BRA Piston upper… Bolt carrier gets stuck in buffer to

[GBMaryland]

I was testing supersonic 147 grain loads today on a rifle with a BRA piston upper.

They’re not exactly hot and there’s no excessive pressure signs on the cases.

However did dawn on me that I had been using subsonic loads previously and exclusively.

I’m pretty sure the upper came with a buffer but I’m not so sure it came with a spring.

There is a hole in the bottom of the bolt carrier group and if the buffer goes back far enough it gets stuck on the buffer retaining plunger (whatever hell it’s actually called).

The spring that was in the buffer tube had a green end.

Anybody know what spring I should actually be using with this if I want to shoot supersonic loads?

(these loads are 147 grain military surplus bullets with 16 grains of H110 behind them.)

 

[GBMaryland]

Updated to reflect a couple of words that Siri obviously not wrong

 

[srt-4_uk]

Their website mentions use of an oversized carrier buffer prevents binding. I'd order one.

Black Rifle Arms Patented 5.56 Bolt Carrier Group Buffer, NiB Exo Coating with Carrier Buffer System, Enhanced Bolt Carrier, Modified BCG

Second option is removing the buffer tube retaining pin and spring. It isn't necessary for function, just convenience. Keep in mind the buffer will come out when you take apart the upper and lower.

 

[GBMaryland]

In very faint lettering on the website it indicates a rifle length buffer spring and buffer.

So it turns out that it’s supposed to use a rifle system…. Humph.

I swapped in a rifle buffer for the function test and it works just fine. Good that I have a whole boatload of parts from all the old A.R. 15 side I used to have.

 

[TonyTheTiger]

There is a hole in the bottom of the bolt carrier group and if the buffer goes back far enough it gets stuck on the buffer retaining plunger (whatever hell it’s actually called).

I'm baffled by this. Got any pictures?

 

[Paradox]

I was testing supersonic 147 grain loads today on a rifle with a BRA piston upper.

They’re not exactly hot and there’s no excessive pressure signs on the cases.

However did dawn on me that I had been using subsonic loads previously and exclusively.

I’m pretty sure the upper came with a buffer but I’m not so sure it came with a spring.

There is a hole in the bottom of the bolt carrier group and if the buffer goes back far enough it gets stuck on the buffer retaining plunger (whatever hell it’s actually called).

The spring that was in the buffer tube had a green end.

Anybody know what spring I should actually be using with this if I want to shoot supersonic loads?

(these loads are 147 grain military surplus bullets with 16 grains of H110 behind them.)

 

[Paradox]

How about something really off the wall?

 

[GBMaryland]

That may actually be better than the 300 win mag AR10s.

I doubt he 4570 probably wears out the throat as quickly as the semi automatic 300 win mag

 

[Paradox]

Just haven’t seen one in cal and was kinda cool