Silversmok3
Member
We only know that SAAMI specs for 40SW is 35,000 psi. We know the manufacturer states the ammo tests out to 34,000 psi.
We don't really know what the gun is rated to. Only S&W design engineers know that information and I would think they would design spec it to something greater than the SAAMI specs for the round.
Lets go back to the facts we know.
Underwood calls this load " 40S&W +p". That's a standard which doesn't exist. +p typically means the round exceeds SAAMI spec.Very few companies design their guns to handle velocities past SAAMI standard.Most advise AGAINST it in the owners manual.HK for one actually says +P loads are NOT reccommended in their P30 pistols, even though their handguns are ridiculously overbuilt.
Going back to the round the OP used, it was a .40 caliber round loaded to full power 10mm speed. That would be risky shooting it out of a big burly stainless steel 4006, to say nothing about a Shield pocket gun.It wasn't just a .40 with some oomph, but a 10mm "short" loaded to respectable speed.
Use boutique ammo in a gun unready for it, and you'll get boutique results.AKA an explosion.