AR15 in 6mm BRX

sititunga

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Apr 20, 2009
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Anyone own one or used an AR15 in 6mm BRX?

BRX.jpg


Cartridge line-up left to right:

223, 6.5 Grendel, 6mm AR, 6mm WOA, 6mm BR, 6mm BRX, 6.5x47, 260 Rem

223 - Water capacity 30 gr
6.5 Grendel - Water capacity 35 gr
6mm/6.8 SPC/WOA - Water capacity 33.5 - 34 gr
6mmAR - Water Capacity 36 gr
6mm AR Turbo - Water Capacity 37 gr
6mmAR Turbo 40 deg IMP - Water Capacity 37.5 - 38 gr
6mm HAGAR - Water Capacity 37.5 - 38 gr
6mmBR - Water capacity 38 gr
<span style="text-decoration: underline"><span style="font-weight: bold">6mmBRX - Water capacity 43 gr</span></span>
6.5x47 - Water capacity 47 gr
260 Rem - Water capacity 53 gr

 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sititunga1</div><div class="ubbcode-body">Anyone own one or used an AR15 in 6mm BRX? </div></div>
Check out this data page on 6mmBR.com
6BR improved data page
 
Re: AR15 in 6mm BRX

Robert Whitley builds very accurate and reliable rigs, his 6mm Turbo 40 Improved is very impressive, however it doesn't have the same case capacity as the BRX (38 grains of water vs. 43 grains for the BRX).
 
Re: AR15 in 6mm BRX

There are two companies making 6mm BRX AR15 uppers at the moment - BR Armaments Technologies and AR15 Performance. Both are built differently. BRAT uses Oly's oversized WSSM bolts/carriers and barrel extensions and have developed their own mags in conjunction with C-Products. Their uppers are built primarily for the highpower crowd. AR15 Performance have gone a different route - they make their own custom bolts and barrel extensions and use 6.8 SPC mags. The mags they favor are Gen 1 PRI mags, however they say most other 6.8 SPC mags will also work.

There are pros and cons to both systems - some argue there is too much flex in the BRAT/Oly system to deliver consistent accuracy due to the thinner receiver wall around the oversized extension. Where as others are concerned about mag reliabilty with the other system.

The BRX shoots ubber flat - some velocity reports show it can deliver near 243 speeds. I think we might see more makers jumping on board.
 
Re: AR15 in 6mm BRX

The 6BRX has a .473 bolt face: same as 308WIN family. I question whether a small AR-15 chassis is appropriate for this type of cartridge. The construction of the upper does not lend itself to full-sized cartridges, heavier barrels, etc. There is a reason the AR10 platform exists and I think this cartridge is better suited for the larger platform. Just my .02
 
Re: AR15 in 6mm BRX

I think it all comes down to what you want to do with the rifle. If you want to shoot across the course matches the 6mmAR is probably the way to go. With today's billet upper and lower assemblies the 6mm rounds do just fine.

I know some gunsmiths won't touch a 6BR AR15 due to the small amount of barrel around the chamber. It's not for everybody. It does take care in reloading.

I have a 6mmAR turbo AND a 6br built by Gary Elesio. They both shoot the same out to 600 yards. They both shoot very, very well. My BR has more maintenance involved, including rebating the rims of the brass.

The turbo is turn-key and capable of winning the national matches if the shooter can. As far as varmint shooting is concerned I don't think a person needs to use a BRX to blowup a critter, other cartridges work just as well. There is more involved with a BR or BRX with either the BRAT or ARComp. builds, the mags will always be the weak link.
 
Re: AR15 in 6mm BRX

The 6 BRX does not need the rims rebated.
As far as loading take a case, CCI450 primer, 34.8gr of N550 and seat a 107SMk to 2.295 and shoot at 3090fps from a 26" barrel, not much extra work involved after fireforming but then the 6Turbo has to be fireformed too.
Watch the mil high-power "match rifle" shooters next year to see what they are shooting. We shipped 4 today and another 4 will go out next week.
 
Re: AR15 in 6mm BRX

I know the newer BR setups don't require rebating rims. Mine is an older setup from Gary, before he made the R5 stocks. With rebating a person can use a regular Colt 7.62x39 bolt.

The mags are still the issue. The AMU has a little bit more time and money than most to work out the bugs.

Yes, we will see how they do next year. They didn't run them this year??
 
