Gentlemen, good day. I wanted to use the knowledge of you all regarding Fire lapping. I have read several articles about it and have never gone through the process or met anyone personally who did it. It seems to be a method to remove imperfections from a barrel... in particular one that appears not be in good shape. I have been signed onto this site for only a few months and found some good information... all that said... I am just wondering you opinion of the process? if it is helpful? if it can cause more problems than cures? etc.
Thanks for any comments...
I have done some fire lapping in both percussion pistol and cartridge rifles. It works well in cartridge guns as the bullet only travels in one direction. I found in one of the rifles I did this to that the chamber throat was lengthened more than was change to boar diameter. It did to quite a good job of smoothing.
Fire lapping does not do much past about the lower third of the bore. It cuts quite aggressively at first but peters out pretty fast up bore.
I fire lapped a 58 Rem and ruined the forcing cone which had to be re-cut to restore accuracy.
I have hand lapped quite a few barrels with poured lead laps and especially made lapping rods with bearing handles. This is the very best method as one has much more control over the cutting action.
Revolver barrels are best lapped while still in the frame as the thread pressure tends to choke the bore a bit in that part of the barrel.
A muzzle loading rifle barrel should have the breech plug removed and lapped from breech to muzzle.
A freshly charged lap should not be introduced into the muzzle but rather the breech as it cuts most aggressively at the very beginning.
Cartridge barrels can just as easily be lapped as muzzle loading barrels as I have done a fair number of both personally.
Far as I can tell a level boar will shoot just as well as will a bore with a bit of taper lapped in.
Some of the old time muzzle loading match barrel makers ( Warner and Brockway to name a couple) experimented extensively with gain twist and taper choking. They both settled on level bores with a bit of choke in the last few inches at the muzzle with even twist rifling.
The choke is lapped in and is only a few ten thousands.