Justin:
Welcome to the board. Hope that you will hang around.
As for your question. Please understand that velocity has very little to do with pressure. You can get good velocity with moderstae pressures, if you are judicious in your powder choice.
Just skimming through the Alliant Powder manual, under STS hulls ( which I use exclusively ) I find a load using Unique, that gets a quite respectable 1200 fps out of an 1-1/8 oz that is circa 7300 psi. For a duck load, 1-1/4 oz at 1200 fps can be gotten for 8400 psi with Herco. There are a a goodly number of good payload, good velocity loadings that are in the 7000-8500 psi range. If you use other hulls you can find numerous others.
Guns such as you describe , 2-1/2" 12, were designed for service with loads in the 9000-10,000 psi range. You will find the biggest issue is not the metal, but wood. Wood which has dried out, or has not been properly cared for or has gotten a bit oil soaked, can crack at the head when you subject it to magno-blasters.
Is high velocity worthwhile? I think if you will look at the basic physics here, you will see that the high velocity loads kick a good deal more , but by the time the pellet has reached 40 yards, the difference is inconsequential. The more rapidly projected pellets slow down faster.... drag works like that.
Good Luck
Regards
GKT
