BB94 throat length

[omgb]

OK, so I was tinkering around my bench lamenting that none of my cast loads with either Lyman or RCBS bullets want to feed correctly in my early BB 94. I decided to see how far out I can seat the bullet and see if that helps. Dang! I was using the crimp groove but after crimping back in the middle of the last lube groove before the crimp groove, the gun cycles perfectly. This is a full 1/4" more length. I then worked on getting it out there as far as it would go and as close to the rifling as I could get. I managed to move it out to the ver beginning of the last lube groove before the crimp. This is 5/16th longer out than the crimp groove. That gentlemen was a whole lot of jump for a little old piece of lead to make. I can hardly wait to try these new loads. What do youwanto bet that groups shrink a whole bunch? I'll bet leading goes away too. Dang! I wish I had checked that before. It never dawned on me that Win would build so much lead into their barrels.

[TedH]

Yep, mines the same way. It feeds 220 Hornadys fine, but I cant seat the RCBS bullet in the crimp groove, way too short OAL to function properly.

[omgb]

Seating these farther out has got to improve the accuracy. In the end, I'll bet I end up buying a custom LBT mould with a crimp groove where it belongs and a chamber filling first band.

[Billwnr]

Interesting!! The rap on those rifles was that they wouldn't group better than 2 1/2 inches at 100 yards. It just might be because of the bullet jump. I'll check mine out also.

[Dutch4122]

When I measured the throat in my M94 BB .375 Winchester (early angle eject pre-safety model) I used a jacketed slug seated backwards. Measurement I got was .418" long throat repeated three times. My Father's Marlin M375 throat measured over 4 tenths of an inch as well using the same method.

Don't be surprised if you get the same results with your Winchester or Marlin chambered in .375 Winchester.

Hope this helps,

[JFE]

I read somewhere (I think it was in an article by Paco Kelly's on the 375BB) that you could use the longer 38-55 brass in the 375 BB chamber. also due to the thinner walled cases, the 38-55 allowed higher powder charges. If this is accurate it may get around the long throat issue as 38-55 is quite a bit longer than the 375BB.

Joe

[omgb]

Here's a shot of what I found when I reverse seated a bullet. That's a whole lot of free bore. There is no way in "you know where' that i can seat this bullet out far enough. Now for the good news, seating out to the first lube groove and using H4895 got me three shots in a line stretching over 3" at 100 yards. I need a scope to do better.

[Frank46]

I have a sneaking suspicion that winchester made the throats on the BB94 long to keep pressures down. Haven't measured mine but using the MKI eyeball it appears LOOOOONG. Still too darn hot down here, it hit 100 this afternoon, and this fool was out cutting the grass by the bayou. They caught a 6' alligator this week, guess the heat must be chasing them out of the shallow waters. Frank

[omgb]

It was over 100 here too. Not a cloud in the sky. I nearly fried my brains out on the range. Still, the Rh is low so the heat was tolerable.

[26Charlie]

I think they chambered the .375's long so .38-55 brass wouldn't cause problems, and jacketed .38-55 loads would fire (although I haven't tried this). All three .375s of mine - Ruger #3, Win M94BB, and Marlin M375 will take .38-55 brass. I crimp the cast bullets according to their OAL needed - the Lyman 375449 gets crimped in the crimp groove, the RCBS 37-250-FP gets crimped in the 2nd groove because it has a shorter nose.
I can get 35 gr. of 3031 in the RCBS loads, whereas the Lyman only permits 33 gr. crimped in the fashion described.