Re: AR15 in 6mm BRX

I didn't finish the bolts until spring, sold the whole first batch of 50 bolt/extension sets because I didn't have time to build barrels at that point.
I then made a second batch of bolts and extensions, had several request for barrels and uppers so we started turning those out about 2 months ago. The guys I talked to wanted to finish the year with what they had been shooting, others were moving from "service rifle" to "match"

As far as mags PRI has them in stock or I send one out with every complete upper and they feed better than the Grendels I have had so I don't see a mag issue at all, BR dies are available anywhere.
I think we are going to do a rapid fire video next week.
 
Re: AR15 in 6mm BRX

this all comes down to what the original poster wants to do? he didn't answer.

NRA rules only permit certain mags. My Grendel mags won't even take five BR rounds in them. You are probably using 20 or 30 rounders and that's fine for you, but not everybody. 7.62x39 mags can fit 5 rounds but the mag won't fit into the mag well. Even running three at time, they didn't feed well. That doesn't sound like a workable solution for a NRA shooter. I'm guessing he is not a NRA shooter so using PRI mags will probably work for him.

I believe the owners of BRAT designed mags that work and they are not available from anywhere else but through them, as it should be, he designed them. His are designed for NRA comps.

Once again it all comes down to what you want to do and not the round. A local AMU reservist by me used a .223 matchrifle at the Nat's this year and did very well, even with one of his bullets blowing up in flight. The AMU fields great shooters, with any caliber.

It's the Indian, not the arrow that matters.
 
Re: AR15 in 6mm BRX

forgot to add. My mags from Gary, work. They are not a double stack configuration and that seems to be the only thing that will feed a BR in a AR, with a short mag.
 
Re: AR15 in 6mm BRX

11 BR cartridges fit in a 15 round mag.
Sounds like some new things have come along since you played with a BR in a AR.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Scooter-PIE</div><div class="ubbcode-body">The 6BRX has a .473 bolt face: same as 308WIN family. I question whether a small AR-15 chassis is appropriate for this type of cartridge. The construction of the upper does not lend itself to full-sized cartridges, heavier barrels, etc. There is a reason the AR10 platform exists and I think this cartridge is better suited for the larger platform. Just my .02 </div></div>

Agreed, but the AR10 is just that much bigger. Remember there are a few people out there shooting WSSMs out of their AR15s.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Xcount</div><div class="ubbcode-body">this all comes down to what the original poster wants to do? he didn't answer. </div></div>

I'm looking for an AR15 that will push me out to 1k for precision/tactical rifle matches. I don't want to use an AR10 or a bolt gun.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">I think we are going to do a rapid fire video next week. </div></div>

Good plan, I think we also need to see its accuracy potential - some pictures of groups would be great.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Xcount</div><div class="ubbcode-body">I know some gunsmiths won't touch a 6BR AR15 due to the small amount of barrel around the chamber. It's not for everybody. It does take care in reloading.

I have a 6mmAR turbo AND a 6br built by Gary Elesio. They both shoot the same out to 600 yards. They both shoot very, very well.</div></div>

AR15 Performance make their own barrel extensions which are standard size (same as a 556), where as those building this cartridge on the Oly system use oversized Oly extensions which means the receiver is thinner in the barrel join area. Some believe the Oly system compromises the rigidity and strength of the upper which wouldn't be good for consistent accuracy.

Have you taken your 6mm AR Turbo 40 out past 600 yds?
 
Re: AR15 in 6mm BRX

that's my point. Can't use any mag longer than a 10 rounder. I shot my Br just last weekend.

The OP pointed out his intentions so he's fine with longer mags. I'm just saying the 6BR is not plug and play for NRA shooters. The 6 turbo is a complete setup from one guy. I've heard about the Oly upper parts and I suppose there might be some truth to the thin wall upper. I don't have one so I can't comment. Just commenting on what I have and what I see at matches.

