Winchester M1894 leading problem

[cwskirmisher]

M1894 in 38-55. I am shooting 19 grains of 4198 under a 250 grain .381 Lee RNFP lubed with Carnuba Red. My alloy is 50/50 WW/Pb. I am getting decent accuracy for the first 4 or 5 shots, then the groups open up. Looking down the barrel with the action open, it is very dirty and lots of 'debris'. I think I may be stripping the rifling?? Should I use a harder alloy? I am trying to keep the alloy on the softer side for hunting expansion.
The barrel cleans out fairly easily - a couple of patches soaked with Butch's followed by brass brushing, then dry patches until clean. Gun then shoots just fine and accurate again for a few rounds.
The barrel slugs .378-.379.
Staying away from J-bullets - this gun is a 1906 manufacture and does not have any markings on the barrel indicating safe for smokeless - so am keeping to boolits and powder that gives low/BP pressure curves. I have fired a few commercially available J's (loaded to low pressure/speed), but they are only available in .375, and accuracy was marginal.

Help/Comments please.

[Bullshop]

When you clean the gun do you see lead on the patches? If you were stripping you would see lead on the patch.
I think it is more likely that your pressure is too low for the powder to burn properly and so you are getting too much carbon fouling.
I have the same problem using 4198 in a 22 hornet. The burn rate is too slow for the hornet so the pressure is too low to burn the powder properly. Accuracy is good for a short while then drops off. Cleaning the barrel brings accuracy back for a short while and so on. Sound familiar?
I may be off track because I am not looking at any data for the 38/55 and 4198, I am just guessing. If you still have room for powder and safe pressure assumed I would work up a bit, or try a mag primer. I do not think the boolit hardness is the issue.

[Bullshop]

It may be a good idea to compare data for the 38/55 and the 375 Win with the same boolit and powder. That may give a better idea of what a top end load may be before actually working up to it.

[cwskirmisher]

When you clean the gun do you see lead on the patches? If you were stripping you would see lead on the patch.
I think it is more likely that your pressure is too low for the powder to burn properly and so you are getting too much carbon fouling.
I have the same problem using 4198 in a 22 hornet. The burn rate is too slow for the hornet so the pressure is too low to burn the powder properly. Accuracy is good for a short while then drops off. Cleaning the barrel brings accuracy back for a short while and so on. Sound familiar?
I may be off track because I am not looking at any data for the 38/55 and 4198, I am just guessing. If you still have room for powder and safe pressure assumed I would work up a bit, or try a mag primer. I do not think the boolit hardness is the issue.

Yes, all the patches initially come out grey - it is not unburnt powder or carbon fouling. I have shot up to 24 grains 4198 (I think that's max for this gun) with the same result. I also have tried 4895 with similar results - good accuracy though, but I was concerned about the pressure on the action so wanted a slower burn and slower pressure rise rate.

[Bullshop]

Well thats interesting. Have you done a chamber cast to see how long your chamber is compared to the brass your using?
I had problems getting a 38/55 to shoot consistantly good groups until I found I had a long chamber and got brass to fit it.

[missionary5155]

Greetings
You might want to slug the throat area also. Put a wood down inside a case to support the boolit and see if it is a snug fit for the boolit into the throat. I would not be surprised if it was as fat as .382. My 1903 built 94 38-55 is that. Maybe worn and corroded but a .383+ boolit shoots nicely and I use 50/50 mix also.
I was able to get OK groups with COW on top of the powder with just a tad of compression with the seated boolit using an as cast .381.
Your load is not excessive. I have used 23 grains in my rifle and see no undue pressure signs.
The problem you may encounter is how fat a loaded cartrige your chamber will accept. With a fat throat you may have to thin case necks (easiest) or ream the chamber neck area or set the barrel back one turn .
Do not be to overly concerned about the bore /groove as that soft boolit will easily swage down. Lapping the mold (start with one cavity) will give you fatter booits to work with.

[cwskirmisher]

Greetings
You might want to slug the throat area also. Put a wood down inside a case to support the boolit and see if it is a snug fit for the boolit into the throat. I would not be surprised if it was as fat as .382. My 1903 built 94 38-55 is that. Maybe worn and corroded but a .383+ boolit shoots nicely and I use 50/50 mix also.
I was able to get OK groups with COW on top of the powder with just a tad of compression with the seated boolit using an as cast .381.
Your load is not excessive. I have used 23 grains in my rifle and see no undue pressure signs.
The problem you may encounter is how fat a loaded cartrige your chamber will accept. With a fat throat you may have to thin case necks (easiest) or ream the chamber neck area or set the barrel back one turn .
Do not be to overly concerned about the bore /groove as that soft boolit will easily swage down. Lapping the mold (start with one cavity) will give you fatter booits to work with.

I have ordered some new Starline long brass (2.125), and will load some with those to see if it makes a difference. I may also try a faster powder like 2400 or 4227 to help bump up the bullet better if it is not big enough for the throat.

[excess650]

I wouldn't depend upon a faster powder to bump the bullet up, but would rather chamber as large diameter as I could without resistance. Starline cases should allow larger diameter bullets than WW cases. Get some larger diameter GC bullets lubed with a good lube and try 'em.