6BR or BRX in a AR 15 platform

[yotehunter247]

I have been kicking around the idea of building a new coyote rig in an AR platform. I had my mind set on the 6mm spc but last night I found a guy in colorado that make a 6 BR in an ar15 platform. I know a few guys that are shooting the 6 spc with no problems. Im trying to find some one that is running a 6 Br in an AR platform I have heard talk of feeding issues is there anyone that can help me out.

 

[scout1]

Give Robert a call. Heres his website http://www.6mmar.com/

 

[Hapnin]

I am running a 6spc and have been happy with it so far (having some reloading problems right now). The 6br would be a great round in an AR I think but I have also heard/ read that the barrel extension has to be bored out so much as to be quite a bit on the thin side. I'm not trying to steer anyone one way or the other as I haven't researched it very much at all. That's just one thing that I have heard/ read about that chambering in the AR. Again I think that a 6br would be great if it can be done safely. I'd be interested in one as well. Good luck.

 

[Matt Pitchon]

BR Armament Technology makes an upper and mags that work. http://www.bratrifles.com/. Not cheap, but accurate and reliable. If you want to do it yourself, you can get a bolt and extension that fits in a standard upper, http://www.ar15performance.com/6mmbr___473__bolt. You will need to find a mag that works. The 6AR by Robert Whitley works, is accurate, and has almost as performance as the 6BR. White Oak also makes something called a 6RAT, which is a 6AR Turbo at a lower price. There are lots of options, its a matter of preference.

 

[yotehunter247]

I have been doing some serious research on the 6 spc. I have a buddy running 75 v-max at 3100 and another running 55 at 3450. I would like to run 65 to 75 around the 3300 to 3500 mark. I am also trying to stay away from having to fire form brass. I talked to the guy in CO at AR performance he said they have been having good luck with his stuff and running 6.8 spc mags for the 6 BR. He was also shooting the heavier bullets. I didn't ask him about feeding issues, but who knows. I figured I have until mid summer to figure out what I want to do. Thanks to all so far for the info.

Richard

 

[constructor]

My personal rig is 22", I have been shooting 95SMks from 3060 to 3200fps and 105 Amax about 3040. I use PRI 6.8 mags because I can load them to 2.3" and that is what works with the .100 leade on the 6mmBRX-AR reamer that Kiff made for me, it was the first one he had made specifically for the AR but we hit the leade perfect for the bullets I use, it's also a .272 no-turn neck . With Varmint bullets you may be able to load shorter and still be close to the lands then use 7.62x39 mags that allow 2.28 OAL.
I only load about 10 at a time in a mag so the 20 rounder works fine for that.
Temporarily sold out of bolts and extensions but, I'll make another run of a hundred or so in the next month. Bolts fit unmodified carriers and extensions fit unmodified receivers.

 

[Kenny474]

The 6br would be a great round in an AR I think but I have also heard/ read that the barrel extension has to be bored out so much as to be quite a bit on the thin side.

I would think if the .243 wssm can be chambered in an AR than the 6mmBR being .050" smaller in diameter shouldn't be a problem.

 

[joghotrod]

The guys building 6BR AR's are using bolts and barrel extensions made by Olympic arms for their WSSM rifles. They don't bore out the bolts as much for use in the 6MM AR's.

Jimmy

 

[rcw3]

The guys building 6BR AR's are using bolts and barrel extensions made by Olympic arms for their WSSM rifles. They don't bore out the bolts as much for use in the 6MM AR's.

Jimmy

Just a point of clarification here - we don't bore out bolts - our bolts are made with the proper bolt face from the get go.

Robert Whitley
www.6mmAR.com

 

[constructor]

The guys building 6BR AR's are using bolts and barrel extensions made by Olympic arms for their WSSM rifles. They don't bore out the bolts as much for use in the 6MM AR's.

Jimmy

SOME use Oly bolts, extensions and carriers with the receiver bored out to 1.050 to accept the larger extension. We don't, we don't use bored out AR15 bolts either. http://www.ar15performance.com/6mmbr___473__bolt

 

[rcw3]

For what it's worth I like some of the aspects of the set up Constructor (AR Performance) is offering, some well thought out parts for using a 6BR out of an AR-15. The Olympic type parts set up (after you open up the receiver to accept the barrel extension) leaves the metal on the front of the receiver very very thin which was never my preference for an accuracy build up (we like the heavy walled rigid upper receivers for accuracy build ups).

