I have used JB Bore paste a few times over the years. It does a great job for cleaning tough jobs. My question is, will it work to smooth up a rough factory bore? Can you use it to much?

While JB is fine to remove copper, I don't think it's erosive enough to smoothen a rough bore. If it was, it might be harmfull to a good bore...

quote:

Originally posted by Andre Mertens:
While JB is fine to remove copper, I don't think it's erosive enough to smoothen a rough bore. If it was, it might be harmfull to a good bore...

Agree.

I love JB.

I mix it with gun oil so it becomes running, and makes it easier to dip the cleaning pads in.

Great for cleaning stubborn barrels.

Gale McMillan was not a fan of barrel break in and used to void the warranty on his rifle barrels if his customers used JBs to clean them. He thought it rounded the sharp edges on the rifling.

If you click the link below to 6MMBR you will find an excerpt from him. Then scroll down and click the lower link on the bottom of the page labeled "More from Gale McMillan: http://www.snipercountry..." for more info.


http://www.6mmbr.com/gailmcmbreakin.html

I use it when all else fails. Great stuff!
Instead of applying it to a patch, I dip a nylon brush in the stuff.

JB is non abrasive.....let me change that to zero abrasive

For all intents and purpose it is a cleaner and it seems to work

I have spent years on the bench finish polishing the molding areas of injection mold cavities and cores using every abrasive money can buy

From simple 220 and 320 draw polish all the way up to ultra high end #2 diamond or #1 optical quality mirror diamond on hardend H13....S7....P-20....4140 and the list goes on

You can stroke a patch covered in JB through a barrel until it hair lips every cow in Texas and trust me....

You will do more harm to your bore with the rod and jag....not the Jb paste

It will not lapp or smooth the ID of a barrel

quote:

Originally posted by Fuchs:
I use it when all else fails. Great stuff!
Instead of applying it to a patch, I dip a nylon brush in the stuff.

I use this method as well. Great forgetting lead out of a pistol barrel.

I don't have a bore scope, but Frank White of Compass Lake Engineering does. Frank claimed that impacted debris accumulates in the throat and chemicals and brushing won't remove the stuff. Instead, a more aggressive mechanical means had to be used. There were examples of barrels that came into the shop that were not worn out but simply had dirty throats. These barrels started shooting well once cleaned out with JB.

I have waffled about when to use JB. I have cleaned well used barrels with JB only to experience big zero changes until the barrel fouled back in. So, I am getting to be of the opinion that use of JB is something that should done sparingly . It is an abrasive and barrels are soft.

If the rifling is gone, no cleaning technique can restore accuracy.

Take a ground flat piece of stainless steel or 4140

Get a rag and rub a spot smack dab in the middle with JB for as long as you want

After 3 or 4 jars....I bet your not even .001 deep


Now that being said.....is it a good bore cleaner?

It is a great bore cleaner and I use it

IIRC, JB consists of "rendered" alumiminium oxide or some such. The rendered means that it is non-impacting on steel.

It is mildly abrasive - on copper, gilding metal etc and so it is very good for cleaning barrel bores. Since it does not impact on steel, it does not scratch the bore or ware out the bore of barrel.

On the other hand you will run into trouble if you use any of the impacting type abrasive paste like Autosol or similar paint shop stuff. That will impact on steel and cause scratches, rough edges etc.

I believe JB is garnet powder abrasive...

quote:

Originally posted by ted thorn:
JB is non abrasive.....let me change that to zero abrasive
For all intents and purpose it is a cleaner and it seems to work
I have spent years on the bench finish polishing the molding areas of injection mold cavities and cores using every abrasive money can buy

From simple 220 and 320 draw polish all the way up to ultra high end #2 diamond or #1 optical quality mirror diamond on hardend H13....S7....P-20....4140 and the list goes on

You can stroke a patch covered in JB through a barrel until it hair lips every cow in Texas and trust me....

You will do more harm to your bore with the rod and jag....not the Jb paste

It will not lapp or smooth the ID of a barrel

Though I agree with most of the above--
JB is mildly abrasive-
That abrasive is listed in the MSDS:

"ALMANDINE AND PYROPE GARNET"

which are gemstones - and -abraisives--

though finely ground-(powdered)
it is still an abrasive

I use several different micron sizes of diamond compounds finishing #1 #2 polish jobs

Diamond paste is also powered by theses so called gemstones

That being said.....you can not lapp nor harm a barrel with JB or for that matter yellow, orange or even red diamond compound from Congress

As stated, doubt that JB Compound would do much for smoothing out a "rough" bore for it is not that aggressive as an abrasive. I consider it a "polish" and cleaning material. Shot Long Range competition for several years and used all manner of barrels and after 4 matches(60-75rnds./match) used JB in addition to normal cleaning process. Caliber 308 and barrels saw some 3000rnds.+ through them before changing out and accuracy did not suffer due to using JB compound, but they were clean. Quite a few competitors used JB compound as well.
Very few sporting rifles will ever see that many rounds down the barrel in a two year span of time and do not use JB for those rifles, just normal cleaning techniques, HOPPES 9, Shooters Choice, etc.
Many years ago "old timers" shooting match Springfield '03's would place muzzle in bucket of water and apply generous amounts of "Bon Ami"(kitchen sink cleaner) in the bore and using bore mop would scrub the bore repeatedly. The motto of that cleaner was "barely scratch the surface," telling that it was an abrasive, but just very mild. Sounds rude and crude, but it apparently worked in those days.

Its good stuff, ever so slightly abrasive and not to be overused..We tend to over clean our guns in the good ole USA..