Fellas, i just got off the phone with Glen Jensen at winchester Tech. He stated that my 1980 win. 94 has a bore of .368" and a groove of .376" with a 1 in 15 twist. My current plain based bullets are .379 i have tried them and they are fairly accurate but as you can see in another post i went a little hot and leaded my bore somewhat. Any suggestions on shooting a plain based .379" in a .376" barrel?? If anyone is interested he is at 1-800-945-5237.

Mark,

you ask: Any suggestions on shooting a plain based .379" in a .376" barrel??

F: The difference of 0.003 between bullet and groove diameter is not a major problem for your rifle unless accuracy itself suffers unduly, and you say that this is not the case.

I used to have a 40/65 with a conventional 0.409 groove diameter. Due to unusual throating I finally got my best accuracy with bullets of 0.414 diameter.

Shooting cast lead bullets is full of variables, bullet size being one of many. I happen to think that a fellow may tailor a load/rifle to accommodate any minor difference in the so-called "ideal" of shooting a bullet just 0.001 over groove diameter for best accuracy. Such things may be dealt with by tailoring the load to your particular set of components.

Good afternoon,
Forrest

Mark, as you've been told by previous posters, clean the lead out with chore girl/boy pot scrubber strands on a brush. You need to slug your bore and you need also to give us some load data to digest. Factory bore specs are one thing, actual is sometimes quite different. I don't know what velocity you're trying for, but you should be able to get 38-55 velocity fairly easy with plain base bullets. I shoot a 375 Marlin (375 Winchester) with a microgroove barrel and my hunting loads are 1800 fps with a Lyman 375248 pb bullet. While not one hole accurate, accuracy is plenty good for hunting and I get very little leading. Regards, Woody

The bore size is not an issue as long as, like leftoverdj said, you have adequate neck clearnace.

Reduce velocity.

I shoot .313" bullets in my .308" barrelled .32 H&R with no problems and accuracy is fine. I'm pushing a 100 grain plainbase at 1600 fps.

I had an experience with my 38-55 (1903) Winchester like this , I figured : What the hell , this old stove pipe has a shotout barrel or the factory tolerances are sloppy anyway ....WRONG !I ordered a .379 sizing die and was unable to close the action even halfway ! Necksize was way too big with the 379 bullet and even the 377 bullet is really tight , but shoots like dream (comparatively speaking) with no sign of high pressure, slug your bore or you`ll be fishing in mud water !