hand lapping a barrel

[Brians356]

A 9 year old thread.

When our Admin starts locking stale threads, I'll stop commenting in them. Fair enough?
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[butchlambert]

When our Admin starts locking stale threads, I'll stop commenting in them. Fair enough?
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Sir, it doesn't bother me, just alerting folks about a dead thread. If you can add anything to I'll read it.

 

[Brians356]

Sir, it doesn't bother me, just alerting folks about a dead thread. If you can add anything to I'll read it.

I should have refrained, you certainly didn't come on as being miffed. I guess I'm a little jumpy, as there are so many self-appointed ill-mannered thread police, mostly on other forums.
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[mchees1]

Fire lapping is easy and works. I fire lapped a Savage .308 barrel and accuracy and ease of cleaning improved. HOWEVER, it did chase the lands a long way down the barrel - about 0.110". So now if I want to improve a barrel, I don't use the entire set of Tubb abrasive bullets, I just use the Wheeler lapping grit kit and make my own abrasive bullets. I select whatever grit I want to use, put some on a small steel plate, place the bullet in the paste, then use another steel plate on top and press and roll the plates back-and-forth to force the grit into the bullet. Then load starting loads and shoot. Thoroughly clean barrel and check for progress. I made 5 bullets using 600 grit and used them on a Ruger Precision 6mm Creedmoor barrel. It helped a little and didn't remove a lot of material or chase the lands much at all (lands moved about 0.005"). I have pictures of the before and after of the same land as an illustration.

 

[Brians356]

Fire lapping is easy and works. I fire lapped a Savage .308 barrel and accuracy and ease of cleaning improved. HOWEVER, it did chase the lands a long way down the barrel - about 0.110". So now if I want to improve a barrel, I don't use the entire set of Tubb abrasive bullets, I just use the Wheeler lapping grit kit and make my own abrasive bullets. I select whatever grit I want to use, put some on a small steel plate, place the bullet in the paste, then use another steel plate on top and press and roll the plates back-and-forth to force the grit into the bullet. Then load starting loads and shoot. Thoroughly clean barrel and check for progress. I made 5 bullets using 600 grit and used them on a Ruger Precision 6mm Creedmoor barrel. It helped a little and didn't remove a lot of material or chase the lands much at all (lands moved about 0.005"). I have pictures of the before and after of the same land as an illustration.

How was cleaning out copper affected?

I've Tubbed three hunting rifles, so far all showed significant accuracy improvement and less copper fouling (and easier to clean.) But yes, the lands advanced significantly, not surprisingly considering the severity of fire cracking.
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[mchees1]

How was cleaning out copper affected?

I've Tubbed three hunting rifles, so far all showed significant accuracy improvement and less copper fouling (and easier to clean.) But yes, the lands advanced significantly, not surprisingly considering the severity of fire cracking.
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After the fire lapping, there was less copper fouling and the barrel cleaned up faster and easier. I have had great success with KG12 copper remover. Non ammonia and works quickly.

 

[Will Henry]

I started hand lapping barrels about fifty years ago based on instructions given in Ned Roberts' book, "The Muzzleloading Caplock Rifle". I modified my technique over the years to better fit the barrel being lapped and to accomplish what I intended in the barrel. I never used anything finer than a 400 grit and usually used 280 grit Clover compound which would break down fairly quickly anyway.
In most cases, lapping was intended to simply achieve a desired surface finish in the barrel but frequently, it was neccessary to alter dimensions as well (remove tight spots or produce a barrel with some choke). If a lot material had to be removed (.001" or more) diamond dust cut fast and didn't break down.
Lapping is a tedious operation at best. The casting of the lap is sometimes not as easy as it should be. This is especially true with smaller calibers and I hate doing 22's. Swaging a lead lap in the bore can work out real well in many cases. This is sort of what you are doing when you bump the lap up to keep it tight anyway.
I always considered firelapping to be a half assed way of doing things but there is no question it can work well and it is comparatively easy to do. WH

 

[msalm]

This discussion brought up an idea/question in my mind....I wonder if...for initial barrel break in....two to five rounds of Tubb's final finish bullets wouldn't just work slick as heck to break in the throat of a freshly chambered barrel.....

Wonder if anyone would have the guts to try it with a $325 high end barrel blank and a chamber job. I can just hear the gunsmith yelling.. "YOU DID WHAT??????!!!!!"