I've not shot my 6mm's past 600. They will give up velocity to bolt guns and I suppose accuracy would fall behind too. I know the owner of BRAT rifles is highly involved in HP and i'm sure tested them out to 1000. He would have specifics regarding LR.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Xcount</div><div class="ubbcode-body">I'm just saying the 6BR is not plug and play for NRA shooters. The 6 turbo is a complete setup from one guy. I've heard about the Oly upper parts and I suppose there might be some truth to the thin wall upper. I don't have one so I can't comment. Just commenting on what I have and what I see at matches.</div></div>

I think both options offer plug and play, it's just there are pros and cons to both systems. Dies are available for the BRX so reloading shouldn't be a problem - no more than the 6mm AR
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sititunga1</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">I think we are going to do a rapid fire video next week. </div></div>

Good plan, I think we also need to see its accuracy potential - some pictures of groups would be great. </div></div>
They will shoot 1/4 MOA off the bench with the right driver, with a shorter barrel it takes a hard hold. Driving with the left hand under the stock does not work as well as controlling the front.
N550, N540 and Re 17 give the best velocities but anything from Varget or RE15 up to 17 works with 105s or 7s.
PRI 10 round mags will probably hold 7.

Xcount, the rules state a 10 round mag as long as the dimensions do not exceed that of an issued 20 round mag. A 15 round mag is not near the length of a 20 round 5.56 mag.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sititunga1</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">I think we are going to do a rapid fire video next week. </div></div>

Good plan, I think we also need to see its accuracy potential - some pictures of groups would be great. </div></div>
They will shoot 1/4 MOA off the bench with the right driver, with a shorter barrel it takes a hard hold. Driving with the left hand under the stock does not work as well as controlling the front.
N550, N540 and Re 17 give the best velocities but anything from Varget or RE15 up to 17 works with 105s or 7s. </div></div>

Just how much bounce do you get from a BRX chambered AR with a 20-22 inch barrel off a bipod? How does the recoil compare to a WSSM? Would a longer heavier contour barrel be best for precision/tactical shooting?
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sititunga1</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sititunga1</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">I think we are going to do a rapid fire video next week. </div></div>

Good plan, I think we also need to see its accuracy potential - some pictures of groups would be great. </div></div>
They will shoot 1/4 MOA off the bench with the right driver, with a shorter barrel it takes a hard hold. Driving with the left hand under the stock does not work as well as controlling the front.
N550, N540 and Re 17 give the best velocities but anything from Varget or RE15 up to 17 works with 105s or 7s. </div></div>


Just how much bounce do you get from a BRX chambered AR with 20-22 inch barrel? How does the recoil compare to a WSSM? Would a longer heavier contour barrel be best for precision/tactical shooting? </div></div>

Not as much as a wssm for sure but more than a 5.56 or 6.8.
I shoot a 22" "precision" profile .950 under the guard, .875 gas block and .850 from the GB to the muzzle 12lbs with scope. The high-power crowd likes a .980, .936 gas block and .900 to a .750 muzzle 28-30"
A Hbar contour 20" is as light as I would go for any type of comp rifle.
As far as weight that depends on how much running you will do and how much you like to carry a 12lb rifle. I run a Mark IV because they are a lb lighter than a Nightforce or US Optics
 
Re: AR15 in 6mm BRX

Are any of you guys running a 243wssm? I'm just curious because I came across some Oly uppers while cruising around Midway's website and thought it might be something fun to have in an AR Platform.

I thought I read somewhere that the case water capacity was 56.5???? If so, sounds like something that would get the bullet cooking right along, and with the availability (I use that term loosely) of brass and ammunition from a major manufacturer it might make setting things up for reloading a bit easier???

I guess I'm just fishing for some pro's and con's of the 243wssm in comparison to a lot of the 6mm variants you have mentioned above.

lol...I'm already asking about 6mm odd-balls and just got ammo for my 6.5 Grendel.....Go figure.
smile.gif


Thanks,

-Pat

 
Re: AR15 in 6mm BRX

I've thought about getting into the 6mm's in an ar platform quite a bit, and every time I do, the .243 Winchester makes the most sense. I have cartridges that I have to load for and that is fine for what I want to do with those guns, but ultimately, the ability to go to a store and buy one of the 100's of factory loads for all different purposes pushes me in that direction for a semi-auto.

The BRX and the .243 have very similar performance, but 243 brass is cheap, 243 dies are cheap, and everybody and their mother has loads for it.

The AR Performance BRX stuff looks great and that is one hell of a cartridge, but really the gem on their site is the ITS-12. If it is stiff enough to maintain accuracy, shaving a couple of pounds off the AR-10 type rifles and using AR-15 handguards sounds like a great compromise for a .243.
 
