Muzzleloader bore uniformity

[Hannibal]

I've got a new Pendersoli flintlock kit on the way so I'm looking forward to a new to me shooting experience. It's a 32 caliber and I'd thought I may do some small game hunting with it, so I'd like to wring all the accuracy possible from it. I've run into problems with barrels before on other rifles where there were constrictions in the bore where dovetails and stampings are located. Obviously slugging the bore is necessary to find such problems and I was curious if many of you check your bores and if constrictions are rare or commonplace, particularly in barrels from Pendersoli?

Thanks for looking.

[NSB]

Pedersoli makes some truly outstanding quality barrels. They’re as good as anybody’s. That being said, you can get a constriction in anyone’s barrel. Be prepared to look for one and then get out the bore paste and get to work if you find one. Often, they don’t effect accuracy. My experience with half a dozen Pedersoli rifles has been fantastic. All were very, very accurate shooters.

[Hannibal]

Good to know. Thanks.

[LAGS]

I found a couple of barrels that had minor restrictions or constrictions.
If I felt it would be an issue , I made an epoxy Lapping tool molded to the barrel.
Then lapped out the constriction with the molded slug on a cleaning rod.
Some were centerfire rifle barrels too.
So these issues don't just pertain to BP guns.
But BP barrels are also a lot more forgiving with the patch around a round ball.

[Hannibal]

The particular rifle I found the most problems in was a Henry in .357, somewhere around 2010 production. It had accuracy problems and there were 4 constricted spots. 2 at the sight dovetails, one at the stamping location and one in about the middle for no obvious reason.
I lapped it and it helped a lot but never was a bughole shooter. It wound up holding 4" @100 yds with jacketed bullets but I never tried to get a cast bullet to shoot. Ultimately I decided it was too heavy and flashy with the brass receiver and sold it. I thought it shot pretty well for a lever action with pistol bullets.

Anyway, I just wondered if it was common or not to find this in muzzleloader barrels.

[HWooldridge]

I would say "no" to whether it's common in muzzleloader tubes, predominately because ML barrels are generally thicker walled than smokeless.

The worst marks I have ever seen were roll stamps in 44 cal carbine barrels, which have fairly thin walls. I've seen 3 instances over the years, all 44 bore, where an impression could clearly be seen inside the barrel as a series of dents. One was a Ruger and two were Winchester barrels. One of the Winchester barrels would not shoot worth a damn - 3-4" at 50 yards was the best it would do with a jacketed pill.

A machined dovetail shouldn't leave an impression if clear cut with a mill - although any type of mechanical stress might be enough to collapse into the bore.

[Hannibal]

Right. I never understood how that particular barrel wound up like that either. Henry Big Boys with the brass receiver have heavy barrels and particularly the .357s I guess the dovetails must be cut in a press of some type using stepped cutters and stamped while the barrel is still really hot? Then maybe the construction in the middle of the barrel was from the holding fixture? I've no idea how they are made so this is all just wild guessing.

[HWooldridge]

Right. I never understood how that particular barrel wound up like that either. Henry Big Boys with the brass receiver have heavy barrels and particularly the .357s I guess the dovetails must be cut in a press of some type using stepped cutters and stamped while the barrel is still really hot? Then maybe the construction in the middle of the barrel was from the holding fixture? I've no idea how they are made so this is all just wild guessing.

None of that work would be done hot but they might be broaching the dovetails for the sake of speed and that process could be causing a mark - or the actual sight may be such a tight fit that it's causing distortion. Roll marks are done under mechanical or hydraulic force - and it's easy to get too much of a good thing. I can see a technician continuing to increase pressure rather than change out the roll dies when the tools start to dull.

[LAGS]

Funny you mentioned a Henry .357.
That was the worst barrel I have had with tight spots down the bore.
But they lapped out fine.
But accuracy was pretty good after lapping.
But that was with Cast Slugs and worked up loads.
That one is my wife's rifle.
I bought it for her , because she wanted my .357 Marlin.
And I wasn't giving that one up.