Strange copper fouling

[Flynt]

I have a 7mm/08 Sako Hunter, and I've never felt good about it. My groups aren't that great, and (don't know whether this is related or not) the bore has always collected a LOT of copper fouling in the grooves. Last night, after cleaning the grooves down to bare metal, one groove still had a noticeable deposit of copper, starting at the muzzle and going back about half an inch, where it faded away. My question is whether that could indicate some irregularity in the bore, maybe a burr on the crown or something else that's not right and is causing that little bit of copper to remain. Thanks.

 

[dfariswheel]

It could indicate an irregularity.

I'd suggest getting a jar of JB Bore Paste from Brownell's.

Use this to clean the bore, and remove the copper fouling.

If it does this again, continue using the JB every time you clean, and it may help remove whatever is causing it.

 

[thales]

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Sounds like a job for fire lapping. Kits and instructions are available from zediker.com and neconos.com as well as from Brownell's.


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[Flynt]

What's fire lapping?

Is that where you use special abrasive bullets? I think I'm going to show it to a gunsmith today and see what he thinks.

Also, last night I discovered another issue that could be affecting my groups. The bolt at the back of the trigger guard assembly that screws into the rear of the receiver had come completely loose! In fact, I thought I had lost it, but luckily it was in the case I used to take the gun to the range. I screwed her in tightly, but I wonder it I should use red loc-tite? If I do that, will anybody ever be able to work on the gun again, or is it permanently welded? Thanks.

 

[USSR]

You do NOT want to loctite your receiver screws. Check them for tightness prior to each shooting session, and YES, them being loose can cause accuracy issues.

Don

 

[Flynt]

That makes sense to me. Thanks.

 

[thales]

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Fire lapping

Yes, it involves firing bullets with a graded series of abrasives embedded into the bullets. The idea is to remove tool marks, constrictions, rough spots, etc., from the bore. At first it might seem like a really horrible thing to do, but it is not likely to remove more than .0005" from the bore. Most custom quality barrels have already been lapped by the maker and will not benefit from fire lapping. Popularly priced factory barrels can be quite variable in quality: some are pretty good, some are pretty bad. The ones that exhibit intractable fouling or inaccuracy are the ones that are likely to benefit.


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[Flynt]

Thales, thanks for the info. Since I don't reload, I may to settle for RB bore paste. I had hoped to avoid these kind of issues by buying a high end Sako, but I guess not. Thanks again.

 

[Ol` Joe]

Get a can of WipeOut. It will remove the copper over night and isn`t abrasive or chemically damaging to your bore. Give the bore a shot and let it sit `til morning, come back dry patch it out and oil, you`re done and no copper! I`ve used this stuff for a couple years now I`ll never go back to other cleaners.

http://www.eabco.com/WipeOut.htm