Bump/raised spot in smoothbore pistol bore

[zneufeld]

Hi all,

I just received this Sea Service pistol (purchased from another member on this forum, many thanks, sir!). We believe it was built from a TRS kit (Late Sea Service pistol), .62/20 ga. I am absolutely thrilled to have found one, since this will be a Christmas gift for a flintlock enthusiast buddy of mine who has wanted one since he was a kid.

I am new to smoothbores. I did a cursory cleaning today, and found a small bump/raised spot in the bore, about 2 1/2 inches from the muzzle. It almost looks like deposited lead, and some light brushing with a brass brush didn't affect it. It creates a slight catch with a patch and undersized cleaning jag.

Any ideas as to what it could be? Obviously, one doesn't get one of these pistols for great accuracy, so that's not really a concern. Just hoping to make some smoke and clang a target.

Here's the best photo I could get of the bore. It's the shiny spot on the bottom of the barrel.

 

[Phil Coffins]

Does it line up with a cross pin for the stock or pipe attachment? That’s the first thing that comes to mind.

 

[M. De Land]

It's probably the screw holding the loading rod pipe pushing into the bore from to long a threaded hole.
I bought a match pistol that had the same kind of deal where the barrel attached to the frame via screw. I sent it back and they rebarreled it for me.

 

[zneufeld]

Does it line up with a cross pin for the stock or pipe attachment? That’s the first thing that comes to mind.

It's probably the screw holding the loading rod pipe pushing into the bore from to long a threaded hole.
I bought a match pistol that had the same kind of deal where the barrel attached to the frame via screw. I sent it back and they rebarreled it for me.

Good points. It does almost line up with the foremost pin. I got a better photo, and it seems to be oval in shape.

 

[Musketeer]

That's weird. It does look like it could be the top of that foremost pin peeking through into the bore, or a thin hump of metal from the bore itself that's been pushed upward by said pin. It could also be that upon initial assembly the pin hole was drilled too high, causing the pin to go through the bottom of the bore rather than under the barrel, and whoever put it together repaired the damage to the barrel before relocating the pin to a proper location and just didn't grind down the repair weld inside the bore.

If you feel comfortable doing so, I would suggest removing the tang bolt and the two barrel pins, then pulling the barrel and seeing what the underside of it looks like. It's really not a difficult process, you just have to have a tiny punch or other rigid object smaller than the pinholes and gently try pressing the pins out of place, so you don't break little chunks of wood out around the pinholes in the process. Try pushing them from both sides of the stock and see if they seem to want to come out easier from one side or the other, also.

If it does turn out to be the top of the pin coming through, or a thin skin of barrel steel being pushed up by the pin, then I'm not sure what to tell you. If it's just a poorly ground repair, then you could have someone grind it down properly so it doesn't catch the ball or ball/patch combo upon loading or shooting. It could of course be something entirely different, though (like the suggestion of it being a screw hole), which is why I suggest removing the barrel to look at it.

 

[zneufeld]

That's weird. It does look like it could be the top of that foremost pin peeking through into the bore, or a thin hump of metal from the bore itself that's been pushed upward by said pin. It could also be that upon initial assembly the pin hole was drilled too high, causing the pin to go through the bottom of the bore rather than under the barrel, and whoever put it together repaired the damage to the barrel before relocating the pin to a proper location and just didn't grind down the repair weld inside the bore.

If you feel comfortable doing so, I would suggest removing the tang bolt and the two barrel pins, then pulling the barrel and seeing what the underside of it looks like. It's really not a difficult process, you just have to have a tiny punch or other rigid object smaller than the pinholes and gently try pressing the pins out of place, so you don't break little chunks of wood out around the pinholes in the process. Try pushing them from both sides of the stock and see if they seem to want to come out easier from one side or the other, also.

If it does turn out to be the top of the pin coming through, or a thin skin of barrel steel being pushed up by the pin, then I'm not sure what to tell you. If it's just a poorly ground repair, then you could have someone grind it down properly so it doesn't catch the ball or ball/patch combo upon loading or shooting. It could of course be something entirely different, though (like the suggestion of it being a screw hole), which is why I suggest removing the barrel to look at it.

Hi Musketeer,

Thanks for the instruction on how to remove the barrel. That was going to be my next question, as I have never removed pins like this before (my other muzzleloader is a GPR with wedge pins).

I'll give that a try later today and report back.

 

[zneufeld]

The two barrel pins came out without much effort. The pin for the ramrod thimble was tougher, but came out with a minute of tapping.

I don't see any evidence of the pin pushing into the barrel.

I did discover that the thimble is broken where the pin goes through.

The raised spot almost aligns with the front lug (I think that's the correct term), but I can't tell if the lug has been repaired. It looks the same as the rear one.

 

[zneufeld]

Here's a better view of the underside of the barrel

Rear:

Front:

 

[Robby]

Hard to tell from the pictures but it appears to me the front lid is into the bore. I'd take a rod of a slightly smaller diameter, round off the leading edge a bit and gently tap it past the protuberance, and see what happens. That would determine my next move.
Robby

 

[Musketeer]

Interesting. Could be they got into the bore somehow while installing that front pin lug. I guess it's possible it's just something stuck in there at that point in the bore, but I can't imagine what it'd be.

