What exactly is Firelappin for?

[qajaq59]

I read recently about a firelapping kit and I assume it is used to polish the barrel. However, I have no idea when you would use it, nor what the results would be. Could someone just sort of run thru exactly why you would use it? And does it take the edges off the rifling?
Thanks Qajaq

[handyrandyrc]

Boy, I've only heard about it myself, so this is truly a case of blind leading the blind. I _THINK_ the "kit" comes with bullets with different coarseness of grit impregnated in them. You follow the directions, load them to their recommended specifications for your firearm, and fire them in the order specified. It's supposed to help take out any "tight spots" in the barrel and smooths things out a bit.

[KCSO]

Fire lapping is the lazy mans way to trying to polish a barrel to temove burrs and cutter roughness. I have never resorted to this as I prefer to cast a lap in the bore and do the job right. I also have to agree with Pope when he said "If yo have to lap a bore yo didn't build it right in the first place". I have never lapped the bore on a properly made hight quality barrel.

If you check Brownell's web site they have the kits and in the articles section they have an instruction page. Basicly you are using grit and gunpowder to try an smooth out the bore you roll the bullets in grit fire clean and do it agan until the bore smoots up. At least this is the idea. If I lap a bore I prefer to do it by hand and feel the job through ever step of the way. Fire lapping has always seem to me about like shooting sand down the tube and hoping things will get better.

[qajaq59]

Fire lapping has always seem to me about like shooting sand down the tube and hoping things will get better.

Now I'd say that is a pretty clear image. I guess I don't need to know much more then that.

[duke76]

Well then what is the procedure for cast lapping a bore?

[carpetman]

Firelapping is controlled burning of an area so it wont catch on fire at a bad time.

[Parson]

Having used fire lapping for over thirty years I think I know a little bit about the subject and I am prejudiced in my views. The first thing I would say is if your gun shoots well and is not subject to heavy leading or copper fouling dont do it. Many barrels have been damaged by over zealus firelapping. You can use cast or jacketed but the cast has a tendancy to take out the throat if over done. I do not like the Neco kit as they start with way too course of grit, I would recomment LBT if he still sells it. Hand lapping is not what some crack it up to be on an existing barrel. When you stroke the lapp back and forth, stopping at the breach and muzzel you have two different rates of lapping. One at the two ends and something else in the middle. Hand lapping is good for a new uncut to length barrels. Many revolver barrels are tight at the breach end. Not all agree as to why. Some say because they thread with a die instead a lathe others insist it happens when the barrel is tightened against the frame, I dont know but I have measured enough of them to know it is a problem and affects the accuracy, especially with cast bullets, fire lapping is the only practical way to correct this problem. With rifles very seldom have I seen an increase in accuracy after fire lapping but I have seen many cut copper fouling by half or more (twice as many shots between cleaning). If you are still interested, again I would recomend you get in touch with LBT

[mhb]

Is a last resort measure to be taken only when it has been determined that a barrel will not shoot properly due to surface finish problems in the bore. It is rough-and-ready at best, and the best outcome that can be hoped for is some measureable improvement in accuracy or an increase in the number of shots which can be fired before accuracy is degraded due to metal fouling. On the other hand, a basically good barrel may not be improved at all, or actually damaged.
Lapping is a useful tool to the barrel maker (and lapping of a barrel should ONLY be done before the barrel is fitted and chambered, not afterward). I've made many hundreds of barrels, and every one of them has been hand-lapped. This is not due to lack of care in manufacture, but because every method of barrel manufacture is subject to surface-finish artefacts left in the bore either as a consequence of reaming the bore, rifling it, or both. Further, it is customary to shorten such a barrel blank about an inch at breech and muzzle after lapping, because there is inevitably more uncontrolled lapping action at the ends of the barrel where the lap passes in-and-out, and where the abrasive is charged onto the lap.
For these reasons, I advise considerable caution in approaching firelapping - it is not a panacea and can actually degrade, rather than improve a barrel which is not really a bad one.
mhb - Mike

[carelesslove]

I bought one of the LBT "kits", for a S&W Model 24-3 that had a tight spot in the bore (where it screwed into the frame) and a rough forcing cone.

The firelapping kit basically consists of a small container of lapping compound (fluid + grit), and a pair of lapping plates that areboth hardened and polished. Using a medium-soft cast bullet, roll the bullet between the plates with an excess of the compound. This produces a bullet with abrasive bands - rough to the touch, but not too much so.

The kit's instructions recommend loading these into cases with a light charge of powder, making sure to check for a barrel obstruction after every round.

I followed the instructions to the letter and 'lo & behold, the tight spot in the barrel literally went away, with no visible "rounding" of the rifling. However, the abrasive compound neatly and brightly polished the entrance to the forcing cone - JUST ON ONE SIDE !!!!

I then boxed up the gun and sent it back to S&W for a factory repair to correct the timing / alignment.

I am certain that the LBT folks know what they are doing and the firelapping is a viable process, if their instructions are followed. My revolver was too screwed up to fix with firelapping only.

I hope this is usable information.

Thanks, carelesslove