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How to Do Fire Lapping on Barrels

Fire lapping is the process of firing projectiles with varying grits of lapping compound through the rifle's bore. The purpose is to gradually smooth and polish microscopic burrs, scratches and tooling marks left in the bore during the manufacturing process. A smooth bore contributes to longer barrel life, increased accuracy and reduced friction. A smooth bore is also easier to clean because copper and lead fouling is greatly reduced. Fire lapping is performed on a new, unfired barrel as part of the barrel break-in procedure.

Things You'll Need

Cleaning rod with correct-size jag
Cleaning patches
Bore mop
Bore solvent
JB bore cleaning compound
Fire lapping ammunition

Instructions

- 1
  Unload the rifle and retract the bolt to verify there is no live round in the chamber. Remove the bolt from the rifle.
- 2
  Fit a bore path in the jag's slot and dip the patch in bore solvent. Push the patch through the bore from the receiver end toward the muzzle. Repeat this procedure with a dry patch.
- 3
  Install the bore mop on the cleaning rod. Coat the bore mop with JB compound and swab the bore. This leaves a light coating of compound in the bore.
- 4
  Install the bolt in the rifle. Load the coarsest fire lapping ammunition in the rifle and shoot at your target.
- 5
  Repeat the previous steps until the finest grit ammunition has been fired through the bore.
- 6
  Clean the bore with solvent and patches one last time. Then run a dry patch through the bore. Finally, run one lightly oiled patch through the bore to prevent rust.

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