Honestly the magazines for the 6BR set ups out of AR-15's is still something that needs to be optimized - there are working magazines for sure but no one has really got it down 100% easy "plug and play" yet. The set up that uses the Olympic parts is a C-Products double stack but single feed right from the center of the magazine (over top of the bottom center lug in the extension). For a fat cartridge like a 6BR or BRX out of an AR-15, we like M-4 type feed ramping (like Constructor's set up), but when you have to feed over top of the bottom extension lug (like the Oly set up), that makes that an issue. Also unlike normal AR-15 magazines, with the Oly set up you cannot just snap the rounds down in the magazines and with the Oly set up and you have to load the rounds like you do with a Ruger 10/22 magazine (in from the front and back over top of the prior round), which is annoying if you need to do a lot of magazine feed sequences and loading. Constructor's set up uses either side M-4 feed ramps which I think is good (we use that set up with our 6mmAR and Turbo 40 cartridges and it works great) and he has been working with PRI 6.8 SPC magazines (Gen 1 - non waffle mags) for 10 round feeding sequences. With the 6BR uppers we built we were really looking for 5 rounds of reliable feeding and used the current production PRI 6.8 SPC magazines (Gen II waffle type) and some worked and fed great and some did not (although the ones that did not still worked great for either 6.8 SPC rounds, or for up to about 7 rounds of our 6mmAR and Turbo 40 rounds). What we did is buy a bunch of the PRI waffle 10 round magazines, those that fed the 6BR fine we used for the 6BR, those that did not we sold off for 6.8 SPC shooters or used them here and there for 6mmAR and Turbo 40 shooters that like the longer OAL that can be had from using the PRI mags. The PRI magazines allow you to just snap the rounds down into the magazine when loading, just like with normal AR-15 magazines.

6BRX is what I find really tempting to try since our Turbo 40 cartridge does all that a 6BR can do, and right now to do a BRX it seems you either have to run with the Oly set up with its pluses and minuses, or run with Constructor's set up and do a little to get a compliment of dialed in magazines, which is certainly possible (both he and I did it independent of each other with PRI magazines).

Robert Whitley
www.6mmAR.com

 

[Westex]

I built a 6mm 30AR on the AR15 platform . I used the AR 15 Performance bolt and barrel extension . I used a 8 twist Bartlien barrel 26" long . I plan on shooting some long range coyotes with it . I have only killed wild hogs with it so far and it really works great on them . I have not had a lot of time to work up a lot of different loads for it but it really shoots good with 107 smk's and 36.1 grains of H4350 powder . I have all kinds of 6mm bullets I want to try in it for varmint hunting . I will chrono the next time I go to the range . I really like the 30 caliber version for hog hunting I am getting 3100 plus fps with 110 grain Sr varmint bullets . I can use a modifide 30 round magpul clip and get about 13 rounds in it . The 6mm version if a different story with the long vld bullets like the 107 smk's . I can only get six in a modifide bushmaster 450 clip . I would like to try some 300 to 400 yard target shooting to see how it performs. Later ! Mark

 

[rcw3]

Mark/Westex

Just curious where you get Remington 30AR brass to make a 6mm out of it, since that is not really commercially available at present as far as I can tell (although maybe I am not up on that).

Robert Whitley

 

[Westex]

Hello Robert ! I had to buy loaded 30AR ammo from where ever I could find it for sale on the internet. I shoot a 30AR and used some of the once fired brass to form the 6mm 30AR . Thanks! Mark

 

[cruft]

stop and think some more. you're making this way too complicated. get a 6.5 Grendel. do you really believe that a bunch of guys on the forum have the brain power or resources to come up with a cobbled together platform? do you want to play around or hunt? let others experiment and develope. there are choices that will fill you desires with platforms already worked out.

 

[cruft]

of course that doesn't apply to Robert W... :-[

 

[Westex]

??? ???

 

[constructor]

??? ???

Don't pay any attention to guys that can do nothing but buy it off the shelf, let us know how she's working. velocities too.
I've been playing around with the 95 SMKs in a 6BRX, 33gr of RE15 averaged 3047 from a 22" barrel
first group was .4, top end was 3203 with N550.
Top end with the 107s was 3038 also with N550 but RE17 was right there with it.
Haven't had much time to develop loads but I wanted to find out what the max was.

 

[JerryMay]

Well said Constructor.... I if wasn't for people like Westex and Robert W we would all still be shooting .223 Remington! Keep the info coming Westex....how about some pictures of your Rifle, ammo, reloading, etc.
I've just finished building an AR15 in Roy Winnetts 22PDK... REALLY happy with the way it's performing so far, it beats my .223 easily by 250fps and bucks the wind better at 600 yards.
Jerry

 

[yotehunter247]

Well I got my upper in for the 6 BR coyote project gun. When constictor starts making the bolt faces and extionsions I'll pick that up. I have a Rock creek barrell already. and still need to pick up some of the smaller items. My gunsmith is really interested in this project also. He already has the 6 br reamerr and gauges since he is a benchrest shooter. Thanks to all for the input. I can't wait!!!