Q: I own a Marlin lever-action in .45-70 which kicks like a mule with full-power reloads. Since I intend taking up Western action shooting I’d like to make up some light-recoiling loads.
I’ve been told that Trail Boss is the best powder for this because it is bulky and doesn’t need fillers. Could you suggest a decent load using the 405gn LFP bullet?
A: You are right. Trail Boss is a high-density powder and this is the secret of its success.
The granules, which resemble miniature doughnuts, have a bulk density of 0.3 grams per cubic centimetre. Many of the pistol powders we previously used have a density of 1g/cc or more.
Don’t confuse this term with loading density, which is the amount of available space in the cartridge case, which is filled with powder.
Using ultra-fast pistol powders increased the amount of empty space, giving rise to problems due to powder position in the case unless you used a filler.
By my rule of thumb, loads closer to 100 percent or even lightly compressed tend to improve accuracy.
In the .45-70 with a 405gn cast bullet, the maximum load of 13gn (which is pretty much a case full) yields 1000fps.
My load development started with 11gn, which gave 940fps; 11.5gn got 965 and 12gn gave 1015fps, for an increase of roughly 15fps per 0.5gn increment.
Take your pick, but for Western action shooting 11.5gn seems just about ideal.