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Hand lapping a barrel
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paulvallandigham
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Remove the Breechplug from the barrel. Make a lap. You need a long steel rod, and it can stand to be threaded to have two washers held in place, so that the lead lap can be poured between the two washers. You use washers, or tape, or muzzle protectors to help center the rod in the barrel, and then pour the pure lead lap. You trim off the excess so that it moves in the barrel. Then you put your lapping compound on the lead lap, tighten the washer on the end up against the lead lap, and begin making strokes in the barrel. You can make your lap whatever length you desire, but a 4 inch long lap is sufficient.
There are several ways to lap a barrel, depending on what you want in the barrel. If you are simply smoothing out the rifling, or removing microscopic burrs on the lands, then move the lap in and out the entire length. When the lap seems to be getting too easy to pull through the barrel, push part of the lap out of the breech end of the barrel and tighten the screw-held washers 1/2 turn, and see how much tighter the lap gets in the barrel. Add more lapping abrasive, and pull it through the entire barrel, but don't ever pull it out of the barrel.
If the lap comes out at either end of the stroke, you will be pouring a new lead lap, as its next to impossible to get something that fits this close back into the barrel and rifling.
If you want to put CHOKE in the barrel, for decide what kind of choke you want: At the muzzle only, or do you want the choke to taper over the entire length?
{HINT}This gets to be real work, without machine equipment, so take some time to decide this one!
If you want to choke the muzzle, then begin by running your lap the whole length of the bore for 50 strokes, back and forth. Now, move down from the muzzle eight inches, or so, and put some kind of stop on your rod- a piece of tape works. Now, lap the back end of the barrel to that mark another 50 times in and out, tightening the lap to make sure you are removing a bit more metal from that rear section of the barrel.
You are only removing a few 10,000ths of an inch of metal with all this work, so don't expect to be putting a "ridge" in the barrel. When you finish, you can use that last lap to stroke the entire length of the barrel to get rid of any " steps" you might feel. The lap will be squeezed by each area that is tighter than the last, but eventually, you will feel a smooth, gradual tightening from chamber to muzzle.
There are barrel makers who do step choking, where they do the barrel in quarters or eights of the length, doing 50 strokes each time they shorten the lapping from the muzzle. This makes the bore and grooves WIDER back where the powder and ball sit, so that the ball at first expands back there when the gun is fired. Then, as the ball progressed down the barrel, the bore becomes more narrow, or tighter, Or "choked", on the PRB, or conical.
You can expect to have to pour a couple of laps over the time you are lapping the barrel, as there is only so much tightening of the lead lap that can be done with that washer and screw.
Lapping was originally done to try to provide a better Seal against the powder gases cutting around the PRB. Later, target shooters did lapping to help them shoot better scores. They still do.
I have heard of target shooter lapping their barrel every night between matches, trying to get a bit better barrel by reducing the height of the lands and getting a new "EDGE" on the lands. These guys are also said to go through a barrel every year, and pay thousands of dollars for a new barrel each year to begin the target shooting season all over again.
Personally, I am not interested. What they are doing sounds too much like a lot of hard work, and that is no fun to me.
I have loaded and fired a lapped barrel with choke at the muzzle. You can FEEL the difference when loading the PRB, and just cleaning the barrel. The gun shot very accurately, and was very easy to clean.
NO one keeps shooting winning scores the rest of their life. We all have days when you just don't do it, for any number of reasons. Even Tiger Wood comes in second in some golf matches.
If you set out to make shooting a way to BEAT all the other shooters, you are headed for a great disappointment. No one becomes a winner, with just equipment. Its the shooter behind the gun, not the gun that makes the winning possible, and you lose a lot of shooting matches learning the skills, before you reach the level of being a championship level shooter.
Some people never get there, no matter how much they practice or how expensive a gun they shoot. Its that way with all sports, and all skills.
I once beat the Indiana State Trapshooting Champion at a small club Registered shoot using my old Remington Wingmaster model 870 pump shotgun. I just shot a better score that day. But, he was shooting a $5,000 gun and apparently was particularly angry that he was beaten by a total strange shooting such an "inferior gun".
He stormed out of the club when he found out he came in second, not even taking the time to find me and introduce himself, or congratulate me.
I would not know him from Adam, then or now, but it would have been an honor to meet someone who was that capable a shooter. And, it would have been nice to been congratulated by him for my win.
