7mm BR Remington

[comdiver]

Could a ar15 be made in 7mm be Remington. Not too long but got some power and accuracy.

[bstone5]

I made a 7mm BR bolt action on 788 Remington action the rifle shoots well.
i put the rifle for one of my sons some years back when he was 12 years old, he close to 40 years old now. The bolt face requirement may be too large a diameter for a A R 15.

[Doc Highwall]

The 7mmBr has the same bolt face as a 308 Winchester .473" way to big for a AR15 bolt, would fit a AR10 but now with the short case there could be feeding problems.

[joesig]

Looks like yes but... is that the easiest way to do what you want? Do you have an excess of 7MM BR brass to use or just want a 7MM with some thump? I like the cartridge in rifle or pistol but the AR platform can't be the best use for that case. You'll have to hunt for a bolt and I can't speak directly to the stacking of the case in a magazine.

Maybe a short 7MM TCU? Or is your heart set on a .473 case head?

[jmorris]

Using a 458 socom bolt would get you the right bolt face, as it uses .308 case head.

It would be a single stack round in a 223 mag as is the 458 socom, 450 BM and 50 beo.

[reed1911]

It certainly could be done, however I would highly suggest using an AR-10 for the platform. If you attempt to run the 7mmBR at full load it will quickly disassemble your AR15 for you. If you are just hankering for an AR-15 in 7mm, I would opt for the 7mm TCU or 7mm/223 (only difference is the shoulder and 2-3g more powder).

[joesig]

If you attempt to run the 7mmBR at full load it will quickly disassemble your AR15 for you.
With the large selections of cartridges for the AR platform, up to the .50 Beowulf, I have to ask why you say that.

[Doc Highwall]

I have read where a AR had been converted to 22Br to get a greater case capacity over the 223 and after firing so many rounds that some of the lugs on the bolt had either cracked or broke off. The AR platform can take the pressures of a 5.56 NATO round no problem with the .378"/223 bolt face.

[reed1911]

Take a look at the pressure specs of those larger head rounds, you will find they are all very low compared to the 7mm BR. 35KPSI for the SOCOM and 38.5KPSI for the 450BM and .50 BEO.

You can certainly run the 7mmBR in a -15, so long as you keep the pressure down in the 38KPSI range, standard loads run in the 50KPSI.

Remember the issue here is thrust on the bolt more than anything else. The barrel would likely have no issue (although I have not ran the numbers to verify that) but the bolt cannot handle that much back thrust and continue to stay serviceable.

[jmorris]

My 30 seconds of google for the day.

http://bulletin.accurateshooter.com/2009/04/brat-offers-6br-and-brx-uppers-for-ar-high-power-shooters/


do not merely use a .223-sized bolt opened up to fit the .308-sized rim of the 6BR case. Instead B.R.A.T. employs a different bolt design that is bigger, and significantly stronger in the lug area.