Handlapping

Question:
Mr. Bellm, I just finished reading your article about fire lapping barrels. Since fire lapping will cause accelerated wear in the throat area, I was wondering about hand lapping. Would the gains made be any different than fire lapping, and will the throat erosion be on the same scale? If hand lapping is OK, how would you go about it? I have problems with copper fouling in a couple of guns, and would like to see if this will help.
 

Thank you,
Charlie Baker

 

Answer:
There are a lot of things done with good effect that really should not be done. Every so often I hear of someone using a tight patch on a cleaning rod and valve grinding compound to smooth things up.

However, every place the cleaning rod contacts inside the barrel, the rod itself will be lapping away material. Assuming you are working from the breech end, first point of contact between the rod and the bore is the throat, ie., where the rifling start. Firelapping removes material in a pretty uniform manner around the circumference of the bore and grooves, but the rod will be cutting away on the delicate ends of the rifling in a very irregular manner. I would not do it. Will there be someone who will jump up and swear by the process? Probably, but he is good business for the barrel makers.

If you could control the alignment of the lap precisely with the throat, hand lapping would have the potential of not opening the throat diameter as much as fire lapping, but how are you going to accomplish this?

My opinion is that no lapping whatever should be done to a chambered barrel unless the throat will be cut out by rechambering and a new throat cut. And I feel the same way about the crown. Nothing should go back in it like a hand lap or a barrel spinner once it is cut.

However, I will add that one of the barrels I lapped recently had a Muzzle Tamer factory brake on it and some really nasty burrs and dings rolled to the inside of the barrel at the crown inside the brake. I was about to "bag it" on that one and contact the owner regarding re-crowning it, but went ahead and fire lapped the barrel. Edge of the crown cut was still a bit irregular, BUT the fire lapping cleaned the burrs and dings out of the inside of the barrel very nicely, enough so that I felt pretty good about the crown after the fire lapping was done.

A new lapped Hart benchrest blank will copper foul. Fire-lapped barrels copper foul. It is the heavy, irregular build up of copper that is a problem. Do a normal amount of cleaning, shoot it, and eventually it will smooth up. I'd do as much cleaning by soaking as possible and pass the cleaning rod through the barrel as little as possible.

In principle, I do not like adding abrasive of any kind to a cleaning rod.... or a dirty cleaning rod. Dirt and grit cut metal. Period. Coated rods and hard steel rods do less damage, true, but anything gritty passing over metal under some degree of pressure is going to cut something. For this reason, I have never brought myself to use JB Bore cleaner, the abrasive type, though many swear by it. I'll hold off passing any further judgment until I spend some time with it and the bore scope to see what is actually happening. I don't think I'd use anything on a cleaning rod more aggressive than JB.

For subjects like this, it would be good for us to have our own forum, since I am sure your question would draw many opposing comments.

In parting, let me remind you that I don't think I have ever seen Don Bower clean a barrel at the range. He goes out and shoots and shoots and shoots. Good idea? Or bad idea? Nonetheless, he and his students shoot some mighty impressive groups way, way far out there.

Opposing ideas are welcome, but those that can be substantiated with the bore scope are the ones of substance we need to look at.

All the best,
Mike Bellm

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