Choked rifle bore???

I recently acquired an original 1830-1840's percussion half stock rifle in .35 caliber with 39" barrel. The bore on this rifle is very clean when viewed with my bore scope. A .345 ball in a .015 mink oil lubed patch is a tight fit for the first 18' or so of the barrel, and then it goes down to the breech very easily. I have tried larger (.350 balls) and smaller balls (.340) with different patch thickness but have the same issue. The small balls go down easier, but you can still feel the change in resistance about 18" down.
Accuracy with this gun was so-so (2" at 25 yds) and patches were totally shredded. I finally found a combo that shoots great. (.345 ball, .015 mink oil lubed patch, and a .36 caliber felt wad over the powder charge. I am now getting 1/2 dollar sized groups at 25 yards but the patches are still shredded. Could this barrel be choked in some way, with a larger diameter near the breech tapering to a tighter diameter at the muzzle? I have checked the rifling, and believe the twist is about 1:40.
Any info from you readers would be appreciated.

Could be but that wouldn't explain the shredded patches.

I have a Bill Large barrel that is choke bored and never had a problem with torn patches.

I would check for a sharp crown and give the bore a nice polishing with JB bore paste to see if the patch shredding will stop.

In Ned Roberts' The Muzzle-Loading Caplock Rifle he describes how muzzle loading target rifles, I believe for conical bullets, and perhaps paper patched conical bullets at that, were made to be tighter very near the muzzle. With a 1:40 twist rate, I think you may have such a rifle.

You may have to get a custom mold made, but you might try a .338 Bullet with a linen paper patch, but I think that will be too small.

LD

The Green River Rifle Works barrels were choked, and I have one in 58 caliber. It took some load development, but in the end it's the most accurate rifle I own, and I haven't been around any others that come close.

Here's the "trick" recommended to me, and it certainly worked for me. Though mine is a 58 caliber, a .575 ball rests on the muzzle without dropping down the bore. A bare .570 ball will hang on the slightest imperfection. Yet get about a third of the way down the bore with either of them, and the rod virtually falls out of your hand, the seating gets so easy.

The solution was a .562 ball with .018 ticking and a grease lube. A little firm to start, but handled with a firm push on a short starter or a choked-up rod. No tendency for the balls to move off the powder in carry, but the key seems to be that thicker patch and slightly smaller ball.

BB, what you describe sounds and feels like exactly what I am experiencing. The tightest ball and patch I can get reasonable started into the bore is a .345 ball with a .o15 ticking patch with Mink oil for patch lube. It loads just like your .58 as described, but what patches I have been able to recover were badly torn. The felt button over the powder helped with the accuracy, but the patches are still shredded and burned. I can't even get a .345 ball with .018 patch started without tearing holes in the patch from the rifling.
As stated earlier, the bore is very good for the gun's age, and I did spend some time with a mop using JB bore paste on the bore and patches with green scotch brite to polish the bore cause I thought there might be some rough rifling.
I may try some linen patches, cause I hear they are pretty tough.

Dunno what to say about the burned and shredded patches in spite of the felt button. Are you lubing the button too? If dry they might not seal so well as lubed. And is it true mink oil you're using or the mink tallow or grease from TOW? I greatly favor the grease in almost everything I shoot.

You might also try a folded, lubed patch under the patched ball, rather than the felt button. I'm guessing, but that might do a much better job in the "loose" bore.

I've never seen a burned or shredded patch from my GRRW 58, so I'm mostly guessing here. Sure seems odd to have the burning in spite of the felt button.

I have noticed a "pssss" sound (before the bang) when shooting patches that are dry vs those with lube on them. I'm sure it's from gas blow by.

Fyrstyk said:

BB, what you describe sounds and feels like exactly what I am experiencing. The tightest ball and patch I can get reasonable started into the bore is a .345 ball with a .o15 ticking patch with Mink oil for patch lube. It loads just like your .58 as described, but what patches I have been able to recover were badly torn. The felt button over the powder helped with the accuracy, but the patches are still shredded and burned. I can't even get a .345 ball with .018 patch started without tearing holes in the patch from the rifling.
As stated earlier, the bore is very good for the gun's age, and I did spend some time with a mop using JB bore paste on the bore and patches with green scotch brite to polish the bore cause I thought there might be some rough rifling.
I may try some linen patches, cause I hear they are pretty tough.

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Don't give up easily with the JB bore paste and scotch brite.
I don't think you can polish enough. You may have to make several trips to the range, with a scrub session in between until the tearing stops, but it will.

I am using Mink Oil grease from TOW on the patches, but have been using a dry felt wad (.36 caliber used for BP revolvers). I will try a lubed wad and also try the folded greased patch. I'm sure the reason the patches are shredded and burned is due to blow by. Maybe the greased felt or the extra patch will seal the bore better. Thanks for your great advice.

