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Posted: 5/30/2009 4:10:10 AM EDT
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I'm getting ready for a prairie dog shoot later this month and decided to give my 20" RRA chrome moly heavy barreled AR a thorough bore cleaning. I followed my normal bore cleaning method as follows.
I applied Break Free FBC and let it sit for 15-20 minutes and pushed a dry patch through the bore with a pointed jag. As expected, there was very little crud on the patch, mostly light gray with a very slight blue/green tint. For the sake of thoroughness, I then used a nylon brush with Butch's Bore Shine, which does contain some ammonia for copper removal. I ran the brush both ways through the bore about 10 strokes and waited about 15-20 minutes again and pushed a couple dry patches through again, finding very little residue. The last patch came out nearly white.(i've never had a patch come out with no tint on it at all) Just for the hell of it and having read it recommended on other precision rifle sites, I decided to run some JB through the bore. I put a patch on my pointed jag and applied some JB per recommendations on the JB container. I ran the JB patch 10 complete strokes through the bore both ways and the patch came out completely black. What is this crap that the JB removed that the other bore cleaners didn't touch? Prior to using the JB, the bore looked like a mirror. As well, when pushing patches through, I couldn't feel any spots that felt rough at all. I find it hard to imagine that there was still carbon fouling in the bore that the FBC and Butch's didn't remove, but I have no idea what else it could possibly be. Any ideas? |
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Quoted:
I'm getting ready for a prairie dog shoot later this month and decided to give my 20" RRA chrome moly heavy barreled AR a thorough bore cleaning. I followed my normal bore cleaning method as follows. I applied Break Free FBC and let it sit for 15-20 minutes and pushed a dry patch through the bore with a pointed jag. As expected, there was very little crud on the patch, mostly light gray with a very slight blue/green tint. For the sake of thoroughness, I then used a nylon brush with Butch's Bore Shine, which does contain some ammonia for copper removal. I ran the brush both ways through the bore about 10 strokes and waited about 15-20 minutes again and pushed a couple dry patches through again, finding very little residue. The last patch came out nearly white.(i've never had a patch come out with no tint on it at all) Just for the hell of it and having read it recommended on other precision rifle sites, I decided to run some JB through the bore. I put a patch on my pointed jag and applied some JB per recommendations on the JB container. I ran the JB patch 10 complete strokes through the bore both ways and the patch came out completely black. What is this crap that the JB removed that the other bore cleaners didn't touch? Prior to using the JB, the bore looked like a mirror. As well, when pushing patches through, I couldn't feel any spots that felt rough at all. I find it hard to imagine that there was still carbon fouling in the bore that the FBC and Butch's didn't remove, but I have no idea what else it could possibly be. Any ideas? IIRC JB Bore Bright has some abrasive in it. I'm guessing the black is a very slight amount of metal (which is not neccesarily a bad thing as long as it is a very small amount). Did you use the Non-embedding bore paste or the Bore Bright? (the first is more aggresive IIRC). Some people use the Bore paste followed by the Bore Bright as a way to sort of Lap the barrel. As long as you do not do this all the time you should be fine. J- |
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Quoted:
What is this crap that the JB removed that the other bore cleaners didn't touch? The barrel material itself perhaps? As you noticed, the FBC did a pretty good job by itself. That was confirmed when you went behind the FBC with Butches, which I’ve never personally used, but understand is a fairly aggressive copper solvent. Right there, I personally would have left well enough alone. The JB, which again I’ve never personally used, but from what I’ve read, is more of an abrasive paste. I imagine since there was no heavy fowling for the JB to remove, the black patch was due to the JB polishing the barrel itself. ETA: Let this be a testimony to the effectiveness of BF FBC! 
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| You guys might be right. The black residue looked similar to what you get when using metal polish on something like silver. I was surprised to find the patch come out black when this rifle can fire quite a few rounds without much fouling. Anyway, I guess the bore is clean now. |
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Quoted:
You guys might be right. The black residue looked similar to what you get when using metal polish on something like silver. I was surprised to find the patch come out black when this rifle can fire quite a few rounds without much fouling. Anyway, I guess the bore is clean now. As I edited above to add: Let this be a testimony to the effectiveness of BF FBC! |
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I believe that the JB is turning that color just from use. I thought the same thing once. I ran a patch over a clean machined piece of metal. The patch turned the same color and it didn't scratch the metal. It's just the JB turning color after use.
It does get a bore squeeky clean with lots less work. |
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Quoted:
I believe that the JB is turning that color just from use. I thought the same thing once. I ran a patch over a clean machined piece of metal. The patch turned the same color and it didn't scratch the metal. It's just the JB turning color after use. It does get a bore squeeky clean with lots less work. If the patch is turning black, there is metal being removed. The surface might not show signs of scratching, but the surface is being polished. That is the reason why the patch is black. A good example would be polishing a block of steel with a rag and some Brasso. The rag turns black because of the material being removed through the polishing action. |
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Quoted:
Quoted:
I believe that the JB is turning that color just from use. I thought the same thing once. I ran a patch over a clean machined piece of metal. The patch turned the same color and it didn't scratch the metal. It's just the JB turning color after use. It does get a bore squeeky clean with lots less work. If the patch is turning black, there is metal being removed. The surface might not show signs of scratching, but the surface is being polished. That is the reason why the patch is black. A good example would be polishing a block of steel with a rag and some Brasso. The rag turns black because of the material being removed through the polishing action. yep exactly what Quib said. its the metal not the JB turning color from use. Think about taking a rough cast metal part and polishing it to a high shine. There is no scratchs but the polishing does remove metal. Otherwise how would polishing smooth out that rough cast part? J- |
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I use JB on my Glock barrels once in a while, and always marvel at the black patches - but I can also say that I have had them come out brown (the original color) if you do it several times. I'm not entirely sure what it's removing, but it doesn't do it forever. I've found that running JBs thru the Glock barrels maybe once every 3-4 outings (3-500 rounds total) works well, and keeps 'em quite clean & shiny.
I don't use JBs on my ARs much because I'm concerned it will get up into the gas system. I did use it to get really bad leading/crud out of my 10-22 barrel (a decade of poor cleaning) and to my amazement, after about 20 repetitions, those started coming out clean & brown, too. |
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No, not when used as directed. It's especially useful for cleaning out the first few inches of bore at the chamber end, works nicely on carbon.
BR shooters use it mixed w/Kroil penetrating oil. If it were harmful to bores, I doubt it would used by that group,because if there's anyone who's anal about bore care, it's the BR crowd. There are other effective products, but I wouldn't be concerned about using JB. |
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If all I had was JB, USP, Iosso, or Remclean I would not fret one millionth of an iota.
My practice is to remove most fouling with solvents. If I get enough metal fouling (like after 1500 rds FA) l use paste after the chemicals stop leaving green on patches. There is no faster route than abrasives - and that includes strong NH3+ and electrolytic methods. Takes all of maybe 10 seconds. Use bore guide. Be careful not to flex the rod. Be careful not to drag crud back from the muzzle. Again, benchresters would not use abrasives/Kroil if it chewed up barrels. Even 1/10 MOA accuracy loss is a major heartache to a benchrester. I wouldn't notice 1/10 MOA if it hit me on the head. BTW, Hartley is correct that the patches don't stay black. After 1500 rds FA a third patch with paste will look like I didn't run it through the bore. Sam |
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http://www.twincityrodandgun.com/PDF%20files/Rifle%20Bore%20Lapping.pdf
A nice write up on rifle bore lapping/polishing by Fred Bohl 26 April 2005 using J-B. Page 5 is the Tools & Materials list. |
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