JB Bore Compound

[chino1969]

I'm breaking in a brand new match grade barrel using the shoot one, clean, etc. After cleaning with Mercury Quicksilver to get the carbon, BMG 50 for the copper and fouling, then a few sprays of break cleaning fluid, followed by some dry patches to remove all solvent. Upon examination with a borescope, I saw some carbon around the neck junction/leade transition. A little JB on a round felt 6mm. cleaning felt, short stroked in the neck area, made short work of the carbon as well as a little residual fouling. I've use JB & JB Bore Brite for any stubborn fouling and after every 200 rounds once the barrel is broken in. This was before I acquired a bore scope. The bore scope examination now dictates my cleaning regimen and I will alter to suit. The question I have for all of the seasoned shooters on this page is as follows:
1) How often do you use JB?
2) Is there any risk in increasing bore diameter with the use of JB?
3) Does anyone know of or has done their own experimentation with how often to use JB or if too much is bad?
Thanx in advance,
Chino69

 

[tightneck]

As far as JB goes, I use it when I feel the bore needs it. Some barrels need it more often than others, especially older barrels. I dont think it hurts the bore in any way. I've pretty much given up on barrel break-in. It seems no matter what method I have used, a barrel is either gonna copper foul or its not. I have two new shilens recently chambered up and neither of them has produce a blue patch yet,50BMG). Neither were broken in, just put the first 20-30 shots downrange and then cleaned. One has 200 rounds in it, the other about 350. I have a Kreiger that I did break in with 1 shot then clean and so on until the patches stopped coming out blue. Now with 400 rounds, it copper fouls very badly.

 

[chino1969]

tightneck,
I know what you mean by questioning whether barrel break-in has any merit or not. According to Gale McMillan it's a bunch of B.S. created by barrel makers to sell more barrels. I do know that a reamer will leave tiny circumferential machine marks in the freebore area before the reamer touches the rifling. The theory with breaking a barrel in is that you are removing these tiny ridges. If that is the theory, those ridges will be removed by firing bullets, regardless. So again, I think it's one of those conventions that is followed by alot of shooters because it can't really hurt the bore. A well known gunsmith just put together a 6mmBR for a friend of mine with a Krieger barrel. When asked about barrel break-in, the gunsmith replied: 'It is not necessary but if you feel better doing it, then do it'.
Chino69

 

[steveyrock]

I used JB when I shot moly coated bullets and then only every 100 rounds.I find no need to use it now since I shoot naked bullets because my barrels clean up very good with solvents and lite brushing.I have learned to let the solvents do there job by letting them soak in the barrel for 15 minutes or more before dry patching or brushing.I also think a little dirt in the barrel is a good thing.JB is better kept for use in neglected hunting rifle barrels and caked up rimfire bores. With naked bullets I would not use JB in a match grade barrel unless solvents are not doing the job.

 

[chino1969]

steveyrock,
Thanx for the reply. I used JB when the normal solvents would not do the trick, even after letting them soak for 20 to 30 minutes. I use a borescope now when I finish cleaning and look carefully at the throat/freebore area. If I see carbon, I take it out with JB. That is after using Mercury Quicksilver and BMG50.
Chino69

 

[steveyrock]

My Broughton takes 3 to 4 shots to settle down after a thorough cleaning then it will hold good accuracy for another 30 rounds or so before I see a need to brush it out,This barrel does not copper foul much at all if any,never blue patches.

I am not looking to get my bore squeaky clean but rather leave enough fouling to maintain good reliable accuracy with as little brushing as I can get away with.

I am tempted to just go with patching in the Broughton but Jason Bs situation with carbon sneaking up on him and causing vertical problems reminds me to keep the brushes handy.I like a little carbon in there for cold first shots but I feel I keep it under control.

 

[AckleymanII]

Be sure to use rubber gloves with the Quick Silver, it causes cancer.

 

[chino1969]

keithcandler,
Thanx for the tip on Quicksilver. I guess the proper thing to do is obtain the MSDS,Material System Data Sheet) for all solvents and chemicals routinely used.
Chino69

 

[Freestate101]

Gunamonth, what is the trade name for the diamond paste and where do you get it?
Thanks,
Jim B.