Patch Lapping

[EMC45]

I did some "patch lapping" the other day. I took a .30 cal bronze bore brush (old) and wrapped with a bore patch then smeared J-B Bore Lap on it and scrubbed the bores of my Milsurps. I did the Enfield, K98, M44, M38, and M91. They all looked kinda dark to a degree. I did a prescribed number of strokes per barrel (I made the number up in my head based on my own estimation of needed cleaning) It turned out well! All the barrels turned out a lot "brighter" than they have ever been. The lands and grooves are a lot better looking. The patches came out BLACK! I followed each "treatment" with a patch of Hoppes #9 and then a dry patch then a lightly CLPed patch. Has anyone else had success with this?

[nicholst55]

With all due respect, that isn't technically 'lapping.' JB is an abrasive, but so is tooth paste. I'd consider what you did to be more polishing than lapping; I've used a lot of JB over the years, and I am a firm believer in it. I've cleaned a lot of milsurp bores with it.

Actually lapping the bore would require you to cast a lead lap and attach it to a rod, then impregnate it with an actual lapping compound and lapping the bore until the lap wears out. You would then cast a new lap and begin again, then repeat, cleaning periodically, until you were satisfied with the results.

[EMC45]

I understand it is not "technically" lapping. It did a nice job of polishing the bores for sure. The idea of really lapping the bore on many of my rifles has crossed my mind. I will see how this goes for now.

[Larry Gibson]

EMC45

I use pretty much the same method on milsurps to initially clean them and after shooting a quanity of corrose milsurp ammo. It really cleans the bullet and powder fouling out pronto. As you note it can also "shine" up a darker bore. As wit Nicholsy55 I also am a firm believer in the use of JBs in certain applications. I also Will brush the bore a few strokes with a different brush and Hoppe's, pathc it and then run a couple patches with WD40 on them to make sure all the JBs is out. You be surprised at how much comes out after a seeming dry patch that looks clean.

Larry Gibson

[EMC45]

The bores on the Mosins looked BAD! They look respectable now.

[montana_charlie]

Does anybody know what the abrasive is in the JB paste?
I recently found a home-made substitute that uses Bon Ami (feldspar) for the abrasive content.

Bon Ami is the 'Won't Scratch" answer to Comet and Ajax scouring powders.

CM

[kokomokid]

Well charlie what is the substitute as I keep bon ami for my tumbler?

[montana_charlie]

what is the substitute ?
"An excellent bore polishing paste that works as well as JB's can be made from equal parts of BonAmi™, paste wax (like Johnson & Johnson or Butchers), and light oil."
Go to http://www.frfrogspad.com/homemade.htm and scroll about halfway down the page for the instructions.
There are other ideas, too.

CM

[bkbville]

I've used the JPW/BonAmi on a couple of ugly bores - notably a carcano - and it works well. Just clean it all out.

Still, though, it's one of those bores that once I shoot it never really comes clean no matter how many patches! (I wonder if Kroil would work...)

[montana_charlie]

Prompted by this thread and the discovery of the homemade JB Paste, I did some 'felt lapping'.

I did not make a lead lap, and I didn't simply run a paste loaded patch through on a wire brush.
Instead, I punched holes in the centers of a dozen .462" x 1/8" felt wads and stacked them on a long 8-32 screw.

I left enough of the screw uncovered to run two nuts up to the wads and lock them together, and had 3/8" left to screw into my cleaning rod.

I loaded the 'felt lap' with compound, then inserted it headfirst into a 45/90 case, with the threaded end visible at the mouth. I chambered this cased lap and closed the breech.

Using a rod guide, I ran the cleaning rod in from the muzzle and screwed it onto the lap.
I pulled the rod far enough to get the lap just forward of the leade, then put a piece of tape on the rod to mark that depth so I would stay out of the chamber/throat area.

The felt wads were tight enough in the bore to make the rod follow the rifling, so I think there was enough pressure to accomplish some 'polishing'. On the other hand, running the rod in and out did not have quite as much drag as using a bronze brush.

Because this was an experiment, and not a barrel modification, I only ran the lap back and forth about ten times. Then I just jerked it out through the muzzle.

The lap is in perfect condition...ready to do it again after cleaning. The felt is white and the paste is a light tan color, but the lap came out decidedly dark.

http://i684.photobucket.com/albums/vv203/montana_charlie/FeltBarrelLap.jpg

The rifle's bore (which has some 'scabby crud' that I have been dinking with) is now polished enough that a snug patch wet with Kroil will squeal as it goes down the bore. It's nice to hear that squeal, again. I think I can get back to what I had at the start of the summer.

For the paste, I used equal amounts (by volume) of Bon Ami, JPW, and Ballistol (instructions called for a 'light oil').
A tablespoon of each didn't look like as much as I wanted, so I added a teaspoon of each.
I dumped everything in a small aluminum pan, and put it on a coffee cup warmer to melt.
While warm, I stirred it all together with a popsicle stick, then let it cool.
Just in case the oil and wax might separate, I stirred the mixture a few times while it was cooling.
I don't know if that was needed, or not, but the final product is creamy smooth with no signs of separation.

If I were to do it again, I might melt the JPW first, then add the oil. When that mixture is fully warmed, I would 'fold in' the Bon Ami.

CM