Dirtfarmer,
The mil-surp H4831 varied some in burn-rate, probably because unlike commercial powders, it wasn't blended with previous lots to make burn-rate similar from batch to batch.
A couple years ago I opened my last can of the military powder, and tried the same charge with both it and my present in my O'Connor Commemorative Model 70, 61.0 grains, with H4831SC and the 130-grain Hornady Spire Point. The old powder got almost 100 fps more muzzle velocity, indicating it's faster-burning.
In general, I've found the latest H4831 (whether SC or standard) to produce pretty slow velocities and mediocre accuracy when using Hodgdon's data in the .270. Hornady, however, lists 62.0 grains as maximum with 130's, and with their data velocities and accuracy are pretty good.
You are 100% correct, with 55.7 of h4831 and 150's horrible accuracy. I ended up at 58.0gr behind a 150 Sierra 4 bullets all touching 5 bullet out by 1/4 inch or so. Shot out of a model 70 featherweight classic. I'm sure some will be by and say I'm going to blow myself up.
