Home Forums Hunting & Shooting Ask The Gunwriters Will JB Bore paste dammage a barrel?

The standard JB breaks down as mentioned but IIRC it is about 1600-2000grit, the red polish is even finer, about 3000grit per a brownells tech. I have both but cant really see a difference in either when it came to cleaning down to bare steel to apply UBC.

they seemed to work in a .270 I own. I have bore pasted a number of times, then bore polished, as well. At the end the gun seems to shoot much better than it did when I bought it, but that could be any number of things, it does however foul very little.

What is red bore polish?

The red is another polishing compound marketed by Brownells under the JB logo. They recommend its use after using the original JB for a "mirror" polish. I have used after 1000grit wet/dry paper on knife blades and it does take the finish to a brighter finish.

http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=1161&title=J-B~%20BORE%20BRIGHT

Rem clean and JB are pretty much the same except Rem cleans abrasive is in a oil suspension VS JB in grease. Both are good products and will not damage your bore Iosso paste is also very good especially in the throat to remove hard powder fouling.

Lefty C

Your arm would fall off before JB removed that burr

Some 3m scothch bright pad on a wooden doel spun lightly on a lathe or drill will take care of the burr...just dont go into the throat.

Lefty C

I have tried almost every bore cleaner, paste, and copper remover on the market, and even some that arent. After I bought a borescope, the real testing started.

The best barrel cleaner I found was the Red JB Bore-Brite, on a patch, wrapped around a nylon brush. It is usually easier to get this to work with a brush one bore size down from what you are cleaning.

I roll the patch around the brush and apply the JB to it. Then push it into the bore guide, then insert into the action. Be sure to use a stop on the rod to keep it from exiting the bore. I use 25 strokes in the first 10 inches in the barrel to get the heavy carbon out, and then 25 more full length strokes to finish the barrel. This removes every last bit of carbon and copper from my barrels.

Most of my rifles drop off in accuracy before 50 rounds, and need to be cleaned, with the exception being my Tikka .308. It will go over 300 before the carbon in the throat needs removed, and then it goes right back to shooting great.

In all honesty, I havent found the Red to work better than the Brown, but being a finer grit paste makes me feel better about using it.

If the burr is large it should be removed with a neck reamer, if it is more of a rough spot you can remove it with 0000 steelwool on a delron rod in a drill. 0000 steelwool doesn't remove any metal from the chamber it burnishes them nicely.

The difference in coefficient of friction between a polished chamber and an unpolished chamber is not enough to increase bolt thrust. If someone were to get crazy polishing a chamber and that chamber was already at max headspace, a dangerous condition could result.

Coefficient of friction study: http://www.varmintal.com/a243z.htm

I went to the link and read the test. Not being an engineer, I really did not understand all that I read, but I was able to compare the figures of bolt thrust.

One piece of information that I did not see was the taper of the case, and the effect the taper has on the case gripping the case walls. With my limited engineering knowledge, I was unable to determine if case taper was given consideration in the calculations.

Also, sometimes I am a little leery of calculations when substituted for actual nuts and bolts testing under field conditions.

A taper will grip the walls where a straight cylender will not. That is how a Morse taper works, to hold a tool in a lathe head stock or tail stock.

Lubricating the Morse taper will reduce the holding ability of the tool shank.

The graphs and charts tests included a similiated highly polished chamber and a greased case, but with very little increased thrust on the bolt face.

I disagree. In my experience, leaving a very slight film of oil in the chamber after cleaning allows the case to stretch so much that when loading to near maximum pressures, the bolt is very difficult to open. This is with both a smooth and rough chamber.

I usually polish my chambers down to 400 grit.

With the same loads and a clean, dry chamber and a clean, dry case, this doesn't happen.

I can offer no explanation, other than the taper of the case, and the possibly that the greased case allowed the brass to lengthen past the elasticity limit. The above causes are only guesses, but it a fact that a greased case will result in harder bolt lift.

It is also a guess, but I think a dry, highly polished chamber would allow case stretching, although not as much as a lubricated case.

I purchased a Ruger .243 MKII Target rifle for very little money eight years ago. The owner said he took the rifle on a a couple prairie dog hunts and he said the barrel was shot out. I used JBs both kinds over a few weeks and a few hundred patches. My effort resulted in a rifle that will shoot true .5 moa. I have used JB bore paste on most of my rifles with positive results.