lapping a barel
- Thread starter rebs
- Start date
I've never painted a car or lapped a barrel. I have rebuilt some transmissions, which was easy.(with all the tools)...
DShortt
Gold $$ Contributor
I tried it once on a barrel with multiple constrictions. It was bad enough I knew that even if I made it worse there was little to lose anyway.
I found it to be tedious and quite time consuming. I did manage to improve the accuracy considerably but needless to say I'd never take that rifle to a shooting match.
I don't regret the experience and I learned a lot. What I remember most is that I'm not interested in doing that again.
I found it to be tedious and quite time consuming. I did manage to improve the accuracy considerably but needless to say I'd never take that rifle to a shooting match.
I don't regret the experience and I learned a lot. What I remember most is that I'm not interested in doing that again.
To elucidate just a little further, I'll describe what I do which may or may not be the best way to do things. I have a turned down jag for a Parker-Hale rod. The jag is about 1/8 inch in diameter and 3/4 inch long. There are grooves cut around this core. I wrap some string around the base of this jag and set it about 1 1/2 inches back from the muzzle. Then I warm the barrel up until it will just sizzle water. Then I pour lead down the barrel and let it solidify. Push the lap out a half inch and dress the front so it will pull back into the barrel easily. Now I push it all the way out and remove the thread. Next I smear lapping compound on the lap and get some down the barrel behind the lap. If this is a new blank which is not lapped, and I am just trying to achieve a better finish, I'll probably use a 400 grit clover compound and just start stroking. I set a block at the front of the barrel so I don't push out of the barrel. If I feel a tight spot, I'll concentrate on that spot. If the dimensions seem uniform, I'll just give it about fifty strokes, inspect, and either quit or continue. If the lap gets loose, I'll bump the lap against a rod inserted into the barrel and bump up the diameter.
If this is a chambered barrel, I'll start at the throat and work my way forward. The throat is the critical area because the reamer often leaves a bit f a feathered edge on the following side.
If the barrel is one with a lot of dimensional variation, I'll use a 240 grit Clover compound and work on the high spots until I get the barrel as uniform as I can. This requires a lot of recharging of the lap with a more aggressive compound and may require the use of more than one lap. Changing dimension with a lap takes considerable time and effort. This is kind of a simplified description and I've left a lot out. This isn't because I don't want to say, just because I'm having trouble getting into a real typing mood! WH
If this is a chambered barrel, I'll start at the throat and work my way forward. The throat is the critical area because the reamer often leaves a bit f a feathered edge on the following side.
If the barrel is one with a lot of dimensional variation, I'll use a 240 grit Clover compound and work on the high spots until I get the barrel as uniform as I can. This requires a lot of recharging of the lap with a more aggressive compound and may require the use of more than one lap. Changing dimension with a lap takes considerable time and effort. This is kind of a simplified description and I've left a lot out. This isn't because I don't want to say, just because I'm having trouble getting into a real typing mood! WH
DocBII
Gold $$ Contributor
rebs,
1. No, only to do it right.
2. NECO used to sell a lapping kit for bullets. Lead bullets with compound are aggressive, copper bullets not as bad. They listed customs loads with fast powders. I'd use range pickup cases and toss them if you go the bullet route. You can also use the lapping compound on patches for addressing a tight spot or a new throat. Only do this on non-custom barrels.
Will Henry describes how to create lead laps for your barrel. Lots of information out there on this, search and read a lot before trying it. It wouldn't hurt to find someone with some experience to mentor you if you decide to try this.
HTH,
DocBII
Really? Do tell. LolIt's also not very difficult to paint a car.
DShortt
Gold $$ Contributor
I can paint a car. Now if you don't want brush strokes, best find someone else.
DShortt
Gold $$ Contributor
The problem with using bullets and abrasives is you can't concentrate on uneven areas, nor avoid oversized areas. Poured laps, lots of time, several laps and experience are all needed if you expect fine accuracy afterwards. There's also the final finish to consider. The wrong final finish will create new problems.
I lack the experience and just am not interested in the learning curve to aquire it. Which is why I don't plan to do any more.
I lack the experience and just am not interested in the learning curve to aquire it. Which is why I don't plan to do any more.
scasa
Silver $$ Contributor
I have done a couple . I made a lapping rod with a ball bearing handle and I use my lathe to hold the barrel. To me the hardest part is pouring a decent lap but once you get that the real work begins. Its a real workout to lap a barrel but I've had good results. I've only done rimfire barrels.
LVLAaron
Gold $$ Contributor
Alex Wheeler
Site $$ Sponsor
Can I ask for some more detail? Like many things, its easy to do but to do right takes experience. If you have a more specific question or problem maybe we can help more.
rebs
Gold $$ Contributor
I wanted to remove some fire cracking
You can smooth out the cracking by fire lapping, but you will be lengthening the throat. This is a case where you are actually just concerned with the surface finish, so polishing is the answer. Of course, the real answer is to set the barrel back enough to get a fresh throat! WH
Alex Wheeler
Site $$ Sponsor
Lapping will not fix that. If you did you would end up with an oversized barrel thats ruined. A little JB sparingly will help a little but theres no fixing it.
rebs
Gold $$ Contributor
Thank you for your help. I have about 1 to 1 1/2 inch of fire cracking. Is this enough to hinder accuracy ?
Bob
LVLAaron
Gold $$ Contributor
Only if you do a bunch of work to it and ruin it.
I've seen barrels with a foot of what looks like smuggled alligator still shoot a clean target, or damn close. Let the target tell you.
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