When does lack of Gas Check change results?

[NuJudge]

Is the lube on the plain base .375 going to break down and result in a lot of leading at 1900 FPS? I cast everything hard, and I usually just use 50/50 Alox-Beeswax, but I'd lube in Green Cheese from the Moon if it would enable 2900 FPS.

The reason I'm asking, I am about to try a plain-based 375248 in a smooth barreled .375 H&H Mark X Mauser. An old Lyman manual I just re-read (45th Edition) gives loads that go up in the neighborhood of 1900 FPS using 3031 for the 375248. My results many years ago with plain based .30 and .31 bullets was that about 1400-1600 FPS, leading became extreme and accuracy non-existant. With gas checks, I've gone to about 2400 FPS in .30 caliber.

Since 1982, I've been shooting lots of plain based 366408's over modest charges of 4759 or 2400 in a 9.3x74R. I never had the guts to go over 1600 FPS. If I could get near 1900 FPS with the case plain base 366408, I'd forget about that other type of bullet.

[Junior1942]

>Is the lube on the plain base .375 going to break down and result in a lot of leading at 1900 FPS?

Yes. I've found 1600 fps to be the max velocity for plain based cast bullets.

[45 2.1]

Since 1982, I've been shooting lots of plain based 366408's over modest charges of 4759 or 2400 in a 9.3x74R. I never had the guts to go over 1600 FPS. If I could get near 1900 FPS with the case plain base 366408, I'd forget about that other type of bullet.

There are several ways to do that! Regardless of what you here on this forum. PM me with details of caliber, bullet and alloy about what you want to do.