Is only in the 50,000 to 52,000 psi range. This ain't no high pressure load. To get a 400 gr pill going around 2150 fps in a 405 Winchester you are going to have to get to a pressure of 60000 psi +. The throating job is just to allow you to get a little more powder in. Still need to bump the pressure a bit though. In simple english it means you need a faster powder.

Let me lay it out for you.

W748 in the will hit about 51500 to 54000 psi in your new longer throat chamber with a powder charge of 60.5 grains. This is ~ 107% compressed load too.

Muzzle velocity for this load with 400 gr Woodleigh - 2000 to 2040 fps . Of course you can pre-heat your barrel to 180 F and probably get 2150 fps. Of course that assumes the rifle / case holds together long enough for the bullet to exit the barrel.

Good luck, and waiting on your creditials.

Scott

-EDIT- found a mistake in the simulation. The corrections are bold faced. Sorry about that.