lapping compounds

What do you use for lapping compounds? A friend says you can't beat Ultra Bright toothpaste for this kind of work.

that would do for very fine polishing Paul but 'lapping' as in finely fitted parts or honing marks 'Simichrome' is about the finest grade/grit that is useful. if you are 'lapping' a bore of a rifle as in 'hand lapped bore' you might try 3-M hand pads, grades go to 'ultra-fine' from about 220 grit. available at Ace hardware. cut a piece to use as a 'patch' on next size down jag.

Blizzard of '93 said:

that would do for very fine polishing Paul but 'lapping' as in finely fitted parts or honing marks 'Simichrome' is about the finest grade/grit that is useful. if you are 'lapping' a bore of a rifle as in 'hand lapped bore' you might try 3-M hand pads, grades go to 'ultra-fine' from about 220 grit. available at Ace hardware. cut a piece to use as a 'patch' on next size down jag.

Click to expand...

Blizz, may I ask if you have tried or heard about using JB bore paste in barrels to smooth away whatever small irregularities were left in manufacture?

Have tried it on new c&b revolver barrels & it helped. Not tried it in ml rifles yet, but am also gathering other's experiences with stuff like Simichrome, Flitz, & etc.

Have a new GM .32 barrel before me, and would appreciate any opinions as-to smoothing out a factory barrel as a matter of course. I am a little leery of using something too agressive.

hope I'm not hijacking your thread, Paul,

Thanks

I have heard of JB but never used it. I use the 3M hand pads in my work and found how useful they are. Simichrome is a very fine polishing paste, not agressive at all which will produce a near mirror finish but not remove any scratches or tool marks, for that you need a coarser polishing/lapping compound. Toothpaste is even finer than Simichrome or Flitz - used for polishing jewelry, mainly removing films and residue left from wearing. a 3M pad will go a long way, you can make many 'patches' out of one and as stated they come in progressively finer grits from around 220 (maybe coarser but that is coarsest I've ever had to use) down to ultra-fine. that will lap that barrel, use next size down jag as a lap or wrap around a bore brush.

I'VE USED JB FOR ABOUT 25 YEARS ON EVEYTHING FROM 50 CAL HANDGUNS, 100 YD RIFLES TO FLINTERS. IT WORKS VERY WELL FOR A FINAL AND INTERMITENT CLEANER/POLISH. COMPARING SIDE BY SIDE A RIFLE CLEANED WITH IT AND W/O IT DISPLAY A WORLD OF DIFFERENCE IN ACCURACY AND EASE OF CLEANING.

I USED TO GET SOME WORK DONE BY A RETIRED GUNSMITH OF THE MICHIGAN STATE POLICE (HE ALSO TOOK ME TO MY FIRST ML SHOOT AND EVEN PAID MY ENTRY FEE FOR A BALNKET SHOOT) HE TOLD ME TO LAP NEW BARRELS WITH 0000 STEEL WOOL AND LIGHT WT OIL. THE PURPOSE WAS TO KNOCK OFF THE EDGES FROM MACHINING. HE SAID AVE WAS 100 TIMES, TRY 25, SHOOT, 25 MORE, SHOOT...

A LOCAL BUILDER SLUGS THE BARREL WITH A LEAD SLUG PUSHED THROUGH THE BARREL 1000 TIMES WITH THE FINEST LAPPING COMPOUND HE CAN FIND (I THINK IT WAS 2000? GRIT) HE SAID YOU WILL GREATLY INCREASE THE SMOOTHNESS OF THE BARREL. HE SAID HE DOES TO ALL BARRELS (EVEN RICE AND GETZ). I WOULD BE INCLINED TO FOLLOW HIS ADVICE SINCE HE DID HIS 'PRENTICE IN COLONIAL WMSBURG AND WORKED SOME WITH PETE ALEXANDER, TOO.

I was taught with a lead slug and a brass rod made so the slug could spin freely down the barrel. And I used valve lapping compound, but I am sure that there may be better ways to do it. It always worked for me. :winking:

Thanks, fellas; just gave the new .32 bbl 100 strokes with JB (like I do on the C&Bs) - will see how loading/accuracy/cleaning goes in the next few days.

Was surprised at the relatively rough outside finish of this new GM barrel, and at the fine rust pulled out of the bore by the JB. Nothing huge, but surprising anyhow

Using a Scotch Bright patch will shine the bore, but if you want to even out any irregularities in the bore you will need to lap it using a lead lap. Pour a lead slug about 5 inches long around a rod, with good bearing, so it will rotate freely. Carge the lap with Clover lapping compound starting with 180 or 220. You will be able to feel any tight spots, work it till the bore is even, and you can even lap in a choke. Once the tool marks are gone and the bore is uniform finish with 320, 400 grit compound. When the lap gets "loose" clean the barrel and pour a new lap. It takes a while to do this right, and some expierance. It is very easy to go too far and have a loose spot or worse yet to open up the muzzle end. You can check the progress by driving an over size ball into the bore and pushing it through, or even a very tight patch, tight or loose places will be obvious. Go solw and think each step through. Clover compound is available from machine tool supply houses. Good Luck John

I don't know if this is anything that you'd find useful, but I surely have. Here's a link for firelapping muzzleloaders, I apologize if you've already been there, I know I post this link every time I see someone ask about lapping and someone's sure to omplain about me doing it sooner or later...
[url] http://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/48[/url]

HTH

shantheman said:

I was taught with a lead slug and a brass rod made so the slug could spin freely down the barrel. And I used valve lapping compound, but I am sure that there may be better ways to do it. It always worked for me. :winking:

Click to expand...

I'm no expert when it comes to lapping bores, but I have learned a bit from listening to people who are. I have lapped a coupla barrels with good success, so from my limited experience I can say that John Vaccaro is right on.

Valve grinding compound is not consistent in grit and can leave scratches in the bore. A consistent grit is necessary to remove any roughness and especially score marks made when the rifling cutter is run through the bore.

Steel wool or scotch brite pads are good for removing rust and sharp edges from the lands, but this is usually necessary only if those sharp edges cut the patching. They will not get down into the edges of the grooves where the bulk of fouling collects, so the only real effect is on the lands.

Semichrome and JB are for final poilshing, but I don't know if it is necessary to polish a bore that well.

Toothpaste contains a very fine abrasive and would probably work well to finish a bore, but IMHO, it's too fine to remove any imperfections.

I seem to remember using toothpaste for some aaspect of cleaning NM M-14 rifles, but CRS is kicking in, so I don't remember what is was.

We did use newspaper to remove carbon deposits from the gas piston and cylinder. Newspaper is also a very fine abrasive that will remove carbon deposits without damaging the polish on those mating parts.

J.D.

John has got it pretty much spelled out...Get a copy of the book from the muzzle loading ass titled "Shooting and Winning with the Champions"...Good section in there on lapping, rods, lead lapps and brass lapps and how to rum them...

To really get with it and uniform the bore (top of the lands) to real uniformity, need to finish up with a brass lapp that can be expanded to bore size...With the brass lap you can also put a little choke in there if you want too...

In any case barrels are lapped from the breech end not the muzzle...The work with steel wool and Scotch pads is just a polishing operation and takes the sharp edges off the lands...If your still cutting patches after working the 0000 wool, start looking at the crown, patching, and lub...Don't beleive you can make a uniform bore with them as they don't take material off the tight spots only....

IMO a nicely lapped barrel will shoot the first shot and the 2,000th or more shot the same as long as the muzzle crown doesn't get messed up.... :winking: ....The Lizard..

Here is a link to an old thread with my lapping setup.....it works very well!
Link to Old Lapping Thread