Barrel Break In

Break-in

The basic principle behind breaking-in a barrel is to use the bullets to smooth out imperfections as they travel down the bore. The mechanics are simple; you want the bullet to ride on the bare metal of the bore so that it will wear on the high spots. As the bullet passes the high spots it will also leave some jacket fouling. If there is sufficient jacket fouling on the high spot, the next bullet will be riding on the fouling rather than wearing on the barrel. So, we want to clean all the fouling out of the barrel before the next bullet is fired.

Break-in is not the same as fire-lapping. Fire-lapping uses low-velocity loads and special abrasives. Break-in uses standard jacketed bullets at standard velocities.

You’ll hear all sorts of patterns of firing and cleaning for barrel break-ins but there isn’t a magic number. When customers insisted on having me break-in a barrel for them (as opposed to lapping or replacing with a premium barrel) I’d clean the bore to the bare metal and fire a test group. Next, I’d clean the bore back to the bare metal, fire a single round, and clean back to the bare metal. I’d repeat the single shots for five or ten shots depending how the fouling looked. A drastic decrease in the fouling for each shot told me I was about finished. Then I’d fire a few groups of three to five shots cleaning between each group. There was seldom a dramatic decrease in group size but improvements varied with the individual barrels.

Breaking-in a premium barrel is usually a waste of time as the barrel makers lap the bores to a fine finish.

For cleaning you may want to use a fairly aggressive copper solvent. Do not leave aggressive solvents in the bore for any length of time. Do not mix solvents. If you want to switch solvents, make certain you have all traces of the old solvent out of the bore before you use the new one. The Outer’s Foul-Out is another good system.

Breaking-in a barrel is pointless if you wind up doing more damage with the cleaning. Don’t let your cleaning rod rub on the crown or the throat, or flex against the side of the bore. If cleaning from the muzzle, use a muzzle guide to protect the crown. If cleaning from the breach, use a chamber guide to protect the throat. Don’t use brushes or patches that are so tight they cause the cleaning rod to flex and rub inside the bore. Consider pulling the cleaning rod through the bore rather than pushing it, to prevent flexing. The only real disadvantage to cleaning from muzzle to breach is you wind up pushing solvent and dirt into the chamber and action. The only cleaning rod material I don’t recommend is aluminum as the surface is the extremely hard aluminum oxide- like on sandpaper.