 

[butchlambert]

This discussion brought up an idea/question in my mind....I wonder if...for initial barrel break in....two to five rounds of Tubb's final finish bullets wouldn't just work slick as heck to break in the throat of a freshly chambered barrel.....

Yes, about .050" worth.

 

[msalm]

Yes, about .050" worth.

So have the gunsmith chamber with a shorter f.b. than wanted? I’m only half joking I suppose, it may be a quick break in that would work but so much for knowing exactly what the potential was before and after.

 

[Brians356]

Yes, about .050" worth.

That's an exaggeration probably. I've run a complete progressive set of 50 Tubb bullets through three old barrels and only seen about .010" of extension.
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[Someoldguy]

I'm going to go out on a limb here, but I'm thinking as long as shooting sports have been around and as quick and easy as firelapping is compared with other alternatives that if there was any real merit to it the practice would have become an adopted standard a long while ago.

But if you like it, by all means have right at it.

 

[butchlambert]

That's an exaggeration probably. I've run a complete progressive set of 50 Tubb bullets through three old barrels and only seen about .010" of extension.
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OK Brian, I'm sure glad that you are happy. By the way, how did you measure that?

 

[Brians356]

OK Brian, I'm sure glad that you are happy. By the way, how did you measure that?

I didn't say I was happy (or unhappy) not that it's relevant here anyway. I measured the change in "length to touching lands" using a Stoney Point OAL gauge and bullet comparator.
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[butchlambert]

I didn't say I was happy (or unhappy) not that it's relevant here anyway. I measured the change in "length to touching lands" using a Stoney Point OAL gauge and bullet comparator.
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Now I understand only .010!

 

[msalm]

I'm going to go out on a limb here, but I'm thinking as long as shooting sports have been around and as quick and easy as firelapping is compared with other alternatives that if there was any real merit to it the practice would have become an adopted standard a long while ago.

But if you like it, by all means have right at it.

I don’t know, have you ever heard of anyone trying it with a new barrel install? I’ve read of a tight patch with JB, a ‘bob’ to polish the throat after the chambering/throating, the whole shoot one, clean, etc,,,. Have read about abrasive loaded lead bullets to break in a revolver and get rid of tight cylinder throats and tenon constriction....

I’m really not arguing that it IS a great method, but I am curious. I have two rifles I recently built, a 32” 284 Fclasser and a 26” 22 Creedmoor for a LR coyote rifle...I might be curious enough to try it with 2-5 bullets each and see how the throat looks. I do think it’s a fairly low risk endeavor.

 

[Dusty Stevens]

I cant bring myself to firing lapping compound down a barrel even if it was the last shots on a wore out barrel thats getting pulled off

 

[Someoldguy]

I don’t know, have you ever heard of anyone trying it with a new barrel install? I’ve read of a tight patch with JB, a ‘bob’ to polish the throat after the chambering/throating, the whole shoot one, clean, etc,,,. Have read about abrasive loaded lead bullets to break in a revolver and get rid of tight cylinder throats and tenon constriction....

I’m really not arguing that it IS a great method, but I am curious. I have two rifles I recently built, a 32” 284 Fclasser and a 26” 22 Creedmoor for a LR coyote rifle...I might be curious enough to try it with 2-5 bullets each and see how the throat looks. I do think it’s a fairly low risk endeavor.

I'd only try it if the doggone thing wouldn't shoot. And then after paying for a premium blank and a chambering job you can bet you're backside I'd want to know why fire lapping was necessary .

 

[msinc]

I cant bring myself to firing lapping compound down a barrel even if it was the last shots on a wore out barrel thats getting pulled off

I've never done it. But, I have a good buddy that just got a factory 243. He has had bad luck and a lot of trouble getting a 243 that will shoot. He got a Weatherby Vanguard in 243 because the last three rifles he "acquired" were all Weatherby's and they all shot fantastic, so I guess he figured it was worth a try. Well, we all have our "caliber nemesis" and his seems to be the 243 win.
At this point he figures "what is there to loose" and gets a fire lapping kit. He does exactly as the instructions say and as skeptical as I am, I have to say it worked and worked damn good. This thing went from 2" groups at best to 3/4" at 100 and it quit copper fouling. He didn't do anything else to the rifle, no trigger or adjustment, no glass bedding, no anything, just getting the copper out and the fire lap, so I'd say when you are down to nothing left to loose...why not???