butlersrangers wrote on Jun 8
th, 2019 at 6:36pm:
. . . Any figures on chamber pressures with IMR-4895 and 220 grain projectiles?
No pressures from Sierra manual (testing done in 22" Krag, no pressure gun).
QuickLOAD gives estimates (in CIP piezo psi) -
Cartridge : .30-40 Krag
Bullet : .308, 220, Woodleigh FMJ 65
Cartridge O.A.L. L6: 3.089 inch or 78.46 mm
Barrel Length : 22.0 inch or 558.8 mm
Powder : IMR 4895
Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.941% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !
Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms
-11.8 72 30.00 1837 1649 27694 6150 95.8 1.682
-08.8 75 31.00 1891 1747 29864 6369 96.8 1.631
-05.9 77 32.00 1945 1848 32192 6574 97.7 1.582
-02.9 80 33.00 1998 1950 34686 6765 98.5 1.535
+00.0 82 34.00 2051 2055 37364 6940 99.1 1.489