Is there some patterning in the way a badly fouled barrel shoots?

I mean, in which way would you expect its groups to be affected, just by a random separation of the impacts producing now a larger "normal" group, or would you expect some shots clustering in one nice group but throwing uncalled flyers around?


Trank you.

My experience is basically more widely-scattered shots--but in general don't run into many barrels that copper-foul much anymore, even in factory rifles.

My limited knowledge indicates merely larger groups. The faster and to what degree this happens, seems to be determined by the bore condition.

Until a few weeks ago, I hadn’t cleaned my rifle in 2 or 3 years ( yes, I’m lazy), though it doesn’t get shot a great deal. It was still shooting sub 2”, 3 shot groups @300 yards. I haven’t actually done a round count to determine at what point accuracy deteriorates! memtb

I got that kind of lousy grouping with 123gr AMaxes and Swiss Re70 powder in my normally very accurate 6,5x57R Blaser.

I had not cleaned the gun in a looong time and the Hawkeye borescope revealed it was badly fueled with copper and filthy with powder residue too.

I have cleaned it to bare steel and, after you confirmed my thoughts, I will try something different: it will be 135gr ATips with MRP, a powder which gives very good accuracy with Berger 135gr and 140gr and 140gr AMaxes.

Thank you!

Alvaro

I have a 25-06 that has more than 3000 rounds through it. I hadn't cleaned in in the last 3-400 shots and it was showing it - 1.5-2.5" groups. I went down to the metal (verified by borescope) and it took 28 rounds of a known accurate load to get it back to shooting the .75" groups I was used to.

IShammy, if you try something different, you will lose your baseline question regarding the bullets and powder you have used to get lousy groups. I'd clean, and then shoot the 123s and RL load for reference, THEN go try the other things. In fact, I'd do it twice to confirm. It may well be that rifle wants to love what you're shooting now.

It seems my magnums ALL copper foul! I need some of that Montana dust, I think.

John,
I guess your barrell not fouling anymore has to do with the use of DBC... This is the barrel I shoot the least and DBC being impossible to find overseas the little I have I save it as much as possible, which is probably pointless as ti stands better in any barrel than in the shelve. So, I will apply it to this barrel as well and not look back.

Dave,
You are absolutely right. I will shoot the same AMaxes over a clean barrel and see the results and find out whether the bad groups are attributable to a dirty barrel or to load dislike by the gun. Well seen!

Thank You,