That sounds about right.  Better would be the lightest load with these powders that gives you a reasonably consistent group at 50 yards.  If you are using Clover compound, the abrasive is mixed into some kind of grease, which will give at least some rudimentary lubricating qualities to the bullet.  I've never noticed any evidence of pressure spikes when fire lapping, but I normally use a light load of Unique, just enough to get the bullet to the short range target consistently.  I do get some leading, but this is to be expected.

Use one case, decapping and loading at the range.  Seat bullets by hand, carefully placing the cartridge in the chamber so the bullet doesn't move back.  Wipe off the case and chamber after each firing, decap and reload.

I clean the bore with a brush every five lapping shots, and patch until all the lead splinters and black stuff comes out.  I fire all shots at a target at 50 yards, just to keep track of what is going on.

After every 20 or 30 shots (5 or 6 cleanouts), I fire a group of five lubricated bullets of the same type, out of the same lapping case, just to see if any change in group size is occurring.

As the groups continue to shrink (hopefully) I continue the 5 shots, brush, wipe, check, routine.  Remember that the worst roughness will be the area that picks up the heaviest lead, which will protect the surface you want most to smooth out.  You don't want to abrade the good parts of the barrel unnecessarily , especially the throat, if it is in good shape.

I generally notice the barrel gets noticeably warmer when I fire lapping rounds.  This is logical, as the abrasive will be causing friction.  It shows the lapping is working.

Eventually, from the groups made with the regular bullets, I figure that I've reached an optimum and that further shooting won't help.  It might take two or three range sessions to come to this conclusion.  Since each shot is one "stroke" in hand lapping, it may take a hundred or more shots, depending on how bad the barrel is.

The lapping case is either stored with other lapping cases or destroyed.  Returning it to service will scratch loading dies and generally make a mess of things.

I've never injured a barrel with a fire lapping job, and have markedly improved several.  Of course, I don't fire lap perfectly good barrels, or use jacketed bullets, or blast a hundred lapping rounds one after another, or perform any of the other innovations that those who say fire lapping is no good seem to do.

I recommend installing a liner. Then hand lap a taper in it. If somethings worth doing, it's worth doing right. 

         Joe.

frnkeore wrote on Oct 18^th, 2015 at 3:29pm:


Frank before you decide to go for a reline, try a few paper patch bullets through it. Back in the old days most of Sharps LR Target Rifles had PP barrels with only 2-3 thou' depth of rifling. You never know, and it's not as expensive as a barrel liner.
Harry

It was 4 to 4.5 gr Unique behind the Ideal 257283.  If I recall, I used the culls from a casting session, without gas checks for the lapping rounds and the good bullets, sized, lubed and checked for the test rounds.  I rolled the bullets between two pieces of ground flat stock.  My default abrasive is Clover 320.

The breech seating is worth a try, but the lapping compound, in my experience, embeds in the brass shell on firing, to some extent.  I don't know if it would embed in a breech seater; might be better to use a wooden dowel of the proper size.

Not to put too fine a point on it, fire lapping (or hand lapping, for that matter) will not turn a pitted barrel into a National Match contender.  But, as I said, I've never done any harm to a barrel and some have improved pretty dramatically.  This includes some commercial reline jobs that didn't seem to be shooting all that well.

One that didn't work, alas, was a .25-20 barrel which was perfect except for the inch or so ahead of the chamber.  Corrosive primers had etched an irregular, pitted freebore in the leade, and accuracy was mediocre before and after the fire lapping.  That one I had relined.

But it's always worth a shot.  At the very least, you learn something.

A buddy once went overkill fire lapping a rough one. even though the loads wete light the lead bumped a bit and washed the throat out much before the bore was lapped smoothe.he now uses jacketed bullets for extreme lapping and reports not having the issue anymore.