Barrel Polishing Question?

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Painterman

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Sep 2, 2022
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Indianapolis, In. Marion
I have a .22 Avenger barrel that is very rough where the rifling begins at the breach. I did polish and recrown and pushed several pellets by hand, the first 2.5 inches of the rifling are rather tight as well. I polished with a bore mop and JB and put a lot of extra effort in the tight spot including using a drill (with mop).
I'm thinking of using the back end of a drill bit, grinding a taper and polishing like a recrown. I'm not to concerned about being tight at the breach but this sharp edge must go.
Thanks in advance for any help.

Painterman... aka David from Indy
 
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NOT...a good idea to "spin" the mop !!!
Youll screw up that rifling where the mop has been rotating for any length of time. It will leave a rounded edge on one side of the land, and a sharp edge on the other...right ?

Just use an in and out motion on the rifling.

You can use a drill on the lead, "before" the rifling. If you want to smooth that area, yes, a rotation action is fine, again, just "don't go into the rifling.

Mike
 
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To break the sharp leading edge of the rifling, I like using a rubberized abrasive bit similar to this
https://www.amazon.com/Polishing-Cylinder-Mounted-Electric-Accessories/dp/B08HPCN69N

It can also be done by wet sanding with a regimen of 400 -> 600 -> 1200 grit wrapped around a dowel or pin. Wrap it so the paper overlaps the end of the pin, and work the sharp edge with an in-and-out motion all around the circumference. You should be able to feel as the sharp edge wears down.

If you decide to tackle the tight region, that is the realm of a cast lap and a fairly aggressive abrasive. An aluminum oxide / grease slurry starting no finer than 180-220 grit.
 
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nervoustrig said:
To break the sharp leading edge of the rifling, I like using a rubberized abrasive bit similar to this
https://www.amazon.com/Polishing-Cylinder-Mounted-Electric-Accessories/dp/B08HPCN69N

It can also be done by wet sanding with a regimen of 400 -> 600 -> 1200 grit wrapped around a dowel or pin. Wrap it so the paper overlaps the end of the pin, and work the sharp edge with an in-and-out motion all around the circumference. You should be able to feel as the sharp edge wears down.

If you decide to tackle the tight region, that is the realm of a cast lap and a fairly aggressive abrasive. An aluminum oxide / grease slurry starting no finer than 180-220 grit.
Click to expand...
I think that any hobbyist who undertakes a lead lapping process should have an extra barrel on hand. Consider it an educational expense.
 
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Painterman said:
I have a .22 Avenger barrel that is very rough where the rifling begins at the breach. I did polish and recrown and pushed several pellets by hand, the first 2.5 inches of the rifling are rather tight as well. I polished with a bore mop and JB and put a lot of extra effort in the tight spot including using a drill (with mop).
I'm thinking of using the back end of a drill bit, grinding a taper and polishing like a recrown. I'm not to concerned about being tight at the breach but this sharp edge must go.
Thanks in advance for any help.

Painterman... aka David from Indy
Click to expand...

Um, put that stuff down and back up slowly!

Sorry, everything you did was wrong and I'll bet that JB on drill did some damage.

First, you need to pull the barrel and look inside the breech where the pellets load, see if you really have a burr or rough spot or if the bore is fine and your ammo is too big.

I lapp and polish bores for a fee and have some proprietary items I use to smooth bores without damage but you need to do some reading, study up and get some supplies. For one, bore mops are much too loose in the bore to do any good in burr removal, you need a very tight patch but because you need to understand the mechanics of them first, I do not recommend the use of cleaning rods.
 
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crazyhorse said:
Just fire lap the barrel...but the breech must be by hand.
Click to expand...

For the love of God, please dont. The material that airguns are made from is much too soft and the score lines made by the grit will be impossible to polish out.

Airgun barrels should be hand lapped with fine grit compounds and only with tight fitting patches.
 
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nervoustrig said:
To break the sharp leading edge of the rifling, I like using a rubberized abrasive bit similar to this
https://www.amazon.com/Polishing-Cylinder-Mounted-Electric-Accessories/dp/B08HPCN69N

It can also be done by wet sanding with a regimen of 400 -> 600 -> 1200 grit wrapped around a dowel or pin. Wrap it so the paper overlaps the end of the pin, and work the sharp edge with an in-and-out motion all around the circumference. You should be able to feel as the sharp edge wears down.