The first thing I would have said to him was, " Well, Don't hold your breath expecting me to out-shoot you again anytime soon! I shot 10 targets over my average, and you were probably 2 targets off yours!!!" Then I hope we would have both had a good laugh about it.
There are other ways to make a lap, but this is an " easy " way to do with only hand tools. Be careful of the molten lead, when you pour the laps.
As for lapping compounds, they are sold in auto supply stores as " valve grinding compounds". You can find rottenstone at most paint stores, and sometimes, powdered pumice, too. I know one man who uses Pearl Drops Toothpaste, and another how uses Crest toothpaste for his lapping compound. Check the sites for gunsmithing supplies, like Brownells to see what they are selling, too. See their "link" at the top of the index page, here.
There are several ways to lap a barrel, depending on what you want in the barrel. If you are simply smoothing out the rifling, or removing microscopic burrs on the lands, then move the lap in and out the entire length. When the lap seems to be getting too easy to pull through the barrel, push part of the lap out of the breech end of the barrel and tighten the screw-held washers 1/2 turn, and see how much tighter the lap gets in the barrel. Add more lapping abrasive, and pull it through the entire barrel, but don't ever pull it out of the barrel.
If the lap comes out at either end of the stroke, you will be pouring a new lead lap, as its next to impossible to get something that fits this close back into the barrel and rifling.
If you want to put CHOKE in the barrel, for decide what kind of choke you want: At the muzzle only, or do you want the choke to taper over the entire length?
{HINT}This gets to be real work, without machine equipment, so take some time to decide this one!
If you want to choke the muzzle, then begin by running your lap the whole length of the bore for 50 strokes, back and forth. Now, move down from the muzzle eight inches, or so, and put some kind of stop on your rod- a piece of tape works. Now, lap the back end of the barrel to that mark another 50 times in and out, tightening the lap to make sure you are removing a bit more metal from that rear section of the barrel.
You are only removing a few 10,000ths of an inch of metal with all this work, so don't expect to be putting a "ridge" in the barrel. When you finish, you can use that last lap to stroke the entire length of the barrel to get rid of any " steps" you might feel. The lap will be squeezed by each area that is tighter than the last, but eventually, you will feel a smooth, gradual tightening from chamber to muzzle.
There are barrel makers who do step choking, where they do the barrel in quarters or eights of the length, doing 50 strokes each time they shorten the lapping from the muzzle. This makes the bore and grooves WIDER back where the powder and ball sit, so that the ball at first expands back there when the gun is fired. Then, as the ball progressed down the barrel, the bore becomes more narrow, or tighter, Or "choked", on the PRB, or conical.
You can expect to have to pour a couple of laps over the time you are lapping the barrel, as there is only so much tightening of the lead lap that can be done with that washer and screw.
Lapping was originally done to try to provide a better Seal against the powder gases cutting around the PRB. Later, target shooters did lapping to help them shoot better scores. They still do.
I have heard of target shooter lapping their barrel every night between matches, trying to get a bit better barrel by reducing the height of the lands and getting a new "EDGE" on the lands. These guys are also said to go through a barrel every year, and pay thousands of dollars for a new barrel each year to begin the target shooting season all over again.
Personally, I am not interested. What they are doing sounds too much like a lot of hard work, and that is no fun to me.
I have loaded and fired a lapped barrel with choke at the muzzle. You can FEEL the difference when loading the PRB, and just cleaning the barrel. The gun shot very accurately, and was very easy to clean.
NO one keeps shooting winning scores the rest of their life. We all have days when you just don't do it, for any number of reasons. Even Tiger Wood comes in second in some golf matches.
If you set out to make shooting a way to BEAT all the other shooters, you are headed for a great disappointment. No one becomes a winner, with just equipment. Its the shooter behind the gun, not the gun that makes the winning possible, and you lose a lot of shooting matches learning the skills, before you reach the level of being a championship level shooter.
Some people never get there, no matter how much they practice or how expensive a gun they shoot. Its that way with all sports, and all skills.
I once beat the Indiana State Trapshooting Champion at a small club Registered shoot using my old Remington Wingmaster model 870 pump shotgun. I just shot a better score that day. But, he was shooting a $5,000 gun and apparently was particularly angry that he was beaten by a total strange shooting such an "inferior gun".
He stormed out of the club when he found out he came in second, not even taking the time to find me and introduce himself, or congratulate me.
I would not know him from Adam, then or now, but it would have been an honor to meet someone who was that capable a shooter. And, it would have been nice to been congratulated by him for my win.
