I recently acquired a very nice No.4 MK1 Enfield in full military trim produced at Maltby in 1943. It has a two groove barrel that is very nice and shiny with no pitting. The crown looks to be in good shape as well. I obtained the following measurements: Bore: .3025 Groove: .313 Throat: .315 Inside fired case neck: .319. I made sure all the screws etc. were snug and removed all traces of copper.
I loaded some Fat 30s that dropped at .315 and ran them through a .315 sizer. FWFL lube, Gator gas check, WLR primer, 16.0 grains of 2400 with 1 grain of dacron. Boolit seated to 2.919 (base of case neck). Fired from bags at 50 yards. 10-12 inch groups with all boolits making nice long keyholes. No leading. I thought well, obviously I need a bigger diameter boolit to get more stability.
So, I paper patched a 311284 as cast with two wraps of .002 notebook paper. The final diameter was .320. I was thinking, longer boolit plenty fat, should stabilize, but probably won't chamber. Well, I seated it at 3.013 in unsized cases, it chambered fine and was further seated upon chambering to 2.928 firmly against the lands. Good neck tension. Again, 16.0 2400 with 1 grain of dacron. This time I was pretty confident I had made the necessary adjustments for success. Fired from bags at 50 yards. Two to three foot groups. No leading. Mostly keyholes or oblong entry, but not all of them.
I'm obviously left scratching my head on this one. This rifle has an above average bore and the dimensions seem pretty well in line. It has a great trigger as military rifles go. I would really appreciate some thoughts and ideas on which direction I need to go next. By the way, this is my first experience with the .303 Enfield. And I must say, I really like this rifle. And that's saying a lot considering how it's shooting.
Keith