375 Whelen Improved

[358WCF]

How much shoulder is needed for a positive headspace.

There is also a 400 Whelen. It's .411" bullets are considered max for an 06 case. Most of my o6 based Ackleys have .465" shoulders, so maybe a .416" bullet might work. Pretty much splitting hairs.

From American Rifleman 9-1-23


And a better & newer version r/clicked from the internet somewhere.

 

[Evan]

How much shoulder is needed for a positive headspace.

Not much, if you think about a pistol case that headspaces on the neck, that is only approximately 0.010” per side. A chamber needs only a few thousandths (0.003”) of total clearance for function at the shoulder or neck which for the pistol means maybe as little as 0.007” for holding headspace. Even the 375, with a ~0.460” shoulder and 0.410” neck diameter is at least 0.025” per side.

Edit: @358WCF posted some nice diagrams that probably more readily explain my point.

 

[ISS]

I was quite intrigued by the .375 Whelen Improved (along with the .338-06, .35 Whelen, .35 Whelen Improved, and the .400 Hawk ) years ago. I figured the .375 Whelen Improved would be a fine elk cartridge, but later wondered if available bullets in the 270-300 grain range would have expanded adequately at .375 WI velocities beyond 100 yards or so. Not much point in using such a cartridge if you're only going to use light bullets.

There have been a couple of articles in HANDLOADER magazine on the .375 AI with load data. The .375 AI along with the other big '-06-based wildcats are fascinating to work with. In retrospect, however, I would ditch all of the wildcats and choose a .30-06 with good 200 grain bullets. I think the '-06 it will do anything the wildcats will do performance-wise and may do it better and at longer range.