Rick ,if the barrel maker pushed his lapping plug through and it wasnt attatched to the rod isnt that about how it would come out...As was stated by the above poster, makers dont do fire lapping shearly because it isnt practical for their stage of the operation. They do however end up with an hour glass bore of a tenth or two. I end up with the same tenth or to but its consistantly large to small as from chamber out
I honestly haven't asked Dan Lilja or any others if they don't firelap because it isn't practical, because hand lapping is simply how they've always done it, or whatever. Has anybody here done that? I'd like to ask them, if all else was equal, whether they'd firelap their barrels.
HOWEVER... for starters, I'm not going to be lapping a Lilja, Krieger, etc barrel in the first place, by hand or by firelapping. My personal opinion is that the folks who make those barrels know a lot more about how to properly finish their barrels than I do. For me, lapping barrels is about dealing with factory Remchester type stuff, and therein lies the difference. If this is all about how to lap a Lilja or Krieger barrel after the makers have completed finishing their barrel to the best of their ability, then I am outta here, because I don't think I can improve on their skills and I wouldn't even try.
Lilja and others guarantee their barrels to a .0001". I know from handlapping many factory barrels that they don't even come close to that - I've simply felt too many tight and loose spots while running a lap. Custom barrel makers aren't trying to finish a factory barrel that has tight and loose spots in it, or refinish a pitted barrel in an older rifle, for example. They're putting the finishing touches on a barrel that is very nearly (if not already) .0001" uniform from end to end. When you're working on a factory barrel with one hell of a lot more variation in it from end to end, you're not finishing a barrel that has very tight tolerances - you're lapping all the tight spots out of it to start with. THEN you can finish it.
That's the difference between when a custom barrel is being finished and a factory barrel is being lapped. I lapped a Longbranch #4 Mk I in Bill Leeper's shop a couple of years ago. With the two of us taking turns going at it, it probably took a little over two hours of lapping to get that barrel uniform from one end to another, eliminating a couple of jugs that existed partway down the bore. I can't begin to imagine how many rounds you would have had to fire to eliminate the jugging and get the bore perfectly uniform - unless you decided to proceed with 50 grit Clover Compound or something like that.
As far as that goes, I don't know how you'd have a clue as to whether the bore dimensions were uniform from one end to another when you have no way of accurately feeling or measuring the bore dimensions as you keep firing bullets through it.
I have no doubt a custom barrel maker can push a lap through his barrels from one end to another just fine, first pass with the lap. But when you have tight and loose spots as you feel them through the lap from one end to another, that just doesn't work. Once you give that lap a bit of a tap in a loose spot, it isn't going end to end until you lap the barrel diameter out, or the lap is reduced in size from the lapping. And you keep on doing that, until the lap feels like it is giving uniform resistance from one end to the other. THEN you can go from one end to the other, with uniform resistance, in one pass. Just like the custom maker was able to do, right off the bat.
As for controllable, the laps run around 2.5" after they've been poured. But when you give the end of the lap a tap in the bore with your brass rod or whatever, the entire length of the lab does not obdurate to fill the bore. Just a small portion at the front does, as you can clearly see when you inspect your lap. If you smack your lap tight enough to obdurate the entire length of the lap in the bore, good luck moving it after that point.
The remainder of the lap is not tight in the bore, and mostly serves to keep the lap properly aligned with lands and grooves when the leading/cutting portion of the lap runs out the bore when working from the chamber end, or into the throat/ball seat when working from the muzzle end.
In other words, when you're about finished your lapping job, all the "reversing" of the lap takes place when the cutting portion of the lap is tight against thin air, not within the bore. That does take care and putting witness marks or stops on your lapping rod, so I can see why a barrel maker with barrel length to spare would not bother with that and would simply reverse the lap while it was still tight in the bore - much faster to just whack a bit off the end of the barrel rather than fuss with a lap.
If the end of the barrel got jugged from lapping, you'd be able to feel that just as the lap exited the barrel. Perhaps some of you have felt that as you finished handlapping a barrel, but I never have.
In closing, I still don't know how anyone firelapping can definitively say they've removed all the loose spots in their barrel - how can you tell without actually measuring along the length of the barrel or feeling the resistance of a lap as it is pushed up the bore?
Nor will I be lapping any Krieger, Walther, Lilja barrels anytime soon...
