6BR 35k PSI Load

[S11033]

Hello,

I'm interested in exploring the use of a .458 bolt and barrel extension to build an AR15 in 6BR. This would obviously limit my max pressure to 35,000 PSI. I realize that 6mmAR would probably be a better option, but I already have 6BR brass and dies, and a barrel that I can have a bolt extension installed on.

The lowest pressure load that I've personally loaded for 6BR was a casefull of WC872 behind a Hornady 105gr HPBT, but I have no idea what the actual pressure of this load was. Does anybody with Quickload know if I could load something in the realm of 35k with WC872?

The next question I guess is whether it would even cycle...

Thank you!

Steve

 

[joshb]

Take a look at the 6x45. I have no experience with an auto loader but Mag feeding in a bolt gun can be tricky, sometimes with the short fat 6br case. Talk of “down loading” the 6 br pressures makes me mention the 6x45. Building an iffy project just to use your brass? Hmmmm! Might want to put some more thought into it.

Add: To address your boltface, look at the 30 Grendel. I think that’s what some guys are really liking for accuracy. Just by memory, which is iffy.

 

[shoot4fun]

It took a moment to figure out what you meant by .458 bolt. You mean using the .458 SOCCOM bolt which has a .473 bolt face don't you?
I also think you base your 35,000 PSI limit on the fact that is max SAAMI pressure for the .458 SOCCOM load. Correct?
If so, and strictly conjecture on my part, I would think the SOCCOM pressure limit comes from the fact the parent case is the 50AE pistol case and, as such, was designed around normal pistol cartridge pressure limits or "rules" if you will.
I would think, as the AR15 is generally capable of operating at much higher PSI than 35,000 (and 6 BR brass the same) that you would not be limited to your self-imposed 35,000 number. But I am not any kind of expert.
Now, maybe you are looking at the AR15 for its size/weight advantage? If so, I would say you should look at such a project on one of the new breed of GenII AR-10 platforms that advertise 308 power on a smaller scale size and lower weight for your project.
Also, this may be the best advise so far, get opinions from the guys who know the AR platform thru and thru. John-Paul at JP Enterprises comes to mind for one.

 

[10at6]

Do you have a bolt for the 15 in a 308 bolt face?

 

[rockhound78]

Also, take a look at the 6mm Grendel for your AR.

 

[shoot4fun]

Do you have a bolt for the 15 in a 308 bolt face?

He says using the .458 bolt. The .458 SOCCOM round uses a .473" bolt face.

 

[10at6]

Missed that...6 AR is a better choice.

 

[Liven The Dream]

Few years back this was tried ?
Not safe and trouble times 2 .
Barrel extension to thin .

 

[Ggmac]

It's usually best and less expensive to forget about building a gun especially modifying parts just because you have the brass and components. Go with the 6 TCU or similar .

 

[S11033]

Wow, I guess I had notifications turned off and missed these replies. Yes, I did mean a 458 SOCOM bolt with a .473 bolt face.

Fortunately, the 6 ARC has finally come along to give me exactly what I was looking for! I have 24" bull barrel and 12.5" mid-weight uppers.

Cheers,

Steve