Fyrstyk said:

I am using Mink Oil grease from TOW on the patches, but have been using a dry felt wad (.36 caliber used for BP revolvers). I will try a lubed wad and also try the folded greased patch. I'm sure the reason the patches are shredded and burned is due to blow by. Maybe the greased felt or the extra patch will seal the bore better. Thanks for your great advice.

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I bet that does it. A dry felt wad isn't going to do much, but in my experience the greased ones are like good magic.

There are tapered bores and there are choked bores and there are ringed barrels.
Ringed are damaged , tapered and choked are lapped that way. In the later two were talking a couple of ten thousands is all.
Pope, a black powder cartridge shooter liked to lap in tapper through the whole bore where as others liked to bore and lap the barrel level with a taper at the muzzle in the last three inches with the last 1.5 inched level again.
Brockway and Warren were famous cap lock, muzzle loading , target rifle builders, who preferred the latter method after experimenting with a taper bore. All of these guns used false muzzles.
Pope actually loaded his cartridge guns through a false muzzle for a period of time then went to breech seating the bullet in later years.
A ringed barrel is usually visible externally but not always.
I always suspect ringing when a bore diameter change suddenly presents itself mid bore or so.

Choked bores involve lapping of the barrel and there should be no rough regions of the bore. It is possible that the crown at the muzzle is sharp and could use some relief there. Relief crowning is done simply with your thumb, some fine grit metal sandpaper and twisting the barrel while holding the sandpaper with your thumb. Clean it up and got back to the range.

I'm going to clean up the muzzle as you suggest, and try using greased felt wads over the powder to see if this eliminates the patch burn out and shredding. As stated in my original post, I have closely inspected the bore with a bore scope and can find no indications of a bulged barrel. The lands and grooves are quite clean for a gun that is close to 180 yeas old. I'll let the readers know how my next range session works out after making these modifications to the load and barrel crown.

tapered and choked are lapped that way. In the later two were talking a couple of ten thousands is all.

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When I first started this game I was advised by an old greybeard to lap a new barrel with polishing compound. We used a rod with a bicycle hub as the handle. That allowed the jag to turn and follow the grooves. I was told to pump a certain amount of strokes (forget how many, but not relevant IMHO) but always come about four inches short of the muzzle. That way the bore was very slightly larger than near the muzzle. I don't know if it made any real difference and gave up the practice long ago.

I've lapped quite a few bores and some mold cavities over the years and it takes a lot of strokes, rotations, lap changes and fresh charging to remove even a couple ten thousands over the whole bore or cavity interior.
I do know that when changing to a new lap or re-charging it you inter from the breech end , not the muzzle.
I even lap cartridge barrels from the breech end forward with special elongated lap slugs.
I have found that a level bore will shoot just as well as a choked bore in most cases with bullets or patched balls, and high spots in a bore will cause leading just past the constriction where it begins to open up in lead bullet shooting.
Interestingly I have also found that pitting in a bullet shooting barrel has very little to do with wither a barrel leads up or not. It is almost always do to a diameter change or other irregularity of some kind.
Buying a Hawkeye bore scope about a decade ago was a revelation to me in cause and effect about what I thought I knew of barrel interiors. Still learning about that!

It may need a lapping down bore where it tightens up and be blended into the rest of the barrel interior before it shoots it's best.
Such changes can also be minor pitch changes in the rifling from a hard spot in the barrel metal. These can deflect reaming and rifling cutters causing a bore dimensional change. A snug lap slug will stop cold in one of these situations.

Sounds to me like the bore ain't shot in yet brother.
Get 50 shots through it with JB paste on the patches.

B :thumbsup:

This rifle is close to 180 years old. I think it has had quite a few balls shot thru it over the years. I have put at least 200 thru it since I acquired it. I'll lap the bore with some JB bore paste again, but haven't seen any improvement in the patches since the last time I did it. Must have swabbed the bore at least 500 stokes withthe bore paste the last time.

you can still feel the change in resistance about 18" down.

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Based on what you have told us, I believe it may be best to send that barrel off to Bobby Hoyt for freshing out to maybe a .40 cal. That constriction will unlikely go away on it's own otherwise. This will be a good way to save an old rifle for many more years of enjoyment.

Fyrstyk said:

This rifle is close to 180 years old. I think it has had quite a few balls shot thru it over the years. I have put at least 200 thru it since I acquired it. I'll lap the bore with some JB bore paste again, but haven't seen any improvement in the patches since the last time I did it. Must have swabbed the bore at least 500 stokes withthe bore paste the last time.

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Assume nothing friend!

Besides, nothing laps a bore better than added high pressure :thumbsup: