JB's Bore Paste vs Bore Lapping
- Thread starter hooligan1
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Dfariswheel
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No.
When you lap a barrel, the lap is cast in the bore and is a close fit with the corners of the lands and grooves and makes full contact with the grooves.
When you use JB Bore Paste, the patch doesn't make perfect contact and would probably round off the sharp top edges of the lands before it lapped everything else. This would probably take years of use.
JB will help shine up a bore or keep it shiny but it's not intended to be a lapping compound.
A better option would probably be to use one of the fire-lapping kits or use one of the break-in processes of shooting a round and cleaning for a certain number of rounds.
When you lap a barrel, the lap is cast in the bore and is a close fit with the corners of the lands and grooves and makes full contact with the grooves.
When you use JB Bore Paste, the patch doesn't make perfect contact and would probably round off the sharp top edges of the lands before it lapped everything else. This would probably take years of use.
JB will help shine up a bore or keep it shiny but it's not intended to be a lapping compound.
A better option would probably be to use one of the fire-lapping kits or use one of the break-in processes of shooting a round and cleaning for a certain number of rounds.
I've taken to using JB Bore Compound in place of conventional break-in procedures. I first got the idea reading Varmint Al's site. He cleans the bore and gets out the JB and gets about 50 full strokes in with it and calls it done. He described one gun in which that proved inadequate and he went to a second treatment with Flitz.
The way I do it is more aggressive. I've firelapped enough bores now to have lost my fear of the judicious use of a bit of abrasive in a bore. I fire just one shot, use Boretech Eliminator to remove fouling and copper (I used to use Sweet's 7.62, then Butches Bore Shine — any copper removing bore solvent will work — but Eliminator is faster, odorless and non-toxic and has enough water to handle accidental use of corrosive primers). After there is no copper left, then I apply the JB. I always do this working from the breech end with a bore guide in place to keep the chamber minimally dirtied. I run the patch in and go back and forth in short strokes while inching the patch down the barrel. By the time it gets to the muzzle I've got 20 or 30 short strokes in and usually add a long stroke or two. The idea is the abrasive is most fresh near the breech where the most fouling is normally left.
After doing that for 20 rounds, you should notice the barrel cleans more easily. It won't clean the way a firelapped barrel does (that's a dramatic difference) but it should be about as good as commercial barrels get without lapping. I no longer mess with the break-in procedures that have you simply clean with a solvent and brush between each round, then, after 20 or so, clean every three, then later every five rounds and so on. They can use up 100 rounds and, in really rough bores, often don't seem to make a whit of difference. My first Garand's barrel was like that. The JB will positively smooth the surface and dull sharp edges that grab copper. If it fails to make the gun as easy to clean as you think you want it, then you need to look at firelapping. Hand lapping involves more work and skill, but if you are good at it, it will make the bore very uniform.
Incidentally, when I got tired of watching the Garands accuracy drop off during the slow fire stage of the National Match Course (between rounds 30 and 50), then taking all night with Sweet's to clean out, I finally did buy a NECO kit and firelap it. Based on measuring the number of patches required to complete cleaning, the improvement was about 6:1. No more accuracy loss even during an 80 round + sighters NRA Service Rifle match.
The way I do it is more aggressive. I've firelapped enough bores now to have lost my fear of the judicious use of a bit of abrasive in a bore. I fire just one shot, use Boretech Eliminator to remove fouling and copper (I used to use Sweet's 7.62, then Butches Bore Shine — any copper removing bore solvent will work — but Eliminator is faster, odorless and non-toxic and has enough water to handle accidental use of corrosive primers). After there is no copper left, then I apply the JB. I always do this working from the breech end with a bore guide in place to keep the chamber minimally dirtied. I run the patch in and go back and forth in short strokes while inching the patch down the barrel. By the time it gets to the muzzle I've got 20 or 30 short strokes in and usually add a long stroke or two. The idea is the abrasive is most fresh near the breech where the most fouling is normally left.
After doing that for 20 rounds, you should notice the barrel cleans more easily. It won't clean the way a firelapped barrel does (that's a dramatic difference) but it should be about as good as commercial barrels get without lapping. I no longer mess with the break-in procedures that have you simply clean with a solvent and brush between each round, then, after 20 or so, clean every three, then later every five rounds and so on. They can use up 100 rounds and, in really rough bores, often don't seem to make a whit of difference. My first Garand's barrel was like that. The JB will positively smooth the surface and dull sharp edges that grab copper. If it fails to make the gun as easy to clean as you think you want it, then you need to look at firelapping. Hand lapping involves more work and skill, but if you are good at it, it will make the bore very uniform.
Incidentally, when I got tired of watching the Garands accuracy drop off during the slow fire stage of the National Match Course (between rounds 30 and 50), then taking all night with Sweet's to clean out, I finally did buy a NECO kit and firelap it. Based on measuring the number of patches required to complete cleaning, the improvement was about 6:1. No more accuracy loss even during an 80 round + sighters NRA Service Rifle match.
JB Bore paste is just for smoothing out the rough spots, it is not for precision lapping. Fire lapping is a good option, but if you really need to polish your rifle's bore that much, you could probably justify replacing the barrel altogether. A new barrel, a few break-in shots, clean well, and there you are shooting better than ever.
I have no "bad barrel" right now Scorch thanks for the reply though. The Rem 700 ADL I gave my son, has some bad pitting, due to the previous owner "testing it out", when he traded for it. Him and his brother shot some older military ammo through it and knew nothing of how to clean it afterwards, after I pointed it out to them and that maybe it was too late to fix the pitting, I traded him out of it for a song, basically. This rifle has always shot very well despite. Just yesterday my son was grouping the old rifle at about 1/2 to 3/4's of an inch at 100 yds. I wished I had a dollar for every deer I have taken with that old rifle.
I'm sure that he'll just keep shooting it until its completely worn out, and most importantly Scorch is the fact that the boy has the utmost confidence in his rifle!
Getting back to the subject though, I was interested in what kind of polishing I would get from using the bore paste over a period of years? And if you say there's no real underlying benefit, I trust your wisdom on this matter!!
I'm sure that he'll just keep shooting it until its completely worn out, and most importantly Scorch is the fact that the boy has the utmost confidence in his rifle! Getting back to the subject though, I was interested in what kind of polishing I would get from using the bore paste over a period of years? And if you say there's no real underlying benefit, I trust your wisdom on this matter!!