badly rusted bores?

[K31]

In my experience, a bore that looks pitted, but feels reasonably smooth when you run a patch through it, will shoot cast bullets alright. If it rips little pieces of patch out, forget cast bullets. A bore that rough also rips up jacketed bullets, and might be improved by lapping.

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[Merle]

In my experience, a bore that looks pitted, but feels reasonably smooth when you run a patch through it, will shoot cast bullets alright. If it rips little pieces of patch out, forget cast bullets. A bore that rough also rips up jacketed bullets, and might be improved by lapping.

I never thought about the patch test - thanks. Shame on me!
I would have to be very careful about lapping - there isn't much rifling left as is.
The Carcano is the worst for shallow rifling.

[gandog56]

I would think about trying some firelapping.

[buffdog]

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First of all...really clean the bores. Cast bullets do not shoot well if any copper fouling is present. Do not shoot cast bullets, then jacketed bullets or vise-versa without a thorough cleaning between firing the two types. Copper fouled bores will really open up groups.

Fire lapping was mentioned in another post. Basically, fire lapping is taking a cast bullet, coating it with an abrasive material, and shooting a few through the rifle. You then clean the bore, load a few more cast bullets using a finer abrasive material, and fire them. Clean again, repeat the firing with even finer grade abrasive material, and clean again.

You can also lap a barrel using a cleaning rod and pouring a lead lap onto the end of the rod. I have used this method successfully in improving a bore. You have to put a patch on the rod about 6 inches from the tip, put it into the bore from the breech end, leaving the tip about one inch inside the muzzle. You then pour melted lead into the bore from the muzzle end, leaving about a 4 to 6 inch lead slug on the rod. Tap the rod so that the slug moves about 1/2 inch out of the muzzle, leaving the large portion of the slug in the bore. Trim off the excess lead, then move the rod out to expose about 2 inches or so of lead. Coat the lead with the abrasive, then carefully swab the bore back and forth about 15-20 strokes. Make sure the lead lap DOES NOT COME OUT OF THE BORE. If it does, do not try to put it back by aligning the grooves...cast another lap. Repeat as in fire lapping with progressively finer abrasive materials.

You will probably feel a few places in the bore where it is harder to push the lap. Give them a few shorter strokes in that area. These are tight spots in the bore. After a bit, you will get an even pressure on the rod all the way through the bore.

There are kits available that will give you the proper size of abrasive material. DO NOT, ABSOLUTELY, DO NOT USE AUTO VALVE GRINDING COMPOUND. THIS STUFF IS WAY TOO COARSE, EVEN IN THE FINER GRADES, AND WILL REALLY RUIN YOUR BORE.

Light pitting is not really a problem. Many of these old military rifles really can shoot well with cast bullets. The big thing is to make sure the bores are really clean and do not mix up jacketed and cast bullets at the same firing.
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