Bore lapping by hand


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BsChoy
March 26, 2008, 11:39 PM
I have read all the stuff about lapping a bore about how bad it is for the bore and what not but I have a savage that has railroad track like machine marks in the barrel and I wanted to try either JB bore compound or the Wheeler lapping system (not the firelapping type) to try and remove the marks. Any tips or experience I would like to hear!

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Ifishsum
March 27, 2008, 04:11 AM
With JB paste, stir it well and use a jag and a tight fitting patch on a quality rod with a handle that rotates freely under pressure. Use a bore guide that seals off the chamber if possible, but use a guide for sure. I do about 15-20 strokes per patch, after that your patch will probably be starting to wear holes through. Every few patches I run a clean patch and check my progress.

koginam
March 27, 2008, 10:59 AM
If the scraches are deep it will take a lot of lapping with JB to smooth it out.
I mainly do new barrel blanks but I have done many many finished barrels, so when I get a blank I cut off to length I keep the cut off piece and use it as a mold for the lead lap. If you contact a gunsmith they may have a pices of barrel you can use. I then take a threaded one piece rod and put on a tight fitting cleaning patch and run it down the barrel, where I feel it get tight I make a mark on the rod with a marking pin then when the patch feels loose again I make another mark on the rod, I do this the whole length of the barrel, now I lay the rod on top of the barrel and mark the barrel with the start and end of the tight places. I heat up the piece of barrel I saved with a torch and then before it cools I put in a jag and pour in the lead to make the lap, as it cools the lead lap can be pushed out, I make 5 to 7 laps.
I place a little rubbing compound on a piece of tempered glass and place the lap in it then with another piece of glass I roil the lap back and forth until the lap is coated. now I place the lap into the barrel and move it close to the mark on the rod I push the lap back and forth between the marks after 6 to 8 passes I make a couple long passes, 2 to 4 inches past the marks,to even out the polishing. After 30 or so passes I reapply compound and and continue, if the lap feels loose I use a new one, then I go to 400 grit and finish with Simichrome.

rbernie
March 27, 2008, 12:07 PM
What little I've read suggested that hand-lapping tends to overly wear the ends of the bore no matter how you try to keep the strokes and pressure consistent. As a result, everyone that hand-laps a custom barrel chops off about an inch of each end to remove this irregularity.

I'd leave the barrel along if it shoots well enough. If you really feel compelled to do something about the crosshatching, I'd probably recommend fire-lapping over hand-lapping.

But I may be full of crap, too.

BsChoy
March 27, 2008, 08:34 PM
thanks fellas much appreciated

highlander 5
March 28, 2008, 08:39 PM
I've fire lapped several pistols using both the Wheeler kit and the LBT version sold by Veral Smith both work very well the Wheeler kit is quicker as it takes fewer shots to work. I used the lapping compound from LBT with excellent results.
My Ruger Bisley had a very tight throat and a very rough barrel it took about 100 rds embedded with compound but the bore is like a mirror and very,very smooth and .4515 in dia. BTW JB bore paste may not be abrasive enough to lap to scratches,check with Brownell's as they are the manufacturer of JB as to its use

BsChoy
March 29, 2008, 10:23 AM
Think I'm going to irder the Wheeler lapping kit and have at it...steady as she goes till I can't see those marks anymore

koginam
March 29, 2008, 10:51 PM
If you fire lap follow the directions faithfully, I have used fire lapping many times and I have had no problems but I read the directions and follow them each time.

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