Trail Boss in .45-70
Q: I own a Marlin lever-action in .45-70 which kicks like a mule with fullpower 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/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 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 15 fps per 1/2gn increment. However, take your pick, but for Western action shooting 11.5gn seems just about ideal.