Relatively new temperature-stable powders appropriate for the .375 Ruger include IMR 4166, Reloder 155, Winchester StaBALL 6.5, Alliant Reloder 16, and IMR 4451.
December 12, 2022
By Lane Pearce
When Editor-in-Chief Joel Hutchcroft reminded me that “dangerous game” is the theme of this issue of Shooting Times, I immediately thought about the .375 Ruger cartridge I’d reported on years ago. Since then, some new powders were developed that are just the ticket for handloading the round. So we decided I would revisit it for this column.
Hornady and Ruger jointly developed the .375 Ruger, and you could say it is a modern version of the honored .375 H&H Magnum. Its primary attribute is it can deliver essentially the same H&H “magnum” performance while fitting in a standard-length (.30-06) action.
My memories of shooting the .375 Ruger all those years ago were not all positive. The original Ruger Hawkeye African rifle I used featured a medium-weight, 23-inch barrel; express-style iron sights; and a trim, straight-grained walnut stock. It weighed about 9.25 pounds with a 1.5-5X scope. Plus, it had a thin, hard rubber buttpad. It kicked like a mule!
In fact, after firing about 50 rounds from the bench during the first range session, I was ready to call Joel and say he’d have to get someone else to do the report. But I sucked it up and eventually fired another 80 or so rounds, prepared the charts, and submitted it as assigned. I notified Ruger that the stock had fractured just behind the action tang, and the company promptly replaced the stock. I purchased the rifle and added it to my vault. A couple years later, I replaced the factory stock with a Hogue rubber overmolded Army drab green stock, and upon firing the rifle, I perceived the recoil was more like a “wimpy” .300 magnum. The Hogue stock has a thick and much softer rubber buttpad, and it does mitigate the felt recoil.
Advertisement
For this issue, I decided to try some handloads loaded with several new and improved, temperature-stable propellants. As you can see in the chart, I had several prospects: IMR 4166 and IMR 4451, Winchester StaBALL 6.5, and Alliant Reloder 155 and 16. The .375 Ruger features a common rimless, bottlenecked case—it’s just bigger than most. Prepping the cases follows the same process as you would with the .270 Winchester, .308 Winchester, and .30-06; however, since it’s really important that they feed and chamber easily when hunting prey that can bite, butt, or claw, I highly recommend that you full-length size your brass and weigh every propellant charge.
I chose to load a bit below max and seat the bullets to the manufacturers’ recommended COLs. A Large Rifle Magnum primer is recommended to reliably and consistently ignite the large powder charges, so I used Remington and Federal primers. The resulting minimal standard deviations tend to confirm the advertised claim that these powders are temperature stable.
The data chart depicts the velocity and accuracy results based on three, three-shot groups. Even though the felt recoil has been attenuated substantially by the Hogue stock, I’m not a glutton for punishment.
Advertisement
The two Alliant propellants included in the chart are quite new, so tested recipes for not-so-prevalent rounds like the .375 Ruger are not widely published. Speer does list Reloder 16 data for the 235-grain bullet (91.0 grains max at 3,154 fps); however, I asked a technical contact at Vista Outdoor if Reloder 155 had also been tested. The 82-grain test load I used was reduced from the max charge that was provided to me.
Reloder 15 is a popular medium-burn-rate propellant with closely similar start-to-maximum charge weights compared to Reloder 155. However, Reloder 15 is not temperature stable, so for extreme temperature conditions, Reloder 155 is a better choice.
Revisiting the .375 Ruger was actually almost a fun experience. I only fired 12 to 20 rounds during each visit to the range, and the Hogue stock prevented a bruised shoulder, even though the test loads were all fired from the bench. Oh, and I brought along other firearms to shoot while the Hawkeye cooled off between strings.
The current version of the Ruger Hawkeye African model is very similar to my rifle with one important difference. It’s fitted with a radial-ported muzzle brake to tame the recoil. Great idea! Now everyone can add this rifle to their collections and enjoy shooting a few(!) rounds.
