M1865 Burnside Spencer carbine

Norman74N · August 29, 2026, 01:57:07 PM

Getting this original gun to shoot. Black powder only of course. Have installed a center fire conversion block; works well. My question is: the barrel is very pitted inside I have borescope it and the magnification makes it look pretty bad. The barrel wall thickness is about 3 mm. My question is how much pitting makes it unsafe to shoot. I don't care about accuracy at this point. Thanks.

Trailrider · August 29, 2026, 03:11:43 PM

For one thing, have you tried cleaning the bore? Sometimes what looks like bad pitting is leading that can be cleaned out. Even if there is considerable pitting left, the thing to do is load a round with BP, tie the carbine to a rest, and pull the trigger with a string. If it doesn't blow, chances are that with BP it will stay together. Of course, due to its age, you never know.

Norman74N · September 01, 2026, 12:00:30 AM

Thank you for the help. Yes, I spent hours cleaning the bore. I've used several of the best cleaners available, etc.. I will fasten the gun down to a wooden rest that I made, and I will screw the rest of the table and sandbag the gun to the rest and pull it with a 25 foot length of twine with a face shield, leather coat and gloves on I will likely use 32.5 grains of Swiss 2FG powder. That is, black powder. I feel quite certain that it will be OK. Right now I am trying to get the bullets to transition smoothly from the buttock magazine to the breach block. This is a long story in itself.

Norman74N · September 03, 2026, 03:32:31 PM

I fired the Spencer M1865 Burnside built yesterday. Went well with no misfires in twenty rounds. Gun was very inaccurate at 50 yds with 36 grains of Swiss 2Fg. Lyman 350 grain bullet SPG, sized to .510 20:1 lead:tin leg pistol primer, annealed cases,etc. Still not fluid with cycling bullets from magazine tube. Harder lead here doesn't help, increase OAL from 1.5" to 1.6" helped maybe. Not sure which is worse: the inaccuracy of the gun or the lack of bullets cycling smoothly from magazine to chamber, where the lead of the Ogive gets gouged and tattered.... It is quite an interesting challenge, however as the mechanism is so complicated.

DJ · September 04, 2026, 08:58:43 AM

.510 bullet diameter sounds a little small--have you slugged the bore?

wildman1 · September 05, 2026, 07:53:59 AM

I have improved the accuracy of several rifles that were very pitted. This was done by fire lapping, my worst was a 25-35 that would not shoot under 6" at 50 yds. When I finished it would shoot just over 2" at 200 yds. This MUST be done with the proper materials and according to the instructions provided. I ordered the kit from NECO industries. The bore remains pitted after this but is very polished.
wM1

John Jamieson · September 07, 2026, 07:08:26 PM

.510 sounds really small. Try posting down on the spencer forum too.

Sedalia Dave · September 13, 2026, 07:58:31 AM

Quote from: Norman74N on September 03, 2026, 03:32:31 PMI fired the Spencer M1865 Burnside built yesterday. Went well with no misfires in twenty rounds. Gun was very inaccurate at 50 yds with 36 grains of Swiss 2Fg. Lyman 350 grain bullet SPG, sized to .510 20:1 lead:tin leg pistol primer, annealed cases,etc. Still not fluid with cycling bullets from magazine tube. Harder lead here doesn't help, increase OAL from 1.5" to 1.6" helped maybe. Not sure which is worse: the inaccuracy of the gun or the lack of bullets cycling smoothly from magazine to chamber, where the lead of the Ogive gets gouged and tattered.... It is quite an interesting challenge, however as the mechanism is so complicated.

Change OAL in 0.010" increments between 1.500" and 1.600". Spencers are very sensitive to OAL.
How you cycle the action matters as well. Needs to be a firm fluid motion.

Sedalia Dave · September 13, 2026, 08:08:30 AM

You should have this post moved to the Spencer Shooting Society thread. Lots of knowledge there.