 

[zneufeld]

Hard to tell from the pictures but it appears to me the front lid is into the bore. I'd take a rod of a slightly smaller diameter, round off the leading edge a bit and gently tap it past the protuberance, and see what happens. That would determine my next move.
Robby

Thanks, Robby. I'll try that. It hasn't responded at all to a few minutes of brushing and Scotchbrite, so whatever it is, it's hard!

 

[zneufeld]

Interesting. Could be they got into the bore somehow while installing that front pin lug. I guess it's possible it's just something stuck in there at that point in the bore, but I can't imagine what it'd be.

I asked TRS if they had any drawings of their Sea Service kit and told them about the mystery. They asked for more photos since they are curious now as well. I'll report back if they say anything interesting.

One of the mysteries is that their kit is .62, but this bore is definitely smaller. .61 RBs are far too large, and as close as I can tell, the bore is about 9/16ths. I don't have a micrometer, but I guess it's time to get one! Down the rabbit hole I go...

 

[hawkeye2]

It looks to me like the lugs were welded to the barrel and the welds ground down. That is a definite NO-NO and it's a wonder it didn't do more damage to the barrel. The welded area expands and then contracts as it cools. It contracts more than it expands which can distort the bore and leave "bumps" inside if it doesn't completely ruin the barrel. It can also introduce stresses that affect the barrel's performance as it warms up and cools while shooting. Once you have located the bump exactly that barrel can be saved by honing and/or lapping and I believe you'll find the hump is barrel metal displaced by shrinkage.

 

[zneufeld]

It looks to me like the lugs were welded to the barrel and the welds ground down. That is a definite NO-NO and it's a wonder it didn't do more damage to the barrel. The welded area expands and then contracts as it cools. It contracts more than it expands which can distort the bore and leave "bumps" inside if it doesn't completely ruin the barrel. It can also introduce stresses that affect the barrel's performance as it warms up and cools while shooting. Once you have located the bump exactly that barrel can be saved by honing and/or lapping and I believe you'll find the hump is barrel metal displaced by shrinkage.

Interesting. That deepens the mystery of where this barrel came from even further.

I need to learn to hone/lap anyway...I guess now is the time.

 

[Musketeer]

It looks to me like the lugs were welded to the barrel and the welds ground down.

It looks that way.

 

[M. De Land]

It's probably the screw holding the loading rod pipe pushing into the bore from to long a threaded hole.

Here's a better view of the underside of the barrel

View attachment 55461

Rear:
View attachment 55462

Front:
View attachment 55463

I see the trouble now, The lug has been welded on (Mig or Tig ) and the raised area in the barrel is distortion from the weld heat. Welding on any barrel is a no-no because it changes the metallurgy (strength) of the barrel in one spot. I would not fire it as it might or might not come apart , even with black powder pressure.

 

[Britsmoothy]

It definitely looks like complete penetration of a welding process.
I doubt it will compromise the barrel at all but just be an annoyance.

 

[M. De Land]

I see the trouble now, The lug has been welded on (Mig or Tig ) and the raised area in the barrel is distortion from the weld heat. Welding on any barrel is a no-no because it changes the metallurgy (strength) of the barrel in one spot. I would not fire it as it might or might not come apart , even with black powder pressure.

The lugs are best sweated on with the lugs having a big foot print fit to the barrel radius. Low temp silver solder will secure them for ever if done correctly with no chance of barrel metal damage. Most barrels are annealed (normalized ) before rifling to relieve stress. this generally happens in a temperature range of 1000- 1200 degrees. The Tig or Mig torch heats the steel to over 3000 F and usually leaves the steel brittle at the weld . If the barrel interior is not protected with anti scale compound then carbon cooks out leaving the surface scaled and or distorted (warped). This is what has occurred in your barrel. There very likely will be another raised area at the other lug weld.
It can be saved by clear boring and lining it to a smaller caliber so all is not lost. You won't need a very thick liner of modern barrel steel to make it safe to shoot.

 

[Britsmoothy]

The lugs are best sweated on with the lugs having a big foot print fit to the barrel radius. Low temp silver solder will secure them for ever if done correctly with no chance of barrel metal damage. Most barrels are annealed (normalized ) before rifling to relieve stress. this generally happens in a temperature range of 1000- 1200 degrees. The Tig or Mig torch heats the steel to over 3000 F and usually leaves the steel brittle at the weld . If the barrel interior is not protected with anti scale compound then carbon cooks out leaving the surface scaled and or distorted (warped). This is what has occurred in your barrel. There very likely will be another raised area at the other lug weld.
It can be saved by clear boring and lining it to a smaller caliber though so all is not lost. You won't need a very thick liner of modern barrel steel to make it safe to shoot.

It definitely should of had a heatsink the other side of the lug. Half round piece of copper wedges in place. Purged with argon would be good too.
Pulsed tig is good in these applications.. very low Hertz about 1.5. You can zap some amps in but give the parent material a break instead of a constant heating up and rapid cooling by constant plasma. Not many employ it though.

 

[Zonie]

zneufeld:

I wouldn't worry about the welding heat weakening the barrel but that internal bump will make loading the gun a pain.

I suggest taking the barrel to a good machine shop and asking them to ream the bore to remove the material that's causing the problem.

They should be able to use an adjustable reamer to do the job and it shouldn't cost too much. (That said, be sure to agree on a price before you give them the go ahead.)