It is not worn, just huge. Did they do this on purpose? Any chance of a load that will shoot in such a bore? Jacketed will do about 5" at 50 yards, but who cares about jacketed! Still poor accuracy. Maybe a pure lead bullet and a case full of 3F?
In the early years before metal patched bullets and smokeless powder, bore/groove diameters varied somewhat. Lead bullets and b.p. worked a ok in various bore diameters back then. By the mid 1890's mfg's. tightened up the barrel tolerances with the advent of the the newer cartridge technology.
I have a '73 Winchester made in 1882 which has an oversized groove diameter of .433". The b.p. load (40/1) that TFHarper mentioned works fine in my rifle, that is until the pitted barrel fouls out in about 10-12 rounds.
Fortunately, by rifle's chamber will accept bullets of .435" diameter. I had a mold modified to drop bullets of that diameter and they shoot better still.
I cast up some bullets. Just a tiny bit of tin. 427098. Made up some lube, real soft. Bee's wax, crisco, olive oil, lanolin, ivory bar soap and water. Used a case full of 3F.
The groups were on the order of 3" at 50 yards, with a flyer no and again. The loads were quite zippy. The lube really worked well. The bore stayed wet. I did not need to clean between shots. It took two parches to clean there bore to the point where the next patch came out clean.
Glad to hear that you had some success making that vintage, historic Marlin .44-40 work with b.p. and soft bullets with your home made lube, just like it did with original .44-40 b.p. ammunition when it was new!
I reload for the 44 colt and an early 44/40. If you switch to a hollow based bullet you will get a lot better results. When you fire the rnd, the gas causes the base of the bullet to expand or bump up and seal the bore and contact the rifling. I use a rapine mold #RAP430211 it cast a 211 gr. FN hollow base bullet. It comes out of the mold about 430, i size mine down to .428, i use this bullet in both the 44 colt and 44/40. I load them with BP and really have had excellent results. The 44 colt I am firing from is an early kirst konversion, when they made it in 6 shot 44 colt. It is on a uberti 58 remmington, the bore diameter is about 451 and the bullets bump up and work nicely. If i use a solid base bullet the rnds will key hole because they are tumbling in the barrel. I reload 38lc with a hollow base bullet also for a 51 conversion that I shoot.This is common with the old conversions, in 44 and 38 lc. The early ammunition was loaded with hollow base lead bullets because of this. In todays newly made repos chambered in 44 colt like the open tops and richard mason conversion being offered by cimmirron the barrels are 429. So it is not a problem. You could also try a heeled bullet, but molds for these are getting harder to find. I think buffalo bullets is selling these already cast and lubed if you want to give them a try and see how they work in your rifle
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