That technical manual describes the loads, not the max pressure by SAAMI specs. Every load has a specified component and max pressure (the latest 300 Win Mag sniper ammo spec'd by NSW Crane upped the max pressure to 68k PSI).
I'd trust someone with Quickload over that manual as to exactly what the max pressure of 46 grains of WC846 behind a 147gr FMJBT lit with a #34 primer. It could very well be 50k psi, but I'm guessing when the Army went from CUP to PSI they just changed labels instead of converting.
EDIT: From Hogdon's reloading data, BL-C(2) is the cannister equivalent of WC846, and notice the pressure is measured in CUP not PSI.
150 GR. NOS BT Hodgdon BL-C(2) .308" 2.800"
45.0 2661 40,200 CUP 48.0 2839 50,000 CUP
Now you can't really compare CUP to PSI without a direct measurement, but look at the max loads for these two powders with the same max velocity.
150 GR. NOS BT Hodgdon H4895 .308" 2.800"
43.0 2742 43,200 CUP 45.5 2870 51,000CUP
150 GR. NOS BT IMR IMR 8208 XBR .308" 2.800"
40.0 2604 45,500 PSI 44.5C 2870 60,800 PSI
Now I can't prove it one way or another, but it looks like the TM just changed CUP to PSI at some point.
Machine guns are awesome until you have to carry one.
Last edited by Jimro; June 2, 2012 at 05:23 PM.