JB bore paste diagnoses

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BFD
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JB bore paste diagnoses

Post by BFD » Wed Aug 29, 2018 3:26 pm

For those of you that have used JB bore paste (the white jar with blue text), what can you say about this patch? Image

This patch was soaked with Hoppes #9, then some paste was worked into it and 5-6 roundtrip strokes were taken in the bore of one of my rifles that has been giving me trouble. This was done 5 times and this is the third patch. Prior to all of this, the bore patches very clean with a dry patch, or a solvent patch, or a water-wet patch. The bore also looks clean in a bore scope.

Is this just barrel metal or is this carbon fouling?

This rifle has never fired a lubed bullet or a grease cookie of any kind. Only paper patches with fiber or LDPE wads. It still shows reamer marks after 10K rounds at least, and the throat looks great. It is lubed with NAPA ATF - F fluid which is wiped dry before firing. For a decade this has been fine until this year.

Looking for ideas about how to interpret that patch. They didn't get much better before I quit.

Woody
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Re: JB bore paste diagnoses

Post by Woody » Wed Aug 29, 2018 4:15 pm

Not a clue, but interested in your final results.

Woody

PS: I'm taking a break to get the photos I promised you.
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VBull
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Re: JB bore paste diagnoses

Post by VBull » Wed Aug 29, 2018 4:27 pm

I've used JB bore in my rifles for the last 30 years and can say you will get a black patch out of a clean barrel.
I've never tried but have to believe you'll get a black patch out of a barrel that has never been fired.
I'm not sure but think the compound has bentonite clay in it. I use it with Kroil. It does grab lead or carbon when used in a fouled bore but shows up on the patch in bright slivers.
I check my bore by pushing a patch into the muzzle and shining a light into it and looking at the grooves for "tarnish". I used to check before and after using JB but just check now after using the stuff.

I remember some "lead out" patches that used to turn black no matter how many were used. Probably the same stuff that turnes black on the patch. FM

rgchristensen
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Re: JB bore paste diagnoses

Post by rgchristensen » Wed Aug 29, 2018 5:03 pm

JB Paste -- I don't think it is bentonite, but believe it is an abrasive equally fine, tho "sharper". Probably no doubt that it is taking out barrel metal, but I will continue to use it.
CHRIS

rgchristensen
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Re: JB bore paste diagnoses

Post by rgchristensen » Wed Aug 29, 2018 5:04 pm

JB Paste -- I don't think it is bentonite, but believe it is an abrasive equally fine, tho "sharper". Probably no doubt that it is taking out barrel metal, but I will continue to use it.
CHRIS

craneman
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Re: JB bore paste diagnoses

Post by craneman » Wed Aug 29, 2018 5:14 pm

Not sure what or why but patches will always come out black using JB in my experience.

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BFD
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Re: JB bore paste diagnoses

Post by BFD » Wed Aug 29, 2018 7:06 pm

I put the same treatment to a .40=65 barrel that has never been shot. So, this is a truly virgin, unleaded barrel. The patch came out dark, almost black, but not quite like the patch I've shown above. Hmmm.

I don't know if it's clean now or not, but I will shoot it in Lodi and find out if it still wants to work. The other day, before the JB treatment but after MUCH brushing and patching, I shot it at 200 yds with a 25x Lyman and it shot reasonably well.

Kitsap
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Re: JB bore paste diagnoses

Post by Kitsap » Wed Aug 29, 2018 8:14 pm

I have used JB (both the original and micro-fine) for over 25 years. You will always get a dark patch whether on a chrome-moly or stainless barrel, new or used. You are polishing out very very small amounts of barrel steel plus whatever else is in the barrel. That can be powder, copper, or lead fouling. I do not use it for every cleaning, but when a barrel gets fouled it is one of the tools I use.

gunlaker
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Re: JB bore paste diagnoses

Post by gunlaker » Wed Aug 29, 2018 9:20 pm

Mine always come out black like that. I have a couple of new barrels here. I should try and see how the patches look after coming out of an unused barrel.

Chris.

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DAVE ROELLE
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Re: JB bore paste diagnoses

Post by DAVE ROELLE » Thu Aug 30, 2018 4:47 am

It my be possible to "wash" the patch with a solvent and examine the washed out materials under magnification and get a better idea about what the black is comprised of
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kenny s
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Re: JB bore paste diagnoses

Post by kenny s » Thu Aug 30, 2018 5:25 am

JB is an old standard for me too. dark patch is normal, heck, the stuff is dark to begin with.
you will see little slivers of shiny lead and you'll know it's working.
go light, a little goes a long way.

I use it every two or three shooting sessions of 30 rounds PP.

the lead out cloth does the same.....(keep this away from your color case, it will remove them....)

it has to be clean....not antiseptic hospital room clean.... don't overdo
Ken

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Lumpy Grits
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Re: JB bore paste diagnoses

Post by Lumpy Grits » Thu Aug 30, 2018 6:30 am

There's 2 'versions' of JB.
Both will give you the black patch. It's the jewelers rouge in the JB that does this.
When I'm done using it. I use lacquer thinner on a patch to remove this residue before applying Eezox as a preservative.
Gary
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BFD
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Re: JB bore paste diagnoses

Post by BFD » Thu Aug 30, 2018 6:33 am

Gary, how do you know when you are done? If the patches keep coming out black, what tells you that the barrel is now clean?

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Lumpy Grits
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Re: JB bore paste diagnoses

Post by Lumpy Grits » Thu Aug 30, 2018 6:39 am

You'll not see any lead or copper streaks in the lands or grooves.
Try the lacquer thinner, or even lighter fluid on a couple of patches to remove the 'film' the JB leaves, and you'll see what I mean.
It's good stuff.
What's this barrel doing, to want you to give the JB a go?
I only use the JB Bore Bright(red).
G.
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Kurt
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Re: JB bore paste diagnoses

Post by Kurt » Thu Aug 30, 2018 7:18 am

Didn't Kirk once make a post here that if JB was used in his Barrels the warranty was void ?
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