madsenshooter wrote on Jan 18
th, 2018 at 9:37pm:
. . .What I'm thinking is fill up that space around the boat tail with powder. It'll be there, under pressure, even when the neck is expanded, and as the bullet travels through the neck and starts into the throat. That should further minimize any chance of yaw. . .
I wish I had quickload to play with, it'd be interesting to see what those ball powders would do with a 174gr bullet out of a 30" barrel. . .
I think that's pretty insane. Granular powder, especially spherical, has about the structural stability of dry sand - if sand could burn away.
In my limited experience (only been handloading since 1958), using super-slow powders in low-pressure, relatively small cartridges is a waste. They never get hot enough to burn much before the bullet exits the muzzle.
Here's QuickLOAD estimates for H870 (supposedly very close to WC860) in .30-40 with the 175 Sierra BTHP. Note the penultimate column showing the % propellant burnt.
Cartridge : .30-40 Krag
Bullet : .308, 175, Sierra HPBT MatchK 2275
Cartridge O.A.L. L6: 3.089 inch or 78.46 mm
Barrel Length : 30.0 inch or 762.0 mm
Powder : Hodgdon H870
Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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
-10.0 90 42.30 1679 1095 14434 3309 52.9 2.469
-09.0 91 42.77 1698 1121 14809 3393 53.6 2.441
-08.0 92 43.24 1718 1146 15198 3477 54.4 2.413
-07.0 93 43.71 1737 1172 15596 3562 55.1 2.385
-06.0 94 44.18 1756 1199 16012 3648 55.9 2.358
-05.0 95 44.65 1776 1226 16439 3736 56.7 2.330
-04.0 96 45.12 1796 1254 16880 3824 57.4 2.303
-03.0 97 45.59 1817 1283 17339 3914 58.2 2.276
-02.0 98 46.06 1838 1313 17810 4004 59.0 2.249
-01.0 99 46.53 1860 1344 18300 4096 59.8 2.223
+00.0 100 47.00 1881 1375 18808 4189 60.6 2.196