Slugging a bore on 38-55

[tokguy]

I've recently aquired Grandad's 38-55. He said that it "keyholed rounds and wouldn't shoot straight".

It work's great with Winchester jacketed 255 factory ammo; the only problem is the local "Bend-over Sports Store" wants 50$ per 20 rds. I can re-load much cheaper than that, but I've read about "Slugging the bore" to verify actual dimensions.
Anybody know any tricks for this procedure? I've got a decent shop Oxy-Acetelene, grinders drills etc so I think I can manage it. But any help would be greatly apprecieted.
Thanks tokguy

 

[Sly Old Fox]

"Slugging " a bore.

I've recently aquired Grandad's 38-55. He said that it "keyholed rounds and wouldn't shoot straight".

It work's great with Winchester jacketed 255 factory ammo; the only problem is the local "Bend-over Sports Store" wants 50$ per 20 rds. I can re-load much cheaper than that, but I've read about "Slugging the bore" to verify actual dimensions.
Anybody know any tricks for this procedure? I've got a decent shop Oxy-Acetelene, grinders drills etc so I think I can manage it. But any help would be greatly apprecieted.
Thanks tokguy

Years ago, I would plug the bore down about 1" from the muzzle, and pour melted sulphur down the barrell. Sulphur does not shrink when it hardens.

The problem with this old lever action is that you can't use a rod inserted from the breach to push the sulphur slug out. You could however try and insert a good under bore size hunk of lead into the chamber then tip the rifle down so that the lead weight rested againt the rear of the plug and sulphur slug. Shaking up and down should loosen it.

I know that there is also a commercial low melting point alloy (name escapes me) for making a cast of the bore.

For what it's worth...

 

[sunray]

Grandpa might have been using the wrong bullet diameter or un-lubed bullets. The .38-55 uses a .376" jacketed or .377" to .380" cast bullets.
To slug a barrel, you hammer a cast bullet or suitably sized lead fishing sinker through the barrel with a brass rod and a plastic mallet. Better to do it from the chamber end, but from the muzzle will do as well. The plastic mallet won't hurt the crown. Don't know where you'd get a cast bullet or if fishing sinkers come big enough. You'll likely want to work up a cast bullet load sooner or later.
Marstar lists Winchester 255 gr RN ammo at $35 per 20. Sold out, of course.
How's the barrel on that rifle?

 

[Eagleye]

Just get a Round Soft Lead Ball [like those used for muzzleloaders] of a diameter larger than the bore. I used the .433" diameter Speer balls for mine. Lube the bore with a very light oil, and drive to ball into the bore from the muzzle with a plastic faced hammer. The excess lead will shear off and stay at the muzzle. Push the lead slug through the bore with a dowel or brass rod a bit smaller than bore diameter. Recover the ball from the breech and measure it up across the raised sections of the slug with a micrometer or even a digital vernier caliper, this will represent groove diameter. I cannot speak for an old rifle like yours, but in doing the two I have owned, the groove diameter is right around .3775". The one I have left, a 1980's Legendary Frontiersman, has a groove diameter of .3772" My LF 38-55 will shoot the Barnes Originals in both diameters [.375" (for the 375 Winchester), & the .377" (for the 38-55)] It shoots the larger bullet slightly more accurately than it does the smaller bullet. I have shot 1" groups with the .377" bullet at 100 yards. I tried some of the .375 diameter 220 grain Hornadys (for the 375 Winchester), and they definitely keyhole in my rifle. It is noticeable at 25 yards already, and you couldn't hit a barn door if you were inside the barn!! For Cast bullets I like them at .378" or .379" I have some very good 385 grain flat nosed bullets cast in Lyman's 375449 mold. these wear a gas check, and are sized at .3785" They are very accurate in my 38-55 right up to max velocities, which are in the 1650 fps range with H322 or Benchmark Powders. FWIW, I have heard of groove diameters as large as .381" in some 38-55 rifles. If you have an exceptionally large groove diameter, no jacketed bullet available is likely to shoot well. Cast and sized .001 - .002" over groove diameter will be the answer. Hope this will help you out. Regards, Eagleye.

 

[tokguy]

Thanks for your help, all; it is much appriecated.
tokguy

 

[Al-Sway]

The other possibility for the keyhole problem is a worn muzzle due to cleaning. This might not show up when you are slugging the barrel from the muzzle.

 

[stocker]

Get assembly/disassembly instructions for model 94. Take out the breech block. Then you can slug from both ends.For an old rifle it is advisable to take about 3 slugs for measurement. First one in the first inch or so of rifling in front of the chamber, another midway up the barrel the last near the muzzle. Drive each slug out the opposite direction that you started them. You'll find out if the throat is worn, the muzzle is worn etc. A chamber/throat and start of rifling casting with Cerrosafe can also tell you a lot.

 

[hunter64]

Here are the best instructions to disassemble the model 94 that I have found on the internet. http://www.castbullet.com/misc/tdown.htm

The only difference with your rifle is the flat main spring and not a coil spring as is noted in the text. I studied this a couple of times looking at the pictures with rifle in hand and mentally going thru each step before I proceeded the first time. If you are mechanically inclined then I would suggest doing this anyway to get all the years of gunk and grim out of there and at the same time you can slug the barrel.

Hardest part of the whole disassembly/reassembly is when you get to the flat main spring/hammer/trigger reassembly you need three hands to put it in and compress the spring. If you don't have a helper then get a pair of needle nose vise grips and pad the jaws somehow, I just wrapped tape around them a couple of times. As you are putting the trigger assembly in you can compress the spring with the pliers and it makes life a whole lot easier.

 

[senior]

The other possibility for the keyhole problem is a worn muzzle due to cleaning. This might not show up when you are slugging the barrel from the muzzle.

That's also very good likely-hood!
Sit a .375 cal 220 Horn bullet in the muzzle & hope it doesn't fall inside
Most old Winnys I have slugged measured .378-.381, VERY few of them would shoot a Horn 220gn bullet with-out tumbling, & Barnes .378? caliber bullets are double the price to buy!
I had a friend that made up a bullet "squisher" out of an old Die of some sort. You simply dropped a jacketed .375 Horn into it & ran the press arm down & majicly out popped a .378 bullet. Those shot very nice out of my 94