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I’m a fan of vintage 38-55 Winchesters, have owned quite a few and shot them all, and managed to resolve accuracy issues on all of them. By that, I mean that I’ve seen some rough and oversized bores that at first gave poor accuracy, but was able to get five-shot groups at 100 yards of less than 3 & 1/2″ with all of them, no matter how bad the bore. Here are my thoughts …
- If your factory jacketed bullets are all over the place, then I strongly suspect your groove diameter is a little oversized. I’ve slugged them up to .383″, and I’ve mic’d factory jacketed bullets at around .375, though these were Dominion bullets. Put those two things together and you’ll have problems with accuracy.
- Do not use hard-cast bullets. Pretty much all bought cast bullets will be hard-cast. They do not bump up to fill the throat and you will get some blow-by and reduced accuracy.
- You need soft cast bullets (pure wheel weights, air-cooled) so they will bump up to fill the throat.
- IMR 3031 has too slow a burn rate to adequately bump up the bullets. You should try 5744, or IMR SR4759. Even IMR 4198 might be a tad too slow. The problem with slow burn rates is that the peak pressure is not high enough to adequately bump up the soft cast bullet to seal the throat/bore.
- Stay away from bevel base cast bullets.
- Gas checks help but not as much as soft cast bullets.
- I size my soft cast bullets to .380 and those will give me 2 & 1/2″, five-shot groups at 100 yards even out of a bore with .383″ groove diameter, simply because I use a fast enough powder, coupled with soft cast bullets. The only bore this did not work in was a .385″ groove diameter vintage Marlin . For that I had to move up to .382″ and bump up to get sub-3″ groups at 100 yards.
- A big “cheat” is to use slightly slower powders like IMR 4198 or even IMR 3031 and use a single sheet of 1-ply toilet paper loosely rolled and folded and then inserted into the case before the bullet is installed. This will act as a flexible gas check, as the TP gets pushed into any possible gas-leak gaps by the high pressure, preventing blow-by and significantly improving accuracy for really bad bores. I’ve used this technique in even a moon-scape, sewer pipe 44 WCF original ’73 to get sub-4″ groups at 100 yards. TP usually improves accuracy, but it usually ups the velocity by about 100 fps due to increased burn efficiency. Make sure, however, that the TP is loosely rolled and folded, so that the powder isn’t perfectly held back against the primer. If you hold the powder perfectly back against the primer by using something like cotton filler, it gives very nice consistent burning, but a pressure wave moves forward at ignition, reflects off the base of the bullet, producing a standing pressure wave with double peak pressure, and starts creating a thin little ring inside your chamber wall where the base of the bullet is. You will begin to notice this slight ring on your brass cases at the location where the base of the bullet sits. This isn’t hearsay; I’ve actually observed this ring progress over several dozen shots. I was using cotton to keep the powder perfectly against the primer. That is why you don’t use cotton, and use loosely rolled and folded, TP instead. You can also ring your chamber by pointing your rifle straight up into the air and firing for the exact same reason–a standing reflected wave with double the pressure at the base of the bullet. I’ve not done something stupid like firing my gun straight up into the air, but I’ve read of some who did it and ringed their chamber with a single shot. It is caused by the pressure wave reflecting off the bullet base creating a double-amplitude pressure wave at that point. Normally, the powder is not perfectly seated against the primer with an airspace between it and the bullet, so you don’t get the standing pressure wave off the bullet base. Nor will you get this for cases that are pretty much full, like modern rifle cartridges, or even the 30-30.
- I’ve used a ton of TP-loaded cartridges in the 38-55, 45-60, 45-70, and 44-40 … probably close to a thousand rounds in vintage Winchesters, and never had a problem. However, I’ve moved away from TP and go with a medium burn rate powder instead such as 5744 (my favourite for choreographed burn consistence) or SR4759. If all else fails, however, TP loosely rolled and folded (single ply) is your huckleberry.
I totally agree with Kirk about using toilet paper in any black powder cartridge when you are using smokeless powder. Through trial and error I have found out just how much of a sheet to use. I fold then roll the TP into a tube shape just long enough to gently fill the space on top of the powder and below the base of the bullet. The load is not compressed but it fills the large void. You will see a fragment of TP come out un-burned sometimes when you fire the cartridge. I haven’t had any problems with hard cast bullets but I make sure they fit correctly to my bore .001″ over the slugged measurement. I generally don’t have guns with really bad bores. Some do have pitting but all have plenty of rifling. When you slug the bore pay attention to the pressure needed to move the slug through the bore. You may have some spots looser than others. I always try 3 different powders when I am trying to find out what my gun likes.
Kirk,Chuck, thanks for the info. The Montana .380 & .381 bullets are due in on Friday. I was unable to find any 5744 or 4759 powder. I have some Sports World Buffalo Rifle due in from Powder Valley I will try. Great reports over on the cast boolit (bullet) site by a bunch of shooters. Several using for 38-55 cast bullets. They are using it as a replacement for the above discontinued powders.It is reported to be also good for reduced loads in other calibers. It will be a couple of weeks before I can get to my private range to test things as there is still too much snow up there (Vermont). Oh, those bullets are with gas checks.
Please keep us posted. I am interested in this topic and your road to accuracy with your 38-55
Well,I’m back with a range report after getting the proper components for the 38-55 accuracy problem. I started by firing a few factory rounds using the lead sled. As expected all over the target, 12 inch group. Next I shot 3 rounds with .380 MBW 265 gr FN-GC, BHN-22 bullets, 26gr RL-7, all 3 in the black! Velocity 1688. Next I shot same load with .381bullet, 2 inch group, same speed. It likes that .381 bullet. I also tried same load with Shooters World Buffalo Rifle powder 20 gr, even more accurate. Velocity 1366 with POI three inches lower than RL-7 load. That Buffalo Rifle powder looks and acts like 5744. These shots were at 50 yards with original open sights and 72 year old eyes using reading glasses. At 50 yards I can see the target well enough but not beyond 50. I need a peep sight. Will a peep work ok on a takedown 94. Thanks gentlemen for all your help.
Now, that’s a good report! Glad you were able to resource some oversized boolets to try
Technically, the glass is always full; half liquid, half air....
WACA #10293
If your takedown is tight, the tang peep will work well.
I’m pleased to hear you are shooting well with your rifle.
Sounds like you are heading in the right direction. Given your results, your groove diameter is probably .381 or thereabouts. You can either hardcast sized to .381 or soft cast sized a bit smaller, but it will bump up. A tang peep sight is definitely a good thing. I’m 65 years old and have tang peeps on all my old lever guns that I shoot. Once you get a tang peep installed and adjusted in windage and elevation, I’d be real interested in what you get for a 5-shot group at 100 yards. That is my own personal baseline with which I compare all my rifles and loads.
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