Re: AR15 in 6mm BRX

The "12" with a 20" 6.5x47 fluted with a VTAC extreme rail on a DPMS 308 style lower is 8Lbs bare(no optic).
16" 308 is 7.5lbs
The highpower guys just don't like the AR10 platform, I don't see the difference between it and the 15 except the weight.
I really wish the 243 had a 30 degree shoulder, cheap, fast and accurate, after the 6x41 that will be my next wildcat.
edited to add quick function test video of ITS-12 in 308, this one is a 7.5 lb 308, 16" barrel with a MCD brake controlling the muzzle rise- vid
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body"> I think we are going to do a rapid fire video next week.</div></div>

Have you had a chance to shoot that video yet? And can you post some pictures of group sizes?
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body"> The "12" with a 20" 6.5x47 fluted with a VTAC extreme rail on a DPMS 308 style lower is 8Lbs bare(no optic).
16" 308 is 7.5lbs
The highpower guys just don't like the AR10 platform, I don't see the difference between it and the 15 except the weight.
<span style="font-weight: bold">I really wish the 243 had a 30 degree shoulder, cheap, fast and accurate, after the 6x41 that will be my next wildcat.</span></div></div>

Your wish has been granted:

243 with 30 degree shoulder
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigjohnintexas</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body"> The "12" with a 20" 6.5x47 fluted with a VTAC extreme rail on a DPMS 308 style lower is 8Lbs bare(no optic).
16" 308 is 7.5lbs
The highpower guys just don't like the AR10 platform, I don't see the difference between it and the 15 except the weight.
<span style="font-weight: bold">I really wish the 243 had a 30 degree shoulder, cheap, fast and accurate, after the 6x41 that will be my next wildcat.</span></div></div>

Your wish has been granted:

243 with 30 degree shoulder </div></div>
I have seen that, but wish the 243 had been originally created with a 30 degree.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sititunga1</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body"> I think we are going to do a rapid fire video next week.</div></div>

Have you had a chance to shoot that video yet? And can you post some pictures of group sizes? </div></div>
No, in the middle of machining 400 bolts.
 
Re: AR15 in 6mm BRX

So is Remingtons 30 RAR numbers a little over optimistic?

according to the numbers you can push a 125 grain 30 cal bullet only 100 fps slower than a 100 grain load in a 243 and the 30 Remington AR has 200 ft lbs more muzzle energy.

So I guess Im not understanding why you would want to go with a strange wild cat cartridge to get near 243 like performance out of an ar15 platform when you can go with the 30 Remington AR that already has similar velocity and a better ballistic co-efficient to the 243 plus those numbers could be improved with hand loading.

I only came across this information when I was comparing the 6.5 Grendel to the 243 and the 6.5 Grendel makes the 243 look like a monster then I found the numbers on the 30 rar.


 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mica</div><div class="ubbcode-body">So is Remingtons 30 RAR numbers a little over optimistic?

according to the numbers you can push a 125 grain 30 cal bullet only 100 fps slower than a 100 grain load in a 243 and the 30 Remington AR has 200 ft lbs more muzzle energy.

So I guess Im not understanding why you would want to go with a strange wild cat cartridge to get near 243 like performance out of an ar15 platform when you can go with the 30 Remington AR that already has similar velocity and a better ballistic co-efficient to the 243 plus those numbers could be improved with hand loading.

I only came across this information when I was comparing the 6.5 Grendel to the 243 and the 6.5 Grendel makes the 243 look like a monster then I found the numbers on the 30 rar.


</div></div>

The BC of the 6mm bullets the BRX pushes out are substantially higher than the BC of a 125gr flat based 30 cal bullet. The BRX is a 1000 yds cartridge, the 30 Rem AR is probably good to about 400.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mica</div><div class="ubbcode-body">So is Remingtons 30 RAR numbers a little over optimistic?

according to the numbers you can push a 125 grain 30 cal bullet only 100 fps slower than a 100 grain load in a 243 and the 30 Remington AR has 200 ft lbs more muzzle energy.

So I guess Im not understanding why you would want to go with a strange wild cat cartridge to get near 243 like performance out of an ar15 platform when you can go with the 30 Remington AR that already has similar velocity and a better ballistic co-efficient to the 243 plus those numbers could be improved with hand loading.

I only came across this information when I was comparing the 6.5 Grendel to the 243 and the 6.5 Grendel makes the 243 look like a monster then I found the numbers on the 30 rar.


