barrel work question

[filmmaster]

I have seen the following ideas for fixing a rough barrel, or a barrel with constriction at the threads..

1. valve compound on a tight fitting patch, one stroke through whole barrel followed by 3 in the thread area, repeat till happy

2. loading up wadcutters and using valve lapping compound in the lube grooves and firing. supposed to destroy the dies used.

3. soaking a patch/jag or bore mop in lapping compound, and swabbing the barrel between shots of wadcutter or mild to medium lead bullets

WHat will actually do the best results and not take 3 years to do?

 

[Protocall_Design]

The best way is to remove the barrel, turn back the shoulder on a lathe until it screws on to about 1 o'clock (looking from the rear of the gun like you would shoot it) by hand, then finish tightening. When you take the barrel off, it will spring back to original diameter. Then you can put it back on, not as tight. If the constriction is less than .003, it will spring back. Most of the ones I've seen are .002 or less.

Valve lapping compound is too coarse. You need 400 or finer grit lapping compound. You want to get Aluminum Oxide abrasive instead of Silicon Carbide abrasive. The SC will imbed in the steel, the AO will not.

Abrasive on a tight fitting patch will polish the bore, if overdone will wash out the rifling, but not fix the constriction. Low velocity wadcutters or other lead bullets with lapping compound will even out the bore diameter. Depending on some variables, usually 20 to 50 shots will do. You need to clean the barrel and measure the progress after every 10 shots. You don't want to run more shots than needed to get the desired results.

 

[dfariswheel]

Using an abrasive and a patch will not do the job, and may well ruin the barrel.

Options are barrel set-back, hand lapping, and fire lapping.

Barrel set-back may or may not remove all the constricted area and calls for the services of an real expert pistolsmith with the correct tooling and gauges.

Hand lapping is somewhat difficult.
To do this you put a rod down the barrel and cast a lead lap on the end.
Without fully removing it from the bore you apply fine lapping compound and work the lap back and forth.
To change grits or check the progress you have to cast another lap since you can't remove it and get it back in the bore properly.
The advantage is, you can lap only the required area.

Other then actually hand lapping the bore, probably the best option other then a barrel set-back is a "fire lapping" kit.

These are various grits of fine abrasive that you embed into bullets, hand load with light powder charges, and fire through the barrel.

No less an authority then David Tubb uses this system in Match rifle barrels.
His kits are more expensive..........

Wheeler Bore Lapping Kit

PRESSURE(FIRE)LAPPING NECO Shop Online | Neconos.com

I wouldn't use auto store lapping compound, it's usually too coarse.
I'm not sure, but I think the abrasive kits use a special non-embedding abrasive that is easier to get out.

A friend did this some years ago to an old .38 Special revolver with a rough barrel and he wanted to see if it helped.
Back then he bought a kit that came with the correct bullets already embedded with abrasives, and with hand loading data on powder charges.

Start out by giving the bore and chambers a THOROUGH cleaning to remove all leading and fouling. Start off clean.

Embed the abrasive in the bullets and load with LIGHT charges. How light I don't know but either the kit or the kit makers should have data available.

After shooting the first grit, THROW THE CASES AWAY.
The abrasive will embed into the cases and cross-contaminate the next grit.
Use fresh cases for each grit.
Some kit makers say the cases can be cleaned, but it's not worth the risk.

Thoroughly clean the bore and chambers after every grit, and do a thorough job after the process is finished to remove all the grit.

CLEAN YOUR LOADING DIES TOO.

 

[243winxb]

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