bronko22000

Guys - I read an interesting article in an old book I have about lapping your ML barrel or more specific, how to make a lapping plug and thought I would pass it along.
To make a plug, put two or threedamp patches about 4" down the muzzle and insert a clean brass brush into the bore leaving the threaded end exposedthenpour molten lead carefully around the brush. Be sure the lead is hot enough to flow down to the opposite end of the brush and to be around the entire circumference. Once the lead solidifies, screw the ramrod onto the brush and pull it out. Trim any excess off the end and remove the patches.
To lap the bore, appply polishing compound like JB to the plug and work it back and forthe through the barrel.
I tried it with an old T/C .45 barrel I have and it works pretty good. And if you're concerned about the excesslead, it does not stick to the steel barrel and just falls out or comes out when you remove the patches.

cayugad

I lapp them with valve grinding compound and patches. It removes a little at a time and really does a nice job. Also then I do not have to fool around with molton lead. I have a friend that does it the way you described and you're right, it does a great job.

You can fire lapp them as well, but be careful. Just apply valve grinding compound to REAL Conicals and shoot them off with moderate charges. After ten shots, clean the barrel and check the amount of barrel that has been removed. I have never done this, but heard of others doing it...

falcon

i have lapped high power rifle barrels using the method Bronko describes. It works well.

The bore of my new Encore was very rough. It washard to clean properly and loaded very hard. Used red jeweler's rouge on a patch and jag. After about 15 minutes and five patches coated with jewelers rougethe barrel was much smoother.The barrel is much easier to load and clean.The gun also seemsto be more accurate.

Semisane

I've fire-lapped several guns, both black powder and cartridge,with fire lapping bullets from Beartooth Bullets.

The worst results were "pretty good", the best were"outstanding".

Had a .357 Mag Ruger stainless Blackhawkrevolver go from 6 or 8 inch 25-yard groups to 11/2 inch25-yard groups. The gun had a bad constriction where the barrel screwed into the frame and the bullets were being swaged down by it. Fire lapping eliminated the constriction but it took about two dozen lapping bullets with the stainless barrel. Hada blue Ruger Blackhawk .41 Mag go from 12" to 6" 100 yards groups with a scope from a bench rest. It took only a dozen fire lapping bullets.

Fire lapped my Lyman Mustang and shaved just an inch off 100 yard groups with the same bullets and loads, BUT gained a whole lot in ease of loading and cleaning. It really reduced fouling levels.

If you haven't already seen Beartooth's technical notes on fire lapping muzzleloaders, you need to give it a read. Link is below.

http://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/48

DavidVanVorous

FWIW,
There was a write up on both the materials, procedure and results a while back in Muzzleloader magazine (ca 1992-4). IIRC they put 10 shots with 3 grits through and managed to salvage what was basically a shot out-rusted out bore after they were done. Believe that they used something a bit finer than just valve compound...

Myself, Im real reluctant to go through either lapping exersize unless the bores get REAL bad as seen with a bore scope. As yet neither my TC (vintage 1976) or my home built (36" Green Mt 1:70 twist) are that bad... even after having sent roughly 3000 rounds of Goex 2f through the pair of them...

Keep yer powder dry,

D.

Semisane

I use the bore lapping compound made by Lead Bullet Technologies (LBT).

It's a very, very fine abrasive in a viscous oil.

http://www.lbtmoulds.com/measurebore.shtml

dmurphy317

The one gun I felt a need to lap the barrel turned out good. It is a CVA Bobcat that had a slightly undersized bore at .498 to .499. I used a combination of fire and hand lapping. I bought the fire lapping kit from MidwayUSA which comes with 3 different grits and two plates to use to embed the compounds into the bullets. If you consider using this method, proceed with caution. It can remove metal quicker than you may realize. I used about 10 of the coarse grit to open the bore up a bit then used 5 each ofthe finer grits to start polishing it. After the fire lapping it had brought the bore up to .500 with only around 20 shots. I then hand polished the bore using 1200 grit polishing compound on a tight fitting patch and bore brush then a jag. I did around 200 strokes with this combo and ended up with a very smooth and shiny bore that loads and shoots well. Final bore size is just a shade over .500.

Again, use caution when fire lapping especially with the coarser grits. You cannot replace the metal once it is gone. Clean and remeasure the bore after every few shots to confirm where you are before moving forward.