Gunsmithing JB compound

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crackerbacks

Sergeant
Full Member
Minuteman
Sep 17, 2010
459
36
SE Michigan
#1
I recently purchased a new barrel and did my normal shoot/clean breakin. The barrel has now had approx 250-300rds thru it and it still gets DIRTY after 20rds or so to the point accuracy degrades. I cleaned it as usual with shooter choise then used some JB lapping compound to try to polish the bore a bit. my question is will a patch with JB ever come out clean? I used a dozen patches and it was still coming out black, is that carbon or metal?
 
#2
Re: JB compound

They will come out black as long as JB is in the barrel. Same for IOSSO.
After I clean with JB or similar I always use some Butch's to make sure I get everything out.
BTW, you need to do some brushing with a nylon brush in there to get the JB completely out of the grooves.
 
#4
Re: JB compound


Cracker...

What are you putting the JB on? a patch?

Really the only good way to JB a bore is with the felt bore pellets available from brownells. You'll need rod stops too.

They felt pellets fit the bore so snug that a good stroking actually makes the barrel warm. I have revived countless barrels with JB and VFG felt pellets.

http://www.brownells.com/1/3/vfg-felt-pellets

No offense to Former Naval but you can't hurt a barrel with JB. it's extremely fine and breaks down really fast.

JB'ing a bore prolongs bore life.
 
#5
Re: JB compound

Thanks for the apologies, TresMon...but I have seen ANAL guys really do damage with that...might take 2000 to 3000 strokes, but, HEY...still BLACK...gotta stroke more! Especially when the rod bends and cuts the chamber mouth. Most of the time, no. As you said. You just gotta remember the outliers. Love your informative posts. Hope you get the job you are searching for. Ciao. FNP
 
#7
Re: JB compound

The JB Bore Paste is not a lapping compound. Like TresMon said, JB won't harm your barrel. Your arms will fall off before the bore paste round anything off.

The cleaning rod on the other hand will do some damage. Proper rod guides will help, but I have seen more damage done by improper cleaning than neglecting to clean the bore.
 
#9
Re: JB compound

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Casey Simpson</div><div class="ubbcode-body">cracker, you didn't tell us what kind of barrel it is, nor its age. That would help me at least. Meanwhile, arguably, Tubbs Final Finish has helped some barrels including mine. </div></div>

if you read my origional post the barrel is pretty new, only 250-300rds total. it is a blackhole 308.
 
#10
Re: JB compound

Oops! 7:50a.m. might be too early for me. Thank you for pointing that up to me.

If you read my post you will see it contained advice. Did you get my advice? You were seeking advice, right?

btw, everyone's perception of dirty varies. Whether accuracy deteriorates is the issue.
 
#11
Re: JB compound

Guys, yes you can harm a barrel with JB or Iosso, I have seen it done, we had a customer literally remove the lands from 2 barrels cleaning with it. We shoot benchrest with him and I watched him do it. I kept warning him, but he would not listen until poof no more rifling. The other problem with it is when it is polishing the barrel it will make it smooth like glass and that is bad, the barrel will keep fouling because of it and you will always have to use it to keep clean. If you a custom barrel and you feel like you have a problem and need to use it call the manufacturer first because you will typically void the warranty from most barrel makers.


Paul Tolvstad
Rock Creek Barrels
 
#12
Re: JB compound

JB will also harm your chamber, and I can't think of a reliable way to keep it out of the throat/chamber area. If your barrel doesn't shoot well, and keeps fouling badly after 250 rounds, it's a bad barrel.
 
#14
Re: JB compound

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cut rifled</div><div class="ubbcode-body">Guys, yes you can harm a barrel with JB or Iosso, I have seen it done, we had a customer literally remove the lands from 2 barrels cleaning with it. We shoot benchrest with him and I watched him do it. I kept warning him, but he would not listen until poof no more rifling. The other problem with it is when it is polishing the barrel it will make it smooth like glass and that is bad, the barrel will keep fouling because of it and you will always have to use it to keep clean. If you a custom barrel and you feel like you have a problem and need to use it call the manufacturer first because you will typically void the warranty from most barrel makers.


Paul Tolvstad
Rock Creek Barrels </div></div>

I got 1,9xx rounds out of my last factory Savage 6.5x284 barrel and it was still shooting well when I replaced it. I'm 1000 percent sure I didn't wear out the lands the two times I cleaned it with JB (10 strokes each time). Your customer has other issues than the use of JB. I can't even begin to imagine the number of strokes it would take with a polishing compond to wear away the rifling of a barrel. And two barrels??? Seriously... Everything in moderation.....
 
#15
Re: JB compound

JB paste will effect the throat. I only use jb after several hundred rounds and only when I think I have copper build up. the only way the verify is with a bore scope. but a few patches with Jb only, then your normal procedure. a lot of barrels are over cleaned.
I shot plenty of High Power and that's 88 rounds. I still only do a quick clean after the match.
 
#16
Re: JB compound

Yes moderation is good, only cleaning twice with JB won't hurt. The guy I was talking about used it every time after every target and used tight patches that he banged down the bore with the cleaning rod using the palm of his hand.
 
#18
Re: JB compound

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">Thanks for the apologies, TresMon...but I have seen ANAL guys really do damage with that...might take 2000 to 3000 strokes, but, HEY...still BLACK...gotta stroke more! Especially when the rod bends and cuts the chamber mouth. Most of the time, no. As you said. You just gotta remember the outliers. Love your informative posts. Hope you get the job you are searching for. Ciao. FNP </div></div>

Well dang. Seeing as how you can run JB down a bore that has never seen a bullet and it come out black- if a guy uses that as a gauge for when to stop JB'ing- I guess you could wear out a barrel if you truly keep at it till the jb doesn't come out black cause it wont ever happen!

I guess I forget about the folks on the extreme fringes when I'm on this here world wide interweb.

Thanks for the kind words sir.

For the Tresmon:
I have used this following regimen for years and will continue. Break in a brand new barrel nice and easy at a range session. Clean it as normal with bore solvent, then. Jb stroke it about 300ish passes. Finsih with Kroil.

Shoot and clean per normal bore solvent manner every 1 range session- 100 rounds as matches/time allows, etc.

Every 150-200 rounds it gets a good JB'ing. I got like so with the *rod* stroke: in 6" , back out, in 12" & out, in all the way to muzzle & all the way back out. This emphasizes polishing the throat area mostly (to keep fire checking smooth and snag free) but also nourishes the whole bore in a loving manner.

The result: My low budget builds normally will shoot .25moa @ 400yards, and When I say how many rounds I get out of a bore, folks usually raise an eyebrow and give me a "yeah right" look....

* * I use a carbon fiber rod. I dont even trust "coated" steel rods in my bores because I have had the coating come off on me or be sliced off by the crown of the muzzle. I always use a tight precision machined bore guides- none of this floppy universal stuff, etc. I subscribe to the "cleaning rods have worn out far more barrels than bullets have" theorim..
 
#23
Re: JB compound

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shoot4fun</div><div class="ubbcode-body">IMHO, Lucas are the very best.
</div></div>

This.
 
#25
Re: JB compound

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cut rifled</div><div class="ubbcode-body">Guys, yes you can harm a barrel with JB or Iosso, I have seen it done, we had a customer literally remove the lands from 2 barrels cleaning with it. We shoot benchrest with him and I watched him do it. I kept warning him, but he would not listen until poof no more rifling. The other problem with it is when it is polishing the barrel it will make it smooth like glass and that is bad, the barrel will keep fouling because of it and you will always have to use it to keep clean. If you a custom barrel and you feel like you have a problem and need to use it call the manufacturer first because you will typically void the warranty from most barrel makers.


Paul Tolvstad
Rock Creek Barrels </div></div>

Agreed!

I even had one customer how put a patch on the end of a wooden dowel attached to his CORDLESS DRILL! Take it easy. If it takes more than 2 fouling shoots to return to your POA, you are cleaning too much. "But I can still see copper and fouling." So? Is it effecting accuracy? No, Then don't worry about it. Pay attention to the target first, patches second.

"You need a license to drive a car, but any idiot can buy a borescope" Gunsmith that prefers to stay anonymous.
 
#26
Re: JB compound

As an aside; I seriously doubt that 20rd can cause enough fouling to seriously degrade accuracy. I believe the OP about the accuracy degrading, but I'm not so convinced that the issue is about fouling.

I would suggest some minor load fiddling, to see if the load's best suited to the way the rifle is being employed. It may be that the load does not like being fired out of a warmed up, prefouled barrel. If that's how the rifle is being employed, that's how the loads need to be tested for proper development results.

Greg
 
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