damage, just failed to extract following the breakage. And all of those I've seen were with older bolts)
It's going to be tough to match what a good bolt gun can do with a 6BR with an AR15... but that said, my 6RAT was extremely accurate out to 600, which was the farthest I shot it--since that's the limit of the HP course of fire.
If you're looking for a 6BR's performance in an AR15, the improved Grendel cases are about as close as you're going to get. (Without going for one of the 6BR AR15s, which have a bit of a mixed reputation) The straight 6mmAR will be 100-200fps slower, but won't require fireforming. Although because you're necking down the cases, you can simply run the case in the sizing die, then load a slightly reduced charge as normal--so fireforming the improved cases is a pretty easy step.
Check 6mmar.com for information on the 6mmAR family of cartridges.
The improved (turbo 40°, RAT) Grendel based cartridges are right up there with the 6BR. (more or less... 2900ish fps with a 105-class bullet) Some folks don't like using the PPC case head in an AR, on account of reduced metal around the bolt lugs. (But the newer, higher end bolts seem to have that well addressed, and the ones I've seen fail failed gracefully--no catastrophic damage, just failed to extract following the breakage. And all of those I've seen were with older bolts)
It's going to be tough to match what a good bolt gun can do with a 6BR with an AR15... but that said, my 6RAT was extremely accurate out to 600, which was the farthest I shot it--since that's the limit of the HP course of fire.
If you're looking for a 6BR's performance in an AR15, the improved Grendel cases are about as close as you're going to get. (Without going for one of the 6BR AR15s, which have a bit of a mixed reputation) The straight 6mmAR will be 100-200fps slower, but won't require fireforming. Although because you're necking down the cases, you can simply run the case in the sizing die, then load a slightly reduced charge as normal--so fireforming the improved cases is a pretty easy step.
JohnW...ski
Gold $$ Contributor
I had a 24" heavy barrel AR built with a 1 in 8" twist. The rifle has been very accurate with 90 and 95 gr. bullets, I have had less luck with heavier bullets probably because I chose a shorter than 26" barrel. I am in the process of building a benchrest rifle using a BAT action and Bartlien 1 -8 barrel. The down side of this build is I had to have custom 6mm AR reamers made which was costly. I am curious to see weather the 6mm AR in a true bench rest rifle can really produce bench rest accuracy. There is no reason that it shouldn't, it is basically a blown out 6mm PPC which is probably the gold standard for accurate cartridges.
The case capacity of a 6mm AR is about 36 gr. of H2O, almost right inbetween a 6 mm PPC, around 32 gr. H2O, and a 6mm BR, around 39.0 gr. H2O.
6mm AR (L), 6mm BR (R)
Good luck,
John
The case capacity of a 6mm AR is about 36 gr. of H2O, almost right inbetween a 6 mm PPC, around 32 gr. H2O, and a 6mm BR, around 39.0 gr. H2O.
6mm AR (L), 6mm BR (R)
Good luck,
John
I have two 6AR uppers built by Robert Whitley. One is a button rifled Hart barrel, the other a canted land Bartlein. Both are 26" long with an 8 twist. Both uppers drive 90 gr. bullets at 2,825 fps. and the 105's at 2,750 fps. Either of them are capable of shooting a clean if I drive correctly. My shooting partner has a 6BR in a Savage bolt rifle and he is about 150-175 fps. faster across the board but also has a 30" barrel.
I hope this helps,
Lloyd
I hope this helps,
Lloyd
Thanks for all the info, and the photo! To be clear I am not trying to make an AR equivelent to a bolt gun. The Idea is to have an AR15 in 6mmAR as a match rifle and rebarrel my savge 10 in 6mmAR as a long range plinking/ varmint rifle. This is all the exact info I was looking for. Unfortunately, 6mmar.com doesnt have any info for the straight 6mmAR anymore, but you guys answered most of my question, thanks again!
I shoot 6mmAR in my across the course spacegun (built by Fred Sablewski and Robert Whitley)... I have found no need to go to the 6AR Turbo, or improved etc. etc. The straight 6AR shoots 1/2 minute consistently with the Hornady 87s for 200, the Berger 108s at mag length for 300 and the 105 hybrids at 600. The modified 6s are not worth the trouble for another 75fps for me.
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