If you decide to tackle the tight region, that is the realm of a cast lap and a fairly aggressive abrasive. An aluminum oxide / grease slurry starting no finer than 180-220 grit.
Click to expand...

This is smith level stuff, noobs take this WAY too far and destroy barrels. Imagine 400 grit fresh off the sheet that hasn't been broken yet in a fresh 25C barrel?
 
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Firewalker said:
This is smith level stuff, noobs take this WAY too far and destroy barrels. Imagine 400 grit fresh off the sheet that hasn't been broken yet in a fresh 25C barrel?
Click to expand...
I agree, smith-level stuff. The prospect of removing a described 2.5” long tight section calls for a cast lap, and a cast lap is the domain of a smith or at least an experienced hobbyist. The tools to do it—heating and melting tools, lapping fixture, ball-bearing rod, guide bushings, abrasives, etc.—pretty well discourage the casual hobbyist.

Regarding the choice of abrasive, we don’t know in this particular case how much material would need to be removed to bring the bore into good uniformity but my experience has been that a tight spot which can be easily felt with patches or by pushing pellets through…it’s something that would be an exercise in frustration to lap out with 400 grit. As in multiple, multiple hours of forearm-burning exercise. With J-B? Practically impossible.
 
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nervoustrig said:
I agree, smith-level stuff. The prospect of removing a described 2.5” long tight section calls for a cast lap, and a cast lap is the domain of a smith or at least an experienced hobbyist. The tools to do it—heating and melting tools, lapping fixture, ball-bearing rod, guide bushings, abrasives, etc.—pretty well discourage the casual hobbyist.

Regarding the choice of abrasive, we don’t know in this particular case how much material would need to be removed to bring the bore into good uniformity but my experience has been that a tight spot which can be easily felt with patches or by pushing pellets through…it’s something that would be an exercise in frustration to lap out with 400 grit. As in multiple, multiple hours of forearm-burning exercise. With J-B? Practically impossible.
Click to expand...

"IF" it's an actual tight spot?

Funny thing about lead, by the time it gets pushed down a couple inches of rough barrel, it stops being really tight as it sluffs off, especially dead soft lead we use in airguns.
 
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Firewalker said:
Um, put that stuff down and back up slowly!

Sorry, everything you did was wrong and I'll bet that JB on drill did some damage.

First, you need to pull the barrel and look inside the breech where the pellets load, see if you really have a burr or rough spot or if the bore is fine and your ammo is too big.

I lapp and polish bores for a fee and have some proprietary items I use to smooth bores without damage but you need to do some reading, study up and get some supplies. For one, bore mops are much too loose in the bore to do any good in burr removal, you need a very tight patch but because you need to understand the mechanics of them first, I do not recommend the use of cleaning rods.
Click to expand...
The JB with the drill was very little only within those first two inches. When inspecting in the sun I found no swirls or scratches, all of the rifling looks fine.
 
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Painterman said:
I have a .22 Avenger barrel that is very rough where the rifling begins at the breach. I did polish and recrown and pushed several pellets by hand, the first 2.5 inches of the rifling are rather tight as well. I polished with a bore mop and JB and put a lot of extra effort in the tight spot including using a drill (with mop).
I'm thinking of using the back end of a drill bit, grinding a taper and polishing like a recrown. I'm not to concerned about being tight at the breach but this sharp edge must go.
Thanks in advance for any help.

Painterman... aka David from Indy
Click to expand...
Buffing compound on felt cleaning pellets, in n out , in n out , like 100 times.
 
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I have actually formed cratex bits into reamers for leades that came out beautiful. I put a drill in a vice, put the bit in the drill and use a file to slowly work down the bit to the size and taper I want and then use it in the barrel, carefully. The cratex bits come in many different grits and shapes. You can find them on Amazon. This has to be done really patiently, and has mechanically fixed has you can, but it can work great if you take your time. Setup is everything, actual work time on the barrel is very short. Anything past the leade itself is not for these bits. I haven't tackled anything down barrel as severe as your problem but I would listen to Motorhead and Nervoustrig advice real closely.
 
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