I load 28gr of Reloader 7 behind a 300FNGC for around 1850 FPS. That’s in reformed 30/30 cases. 375Win brass is a little thicker so you might drop it back to 25gr and work up. It’s a punchy load in a light carbine. Accuracy is brilliant.
The 375Win has a long throat, presumably designed to blow off pressure quickly, much like the 458 Win Mag. It’s Winchester’s answer of making a short case perform like a longer one. The throat is so long that you can’t load a bullet out and have it touch the lands and still cycle in a levergun. This problem is exacerbated in straight wall designs. The best way to get accuracy in these situations I find is to load as large a diameter pill that will still chamber freely and cycle. This helps centre the bullet in the chamber and align it with the bore rather than having it slump to the bottom of the chamber. A longer cast pill with a bore riding nose is better for accuracy as the front engages the rifling while the base is still supported in the case.
FYI the throating in the 38/55 is totally different to that of the 375Win and the standard twist rate in a 38/55 is 1 in 18”.
Most mould designs in this caliber are designed for the 38/55 and have a relatively short nose. You really need a Lee FCD so you can crimp in place to load to 2.55”.
I’ve shot fallow deer with mine and there was no sign of the bullet pulling up in game of that size. Penetration was complete, even on quartering shots. I need to take it out more but with ageing eyesight I tend to hunt mostly with scoped rifles.
I purchased a good mould for this caliber but have yet to try it on game. It’s a 250gr HP mould. With a suitable alloy it should provide rapid expansion and good penetration over a wide range.
Last edited by JFE; 04/21/20.
