How do you tell if rifling is good?

[LonesomePigeon]

How do you tell if the rifling is good on a new gun? I've heard that with the cap n ball repros sometimes the rifling will be uneven, ie deeper or shallower on one side than the other, or there can be spots that require "lapping". I suspect the answer is it's just a skill you develop after looking at a lot of barrels but if there are any tips or techniques please tell.

[Lefty Dude]

If the reference is Cap & ball repo's, well for the price we pay ya take your chances. I have some pietta's that are good, and some not so good. However a little JB bore paste and tight patches can do wonders to burnish a bore.
I burnish all my Fire Arms that shoot lead with JB's.

[Kent Shootwell]

In guns that have a open breech visually inspect a bore in good light looking for any scratches, odd grooves or machine marks. Next tap a lead ball into the well oiled bore and push it threw slowly, you'll feel tight and loose spots. Look the muzzle over for sharp edges, burrs and any unevenness. The more barrels you look at the better you get at spotting things. You'll also find that a bore need not be a perfect mirror to shoot well but the best ones are smooth and even and will be easier to clean. Truelly lapping a barrel is a skill but as Lefty Dude points out a serious cleaning can help out.

[LonesomePigeon]

Thanks those are some good tips.

[Flint]

Some years ago I had an Italian made SAA which had been rifled, apparently, without a pilot on the tool, as there was only rifling on one side of the bore...  A new barrel fixed the problem.  The off center barrel grouped in a different places at different ranges.

[Lefty Dude]

My Brother bought a new Marlin 94 in 41 mag.. The piece would not group or shoot well for accuracy at all. He finally slug the bore, only to find the factory fitted a 45 cal barrel on the piece and chambered it for 41 cal. Sent it to Marlin for a new barrel, when the piece returned it would not feed properly, they installed a 45 carrier in the piece. Sent it to Marlin again. When he finally got the piece correct he sold it. Then bought a 45CS Marlin 94, which is a lovely piece he still owns.

[Noz]

Marlin's customer service, in the best of times, left a lot to be desired.
I had the same gun, an 1894FG(41 mag) that had the worst "dreaded Marlin jam" ever seen. I sent it tiMarlin with detailed description of the problem 3 times and received the untouched gun back each time with the statement that "it was within specs". They included each time a new carrier. I wound up with a nice rifle that would not feed with any of the 4 carriers.
I took it to an amateur welder and he laid a bead along the bottom of the carrier, I smoothed it down, re-installed it and it hasn't misfed since.

[Coffinmaker]

Hi LP,
Don't look now, but what you have heard about the bore rifling in Cap Guns is about half true.  Once in a while you'll get a "Thursday"
gun.  Not really all that common.  You'll also find the same problem(s) in ALL the Manufacturers.
Seriously, myself, when I get a new Cap Gun out of the box, I look down the bore.  If there are lands and grooves, I'm good.  The only other time I'll be looking down there is when I clean the gun after a match or trip to the range.  Same always applied to my Customer's
guns.  Look down the bore .... yup, lands and grooves, it's good.  It's not something we can "fix" anyway.  Now, if there are no sands nor grooves, new barrel time.

Coffinmaker

[Flatbush]

I bought a new pair of colt clones with normal looking rifling, but the forcing cones looked like they had been chewed out by angry beavers instead of skilled machinists. I was afraid I would get a lot of lead buildup there, but after a season's worth of shooting, it hasn't been an issue.

[Coffinmaker]

Gad Zooks but I hate the term "Clone."  (shut up and get off the soap box).
Flatbush,
Good that you have had luck with those krappy forcing cones.  Clean em up anyway.  I would suggest 11 degrees as a good start for smooth bullet transition from cylinder to bore.

Coffinmaker