- Dec 1, 2009
- East Tennessee
Need help, I'm confused with some info i have. My old horndy manual list's 300 win mag 71 - 79 grains of IMR 4350 for a 150 grain bullet. Top velosity was 3400 fps. I had started on a new rifle and load. Shot some single rounds of the low charges and started loading 3 each starting at 75.5 grains. I didn't show any pressure at 75 grains so i moved to 75.5. Hadn't set up the chronmagraph until then. That set of 3 averaged 3400 @ .043 inches 100 yds. I had 3 more loads at 76.5, 77.5, 78.5 but was afraid to shoot them. It didn't show hardly any pressure up to 75.5 but just a bit of shin on the base. No sticky bolt or hard to open or flat primers. When I got home and got to checking I couldn't find any where that list above 74 grains for that load. What's going on? I've loaded from this manual for a lot of years and never had a problem.