Great tool... no .30-30 AI profile.

by AaronB, Monday, May 11, 2026, 19:11 (11 hours, 38 minutes ago) @ JohnKDM

No matter, I decided to modify the case volume for the existing .30-30 profile to give me the pressure curves I was asking for.

Of course I wasn't satisfied with guesstimating the "5-10% increase in case volume" that's the usual claim for the AI improvements, which is why I was in the shop filling up empty cartridge cases with water and weighing the results as a proxy for case volume.

I figured five ordered pairs were sufficient, for .30-30 Win vs. .30-30 AI. My plain-jane .30-30 cases held an average of 44.98 grains of water, and my AI cases held an average of 47.48 grains. The spread on the values wasn't great... mixed headstamps, you know. The Remington-Peters cases seemed to be the roomiest, and the Federal Cartridge were the most cramped (i.e., the stoutest brass).

The resulting calculations gave me loads predicted to yield 1800 fps while launching my Heavy Thirty out of a .30-30 AI case... 22.0 grains of IMR 4198, or 26.0 grains of IMR 4895. The 4198 load was surprisingly high-pressure at 43,729 psi. The 4895 load was much lower at 32,943 psi. In the interest of safety, the IMR-4895 load will be my load of choice for this application.

Thanks for putting me onto this calculating tool.

-AaronB