Copper Buildup???

[o2bwest]

I've been shooting a lot in preparation for a hunt. Of the 2 rifles I have been shooting, a 7mm wsm and a 300 wsm, I have noticed that the 7mm seems to build up substantially more copper than the 300. Why is this? Is it a problem? What can I do about it?

 

[Mike 338]

Probably just the condition of the barrel. Imperfections in the barrel will snag copper, shot after shot. With factory barrels, it's a crap shoot with the condition of a barrel. Shooting and cleaning can sometimes make it better. Having a gunsmith hand lap and re-crown the barrel will also improve it. My experience is that if you've done a barrel break-in (shoot and clean), and it doesn't get better within the first 50 shots, it probably won't get much better.

 

[Varberger757]

I've been shooting a lot in preparation for a hunt. Of the 2 rifles I have been shooting, a 7mm wsm and a 300 wsm, I have noticed that the 7mm seems to build up substantially more copper than the 300. Why is this? Is it a problem? What can I do about it?

The increased copper fouling in your 7 WSM might have different kind of reasons.


- - The kind of bullets you use. I've personally made the experience that some bullets give more fouling to a certain barrel than others. Especially interesting in this case are monos made of copper like the Barnes etc. They have a tendency to give more copper fouling than the usual ones. So change the type of bullet and check the results!
- - Lighter bullets with higher speed may give more fouling. Coefficient of friction.
- - Condition of your barrel? New or old? Have you carried out a reasonable break in of your 7 WSM?


A little advice at the end. You should not compare two different rifles with two different calibres due to their characteristics! That's like a comparison of apples and pears. I hope you'll get the problem solved soon.

 

[o2bwest]

I'm shooting Accubonds. It was a used rifle when I got it. I have had it lapped and recrowned and I have around 150 rnds through it. It is shooting pretty well 1/2 moa at 100.