The meaning of "crush"

[2-Stroke Dirt Devil]

Bottom line is that the AI chamber is typically .004" shorter than the parent case, at the neck/shoulder junction. That's where we get the "crush" term...the new brass slightly crushing to fit the shorter AI chamber. This crush is what keeps the parent brass from being pushed forward while fire forming. The parent GO gauge becomes your NO-GO. Since we're dealing with two different shoulder

Bottom line is that the AI chamber is typically .004" shorter than the parent case, at the neck/shoulder junction. That's where we get the "crush" term...the new brass slightly crushing to fit the shorter AI chamber. This crush is what keeps the parent brass from being pushed forward while fire forming. The parent GO gauge becomes your NO-GO. Since we're dealing with two different shoulder angles, the standard datum on the shoulder is NOT being used. I fail to see how "as fired" pertains here.

It's an old thread but yes, it's still done this way.

angles, the standard datum on the shoulder is NOT being used. I fail to see how "as fired" pertains here.

It's an old thread but yes, it's still done this way.

So the crush is primarily a need only when fire forming? If I understand this correctly.

Once fire formed, resize for headspace at 1.5 to 2 thou as normal?

 

[2-Stroke Dirt Devil]

Once fireformed to the Ackley chamber you would size the case normally as fired in that chamber and not add anything extra. That is if I get what your asking. The reduced chamber length for the Ackley chamber is so you have some case crush to hold the brass tight against the bolt face on first firing. That’ll keep potential case head separation at bay.

Got it. Crush for fire forming makes perfect sense. That clears it up thanks.

Somehow got the idea that the crush was for each firing of the brass.

 

[2-Stroke Dirt Devil]

Yes, an old thread, but looking into possibly building BRA in the next couple of years.

 

[Alex Wheeler]

Is this still a current practice?
Would we be resizing our brass from "As Fired" to "As Fired +0.004" for HS?

For me it is. If you got a BRA barrel from me in 2017 it will headspace the same as one I cut for you today.

 

[2-Stroke Dirt Devil]

For me it is. If you got a BRA barrel from me in 2017 it will headspace the same as one I cut for you today.

I dare hope to one day own one of your builds.