I had a partial case head separation using a 1.8oz buffer

[Zeneffect]

I was thinking failure occurred after peak pressure regardless of the scenario, which is where barrel length would dictate available (diminishing) pressure before equalizing to atmosphere post projectile exit. Gas port is relatively small in comparison, like having a nail in your tire. Slow leak so there is some pressure drop but if I drill a 3" hole all of a sudden pressure drops much faster.