Lapping the 10ML-II barrel:
written by, Drifter
One
method used to improve the accuracy of a rifle is lapping the barrel. The
process removes burrs created by the process that cuts the rifling into the
barrel. The overall goal is to smooth the barrel somewhat, while of course
keeping the rifling intact. Burrs and other rough spots on a barrel are particularly
hard on plastic sabots, making it important to do this to guns shooting plastic
sabotted bullets.
From the breech end (breech plug removed), use a .50 caliber jag and a patch
(called a lap) coated with J&B Bore Cleaning Compound.
Using
the rod, push the patch up and down the barrel about 50 round trips. Replace
the patch with another one coated with J&B occasionally, always adding it
when the lap is at the breech end in order to remove more metal from this
end as compared to the muzzle end. Make sure the jag and patch fit tight enough
by making sure the ramrod revolves with the rifling (one revolution per 24")
as it goes up or down the barrel.
After 50 round trips, thoroughly clean the barrel with solvent on a patch,
repeating as necessary. Follow this with a few strokes with a brass bore brush
with the same solvent on it, finishing with dry patches until they come clean.
You may use a canned brake cleaner to spray out the J&B before using the solvent.
You should consider removing the barrel from the stock to do this to avoid
getting the cleaner on the stock.
Repeat in groups of 50, at least 5 times to total 250 round trips with the
lap and bore cleaning compound. After the last time, clean and lightly oil
the barrel as per any firearm. Use an anti-seize compound on the breech plug
and replace it as usual. Brake cleaner and anti-seize are available at John
Deere tractor parts counters, among other places.