The first thing I would have said to him was, " Well, Don't hold your breath expecting me to out-shoot you again anytime soon! I shot 10 targets over my average, and you were probably 2 targets off yours!!!" Then I hope we would have both had a good laugh about it.
There are other ways to make a lap, but this is an " easy " way to do with only hand tools. Be careful of the molten lead, when you pour the laps.
As for lapping compounds, they are sold in auto supply stores as " valve grinding compounds". You can find rottenstone at most paint stores, and sometimes, powdered pumice, too. I know one man who uses Pearl Drops Toothpaste, and another how uses Crest toothpaste for his lapping compound. Check the sites for gunsmithing supplies, like Brownells to see what they are selling, too. See their "link" at the top of the index page, here.
The question that comes to mind is what are you trying to achieve with lapping.
Break in a new barrel? Clean up an old barrel? Or what?
It's pretty easy to ruin a perfectly good barrel, by lapping, if you don't know what you are doing. Moreover, your barrel may not really need lapping.
There may be another, easier solution to whatever problem you are facing with that barrel.
So the question arises, What are you trying to achieve?
Break in a new barrel? Clean up an old barrel? Or what?
It's pretty easy to ruin a perfectly good barrel, by lapping, if you don't know what you are doing. Moreover, your barrel may not really need lapping.
There may be another, easier solution to whatever problem you are facing with that barrel.
So the question arises, What are you trying to achieve?
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The lapping of barrels by an amatuer should be restricted to barrels with such problems that cannot be resolved otherwise, or one that is in such poor condition, that no harm can be done, only. It is quite an undertaking, and very time intensive. I have done three. All were improved, but all were in serious condition before I started. A good barrel can be made into a great barrel with proper lapping, but that requires much experience and know how.
As the others have said, we need to know what kind of "lapping" your after.
If it is just to break the sharp edges off of the rifling grooves anyone with a good cleaning rod, a brass cleaning jag, some 0000 steel wool, some oil and a lot of elbow grease can do a good job without damaging the barrel.
Lapping to remove deep corrosion, uneven bore size or to improve worn rifling is a totally different matter.
If it is just to break the sharp edges off of the rifling grooves anyone with a good cleaning rod, a brass cleaning jag, some 0000 steel wool, some oil and a lot of elbow grease can do a good job without damaging the barrel.
Lapping to remove deep corrosion, uneven bore size or to improve worn rifling is a totally different matter.
Green scotchbrite and cutting oil on a small jag will remove the rust and help it load smoothly. If you don't have cutting oil just use WD40 etc.
paulvallandigham
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YOu asked about lapping, so I just thought you were wanting to know how its done. Now that you indicate WHY you thought you should lap your barrel, Go with R.C., and Rich Pierce's advice.
Rust, unless its disasterously deep, can be more easily removed by either just shooting the gun- the coarse patch material will burnish off the rust-- or by using the Scothguard green cleaning pads, with some oil on it to polish off the rust.With what I know about lapping, there is NO WAY I would take the time to make a lap to simply remove rust from a barrel. If the rust is so deep as to leave serious pits in the bore, better to simply replace the barrel, than to try to lap out the pits. Doing so will change the bore diameter, and require a larger diameter projectile, etc.
My brother had a barrelsmith unbreech an original barrel for him, some 25 years or more ago, and see what it would take to remove the pits in it. The pits were so deep that the bore had to be drilled out, and then reamed even more, enlarging the bore from about .34 caliber, to .42 caliber. He got out all the deep pits, and the barrel shoots just fine, but lapping would never have done that job if Pete was still doing it! :shocked2:
Rust, unless its disasterously deep, can be more easily removed by either just shooting the gun- the coarse patch material will burnish off the rust-- or by using the Scothguard green cleaning pads, with some oil on it to polish off the rust.With what I know about lapping, there is NO WAY I would take the time to make a lap to simply remove rust from a barrel. If the rust is so deep as to leave serious pits in the bore, better to simply replace the barrel, than to try to lap out the pits. Doing so will change the bore diameter, and require a larger diameter projectile, etc.
My brother had a barrelsmith unbreech an original barrel for him, some 25 years or more ago, and see what it would take to remove the pits in it. The pits were so deep that the bore had to be drilled out, and then reamed even more, enlarging the bore from about .34 caliber, to .42 caliber. He got out all the deep pits, and the barrel shoots just fine, but lapping would never have done that job if Pete was still doing it! :shocked2:
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