W
woodburner
Guest
Will some one out there tell how to Hand Lap a barrell
M
MKane
Guest
Never done it myself. Push slugs down the bore to locate tight spots, use lapping compound and lap until pressure feels the same throughout the push. Don't lap out choke at the end of the push.
woodburner, I seriously doubt that anyone who is highly experienced at lead lapping a rimfire barrel, will explain to us exactly how the work is performed.
However, I have lapped a couple of cut rifled muzzleloading barrels in my younger days. Basically, I used the core of a brass bore (bristles removed) cleaning brush to cast the lead lapped around. The core was attached to a cleaning rod, centered in the bore, about three inches from the muzzle/crown. The bottom of the core area was sealed, so the hot moulting lead would not get beyond that point. Before pouring the lead into the muzzle, the barrel was heated with a propane torch so that when the lead entered the bore it would cast a lap without any voids. When the metal cooled down the lead lap was withdrawn out the breech end of the barrel. Lapping compound is applied to the lap and smoothly worked up and down the bore. A guide should be used on the rod so it does not contact the bore during the lapping process.
One of Bill Calfee's books has a photo of him taper lapping a rimfire barrel, but does not go into great detail of how it is actual done. He used a jig (fixture) mounted on a bench, with what appears to be a rod guide made of Delrin (plastic) and a T-handled steel rod for his lapping process. Apparently, if performed correctly the work is labor intensive. Best to try any testing on an old barrel. Hope these basics give you a glimps of how lead lapping is performed. John
M
MIKECAMERON
Guest
hand lapping a 22rf barrel is an art and should be left to the professionals, it is a complicated process which includes heating the barrel to cast the lap properly to the abrasives to use.If you have a chamber in it you have to make a precision guide for the lap also, it is complicated.
Not so much complicated as it is difficult. Further, the difficulty lies in the unknown in terms of how hot both the barrel and lead should be to get a good casting of the lap - and what grit of lapping compound to use. Sewing thread, wrapped tightly, can be used to seal the bore and the lap is poured much as center22 described. Once COOLED, the lap can be PARTIALLY extended from the bore, any "sprue" can be cut off, and lapping compound/oil applied. Don't push the lap completely out of the barrel. One might think that the final "grit" would be finer but I think a good stopping point is 320. The first few strokes may take some strength.
Think about what you're doing here. The soft lead will conform to the tightest spot on the first stroke and wear that tight spot down on subsequent strokes more quickly than the rest of the barrel. When the first lap runs smoothly, pour another and repeat perhaps with finer compound. In time (not much time), the tight spots will disappear and you're done. An unlapped barrel is better than an overlapped barrel.
Think about what you're doing here. The soft lead will conform to the tightest spot on the first stroke and wear that tight spot down on subsequent strokes more quickly than the rest of the barrel. When the first lap runs smoothly, pour another and repeat perhaps with finer compound. In time (not much time), the tight spots will disappear and you're done. An unlapped barrel is better than an overlapped barrel.
Boyd Allen
Active member
I have seen lapping done the way that Wilbur described, at a barrel maker's. I think that applying the compound that way might contribute to belling the muzzle. Of course that is not a problem for a barrel manufacturer, given that the gunsmith will cut that part off. Of course I could be all wet on this.
A friend has figured out a way to oil the bore, and apply the compound to the bore with a mop, after pulling the lap to the rear of the barrel. That way he can start at the back, and pretty much leave the muzzle alone. He has done this on a rimfire barrels, with good results, but be warned. He is as good, smart, and hard working as anyone could be, and one of the barrels took him 3 1/2 hours to do. Knowing him, he wasted none of that time.
A friend has figured out a way to oil the bore, and apply the compound to the bore with a mop, after pulling the lap to the rear of the barrel. That way he can start at the back, and pretty much leave the muzzle alone. He has done this on a rimfire barrels, with good results, but be warned. He is as good, smart, and hard working as anyone could be, and one of the barrels took him 3 1/2 hours to do. Knowing him, he wasted none of that time.
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X
xs hedspace
Guest
So, what grit does one use on the lap? I have lots of 220 grit. Took borescope photos every 10 rounds of a .22 barrel I firelapped with 50 rounds(!) rolled in 220 grit. Had a reamer smear in the throat, all the 220 grit did was to polish the smear and lands nicely. It was a Biakal combo 22/20 ga, BTW, and I rechambered it to .22 mag. Shoots as good as I can hold, with a ghost ring rear sight, now.