bullcoon said:
heres something l found quite a while ago about jb on one site ,how much merrit is in it l dont know for sure ?,quote gale mcmillan when someone uses jb on one of my rifles l void the warrantee! for two reasons.it dimensionally alters the barrel and not evenly,and the second reason is the barrel maker laps the barrel with a grit of lapping compound that is most effective in preventing metal fouling.then a customer polishes that finnish away with jb,l ,wouldnt be opposed to it if it were applied to a lead lap and very sparingly.it is very obvious when you look at a barrel with a bore scopes all the sharp edges are worn off the rifling.if it has jb used on it on a regular basis.as you know it is a n abrasive of about 1000 grit.as for using it on factory barrels,l will say that while it is difficult to hurt a production barrel,the thing that hurts a match barrel will do the same to a factory barrel,
This has been hashed about by Benchrest shooters for decades. The general concenus I believe is JB is not abrasive to steel but in using it proper procedures should alos be used. A good bore guide, a quality rod, etc... the method used or not used can cause more damage than JB.
Custom barrels do not have the copper fouling problems that some factory barrels have.
Lilja states:
Periodic cleaning
It is probably a good idea to use a strong copper removing solvent every 200 rounds, or so, to check the barrel for copper fouling. We do not recommend the routine use of abrasive cleaners for normal cleaning. However they can be used every 500-1000 rounds to remove the carbon build-up (caused by powder fouling) in the throat area of the barrel. To use, wrap a cotton patch around a worn out brush or a cleaning jag and liberally apply the abrasive cleaner to the patch. Short stroke the abrasive for 6" or so in the throat area and one or two full length passes through the barrel. Do not clean the barrel like this for more than 1-2 minutes.
Suggested equipment and solvents
It is important to use an action rod guide when cleaning. The guide aligns the rod with the bore and helps prevent uneven wear in the throat area. Be careful not to raise the handle end of the rod while stroking. This will put a "belly" in the rod that will wear the barrel. We suggest that plastic coated rods, like the Dewey and Parker-Hale, be used.
Our preferred cleaning solvent is Butch's Bore Shine made by BBS Industries (406-652-2495). This solvent is excellent at attacking both powder and copper fouling. We recommend it for both break-in and regular cleaning.
For occasional use only, abrasives like J-B paste, Flitz, or RemClean can be used.
Do not use a stainless steel brush in your barrel under any circumstances.
Do not apply a strong copper remover, like Sweets, on a bronze brush. It will ruin the brush and give the false indication that the barrel has copper in it.
For shooters wishing to use moly-coated bullets we do not recommend shooting more than 25 rounds or so without using the normal cleaning procedure outlined above.