</div></div>
The 30 RAR is a 300yd hunting round, the 6BRX a long distance comp round and only a strange wildcat to hunters, it has been around much longer than the 30RAR.
The 243 dia bullets have a much higer BC than the light 30 cal bullets 95SMK=BC .480, 107SMK=.518.
Here is the link to a thread where Bill Wilson tried to stir up some interest in the 30RAR
rar thread
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body"> I think we are going to do a rapid fire video next week.</div></div>

Have you had a chance to shoot that video yet? And can you post some pictures of group sizes?
 
Re: AR15 in 6mm BRX

All of them were AR15s except the 7mm-08 and that was a AR12.
Someone left the blue targets on the stand, I used them for the 6BRs since there weren't any holes. There are some other black targets(6BRX) on the forum somewhere, one marked 105 for 105 Amax and 1 Aston(customers name) I don't have time to shoot alot, usually 2 shots to get on paper then 5 for group and I move on to the next. I didn't work loads for the 2- 28" BRs, I dumped varget in the measure, threw a charge that measured 29.3 so I figured that was close enough, screwed the die down and seated a 95SMK, it hit 2.290 so I left it there loaded 40 and took off. The BRs and BRXs will shoot almost anything.
 
Re: AR15 in 6mm BRX

I think a well shot video of one of your 6mm BRX's in action is best way to generate wider interest in the potential of this cartridge and your rifles.
 
Re: AR15 in 6mm BRX

I'll get around to it when I have some free time, right now I am working 7 days a week building rifles and barely have time to get to the range ever 2 weeks.
 
Re: AR15 in 6mm BRX

6mmBRX in AR15-95gr SMK with a BC of .480 at 3180fps
I believe is about 100" flatter and has 20" less drift than a 308 shooting the 175 SMK at 1000yds.
This is not a BRAT or Oly system rifle.
function and mag test video
function video link
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">6mmBRX in AR15-95gr SMK with a BC of .480 at 3180fps
I believe is about 100" flatter and has 20" less drift than a 308 shooting the 175 SMK at 1000yds.
This is not a BRAT or Oly system rifle.
function and mag test video
function video link </div></div>

Harrison you're a complete star! Well done, this is what people need to see!
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sititunga1</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">6mmBRX in AR15-95gr SMK with a BC of .480 at 3180fps
I believe is about 100" flatter and has 20" less drift than a 308 shooting the 175 SMK at 1000yds.
This is not a BRAT or Oly system rifle.
function and mag test video
function video link </div></div>

Harrison you're a complete star! Well done, this is what people need to see! </div></div>
I am more of a behind the scenes kind of guy, we have a 6x41(SPC) for higher capacity shooting and a 30ARP(308 short close to a 30BRX but made with 308 surplus brass) for hunters coming too.
I have 2 6BRs going out to a shooter that usually finishes pretty high in the HP comps and have a few 6.5BRs to build for tactical shooters, just sent out a 264LBC lightweight 20" that shot a 5/16" group with factory Black Hills ammo so I was really happy with that coming from a lightweight barrel.
 
Re: AR15 in 6mm BRX

This is a quick function test of the ITS-12, it is between the Ar15 and AR10 in size and shoots 308 class cartridges, 6.5x47, 260, 7mm-08 etc, uses AR15 rails/handguards. This is a 16" 308 apx 7.5lbs before optics running a MCD (tunable brake) to control the muzzle movement- quick video
 
Re: AR15 in 6mm BRX

This has me reconsidering the .264 LBC-AR. With reasonable load development how high is the actual risk for breaking a bolt (there is apparently some controversy about the dangers of this happening.) I ask because the drop and windage are very appealing in the 6BRX.
 
Re: AR15 in 6mm BRX

Some good info in here. Looks like the 6BR has made a few changes since 2010 or my research was read wrong.

Looking at all of the wildcats, the 6BR(from ARP)seems to be the most user friendly to yeild the best results. I really don't want to get into fire forming or extra steps in the reloading process.

Its hard enough for me to find the time to reload 6.8 so if I can keep the same steps involved as the 6BR but get amazing long range target shooting perfromance, building a 6BR is where I need to go.
 
Re: AR15 in 6mm BRX

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">Back from the dead.</div></div>

The knack of bringing things back to life and into the light again is a specialty of mine it seems!
wink.gif