37 rimmed versus the 38-50

[samari46]

Need some info. I've been thinking about rebarreling a british #4 series action to the 37 rimmed which is the 303 British tp 375 caliber with no other changes except there is a small shoulder with the 37 rimmed. Then up pops the 38-50 which also used 303 British brass but with no shoulder. I would more than likely have to shell out for a custom reamer, and dies for the 37 rimmed. Am I wrong in assuming that 38-50 reamers and dies are more available than the 37 rimmed?. Also what would be a good twist for either cartridge. I have a Douglas blank which has been semi turned but most likely redo it on my lathe. That barrel has near as I can measure with a very tight patch and cleaning rod is 1x12. I don't hunt anymore so just punch paper. I can remove the barrel from a British P14 for the project but the barrel is too nice to cut a channel near the receiver and would much prefer to do a barrel swap on two ERA actions one good action with bad barrel and the other has a crummy action with a nice barrel. So's I need your help regarding twists. Will only be for cast bullets and bullet weights 250 to maybe 300 grs tops. Thanks in advance for your help. O posted this on the assra forum but I think once I mentioned bolt actions the posts got misplaced. Frank

[Stephen Cohen]

The cartridge you intend using is close to my 375 Whelen which sports a 1 in 14'' twist and shoots very well with cast. I had intended to do a 303/375 but chose the Whelen on a Mauser action. I would suggest you stick with the basic 303 shell just opened to 375 as you will have less magazine problems. I have seen two Number 4 actions made into 303/375 and could not get the owners to part with them. Regards Stephen

[EDG]

The original 38-50 was probably designed for .377 to .381 bullets like the original .38-55.

Before heading down that trail make sure your land diameter is going to work with the pilot on the reamer.
Also make sure the twist is what you want. Most .375 barrels are 12" twist which may be too fast for lighter bullets.

[samari46]

I've been considering a 1x14 twist rather than the 1x12 twist on the semi turned barrel I now have. That one slugged out at .377 so might have been originally what the previously unknown owner was aiming for. And that is what prompted me to question the difference between the 37 rimmed and the 38-50. Thanks for your information. Much appreciated. Frank

[beltfed]

Actually, the 38-50 Rem Hep needs a 30-40K brass for forming it
as the 303Brit brass is too short.
On a P14 action, above are probably correct in suggesting a necked up 303brit to .375.
I personally would be fine with the 12 twist barrel you have. And .377 should be good with many cast bullet choices.
beltfed/arnie