jim in Anchorage
Member
- Joined
- Feb 28, 2009
- Messages
- 2,849
O.k. there are blow back 9mm. But when does the base exert pressure on the bolt? At the full 38,500 psi or at some point below peak pressure? Also a 9mm is a poor example in this argument. The ratio of case wall[which is doing the holding] to base is much higher in a 30-30 then a 9mm. The 40,000 psi is not a absolute figure; a short fat case will produce backtrust at a lower psi then a long thin one.Ruger pc9 & 40
keltec sub 2k
high point 995
beretta storm
9mm ar15's
and just about any other 9mm carbine you can think of
The shoulder and neck where left alone. Only the case body in the chamber had the taper eliminated. It was a 30 bullet in a 30 bore. This is the whole concept of improved cartridges, some times with the neck blown out.sounds like you're describing a fireform load with a grossly undersized bullet IE no pressure
I sense some skepticism here that brass can hold 40.000 psi. It is very important to remember we are dealing with SHEAR strength, not BURSTING strength.
Picture a 3 by 3 ft piece of cardboard fastened by the edges to a open frame. Try to put your fist though it. Easy. That is its bursting strength.
Now take the same piece of cardboard and try to pull it straight apart. Impossible. That is it's shear strength.