That is INDEED a very good number.16.2 grains MP-300 with a 180 grain wide flat nosed & gaschecked home cast bullet sparked by a Rem 6.5 rifle primer.
20" Marlin Cowboy = 1720 fps
Just remember cast bullets run faster with less pressure when compared to jacketed bullets IN MOST GUNS. Start well below that and work up to it. Vhitvouri N-120 shares many of the same traits as MP300 in 357MAG/MAX, and the N120 burns a bit cleaner, but it is hard to find and more expensive. Both seem to appreciate a primer that is on the warm side of normal. I use 6.5Rems in the 357Mag and Rem 7.5's in the Max. Both them loads are MAX in MY GUNS, and I got there by systematically sneaking up on that charge.That is INDEED a very good number.
Haven't seen a lb lately, but I'll keep an eye out. Might be just the ticket for my limited supply of 170gr Speer Deep Curls.
I haven't looked at any of the actual load data for for MP 300, (as I don't have any). Are there any issues with low end loads, ala W296/H110? Or is it more like 2400'ish ??Just remember cast bullets run faster with less pressure when compared to jacketed bullets IN MOST GUNS. Start well below that and work up to it. .
I would not reduce 300MP, it is happiest when going full steam or real close to full steam. FWIW, I have never been a fan of 2400 in the 357's personally. When going mid range with a 357 I find Herco to be much more cooperative in the ultimate accuracy department, but that is me. I do not shoot any of the copper clad heathen bullets though. I make my own cast bullets. Cannot remember the last time I shot a jacketed bullet in a 357 actually.I haven't looked at any of the actual load data for for MP 300, (as I don't have any). Are there any issues with low end loads, ala W296/H110? Or is it more like 2400'ish ??
The only issue I have with W296 is that it doesn't reduce with predictable results like 2400.
I cannot tell one load at 1500fps, etc. from any other load at 1500fps. When you get a good heavy bullet going as fast as possible with W296, 2400, 4227, (and I suspect any other powder), recoil becomes distinctly greater. But I can't tell the difference. With 2400 in my magnum revolvers, I can back off a bit with acceptable accuracy, and slightly reduced loads recoil less, but they don't turn into a pussycat.Just a feeling, but I think 300-MP is a bit milder or, at least, less sharp than H110 and 296. But it's just a feeling.