Firelapping, holy crap it works or how I saved $300

[butchlambert]

Years ago, I cast my own 22 caliber bullets to fire lap Rem 700 factory barrels with pure linotype. You can roll the bullets in between two steel plates with the grit you like, bullets have to be sized of course.

I worked up a load with 700X going 1000 fps in 223 and 22/250 barrels.

I ruined the first barrel by firing Ten 600 grit rounds down the barrel. From then on, I used two 600 grit, then up to 10 of the 800 grit rounds followed by 1200 grit rounds. You could feel the barrel getting smoother with a very tight punch type jag/patch.

With my very little experience back then, it was obvious that throats were walking out in a big hurry and bore dia was changing due to velocity dropping.

I made the decision that time invested was not worth it for me....in spades.

At this time, it maybe worth the effort to fire lap some 1200 grit on barrels with heavy fire cracking to smooth the tops of the fire cracks that are curling up, but you know going into it that your efforts are more for fun of "playing". You can know for a fact that the throat dia is much larger that it was when it was new.

A replacement barrel should have already been ordered.

I fire lapped a bunch of 22 Rim fires that I had with great success with all but one Ruger target pistol that I absolutely ruined. I used nothing but Standard velocity cci with 800 grit and 1200 grit. If you go down this road, pick out a "sacrificial lamb" for your learning curve.

Casting a lap would be the way to go, but this does not appeal to many as it is is very labor intensive compared to just sticking bullets in a chamber and pulling the trigger.

Tubb has done extensive testing with fire lapping, his method would be something to investigate. Nathan Foster, the famous goat shooter in New Zealand, has done extensive testing on his big 7mm to smooth out the curls on the fire cracking with good success also. Both Tubb and Foster are dealing with a different issue of fire cracking from extensive shooting, while the OP is dealing with drill marks in a barrel from manufacture.

It is a Hail Mary attempt to try and smooth out the drill marks as there are likely other issues with the barrel as well, but it is fun to play in this hobby.

You do know that the custom barrel builders use about 320 for lapping. You can get too smooth of a finish.

 

[AckleymanII]

Yes, I know. I lapped a 9 groove experimental Pac Nor barrel so smooth that it was gold plated in 60 rounds, solid brass coated barrel from bullet jackets.

It is a catch 22 on fire lapping with bullets at my level of the learning curve. I would defer to those that know a lot more than I do on this subject.

Nathan Hale and Tubb fire lap barrels that are fire cracked badly to keep them shooting. Next time I get one in badly fire cracked shape, I may play with one or both of their methods. Tubbs is a pretty sharp guy from what I have read, and I don't think that he lends much to selling Snake Oil.

 

[rogina]

You do know that the custom barrel builders use about 320 for lapping. You can get too smooth of a finish.

Butch, I may be wrong, but I think the 320 keeps breaking down to smaller as it is used.

 

[butchlambert]

Butch, I may be wrong, but I think the 320 keeps breaking down to smaller as it is used.

If you go to a barrel maker's shop You will change your mind. The grit in the lapping compound is harder than the steel.