Most of my rifles have had more copper fouling with these bullets than most others. I do clean properly. I have seen measurable accuracy degradation after as few as 20 rounds. It is still acceptable hunting accuracy but not pleasing. I find this to be most noticeable in the smaller caliber rifles.

I do use these bullets (and several others) for hunts in North America where just a few shots are the norm. On longer duration hunts in African countries where proper cleaning is difficult or impossible I am giving up on them in my light rifle that will be shot the most. I do like them in 375's and larger.

In my Blaser R93 .375 H&H I shoot Barnes TSX 270 and 300 gn. They do impart copper fouling quite readily but can't say I notice much accuracy loss. I shoot only to 200 yds max. In my Blaser 30.06 barrel I shoot TTSX 165 and 180 gn and I think they foul slightly less. Overall my Blaser barrels seem to copper foul easily with most bullets.
I have Tikka rifles in 30.06 and .300 Win Mag in which I shoot TTSX 150 gn and 165 gn. Their stainless steel barrels foul a lot less than the Blaser barrels, and foul about the same with any other bullet. With these rifles I routinely shoot up to 50 rounds with no noticeable affect on accuracy even when fouling is obvious at the muzzle. Comparatively, cleaning out the fouling is quite a bit faster, and easier, with the Tikka rifles.

Isn't copper fouling with these or any bullet for that matter directly proportional
to the surface finish of the bore and quality of the steel used? I don't see it as
much in a finely honed barrel.

I also do see less fouling in premium barrels. It is most noticeable in my original factory barrels such as my Model 70 rifles.

Although it is not as bad in my premium aftermarket barrels, it is my experience that the soft copper does foul more quickly.

To most fellows the copper build up seems not to be an important issue. A bit of time and effort with a cleaning rod and proper solvents makes things right.

In the one rifle that seemed to foul with TSX's I ran a few Tubbs Final Finish bullets through it. They smoothed out the rough spots and it hasn't been a problem since. It is Mrs Blacktailer's 308 Kimber and serves her and I for our light rifle on safari. I usually clean it after 50 rounds or so and haven't noticed any accuracy problems.

In Europe you get "improved" barnes bullets which are covered with nickel. I use them but to be honest I have never really checked if it makes a difference or not....

Seamaster, I agree with the posters, who suggested, that a rough bore is the likely problem. I've a match grade Douglas on my .375 AI, and can easily go 100+ rounds without cleaning. Had a friend who had one of the earliest Rem. stainless. Very rough bore, terrible fouling, and groups at 100 yrds. resembled 00 buckshot shot at 25 yrds. He polished the bore and reduced fouling, while getting the group's down under 2" . Still pretty bad, but a vast improvement. Since the early days of Barnes X bullets ( my only hunting bullet) , I polish the bore of every rifle I work with, whether needed or not!! memtb

As a benchrest shooter I do have a vague understanding of how barrels generally work. Each barrel is different from all others. Smooth barrels foul less than rougher barrels. Most original factory barrels are not as smooth as custom barrels or barrels that have either been lapped or have become worn.

My initial comment was intended simply to indicate that I believe that the copper pills seem to foul more than most others - all other things being equal.

They do foul a barrel more than most bullets, a lot of that depends on the barrel, and the bigge the bore the more copper gets displaced in the bore, nature of the beast..

But with the Wipe Out a couple of passes and its good to shoot, so its not a world shaking problem. As to hunting it will not destroy accuracy, it just opens up your group a bit, not enough to ruin a hunt I wouldn't think..Never in history has an animal been killed with a clean bore, not one...

The amount of fouling is highly variable. I know of one BSA that would copper foul so badly that after two shots t started being a 3-4 minute gun.

I cured that rifle with Dyna Bore Coat and very highly recommend it for anyone shooting any monos. All my rifles now have it installed. I have yet to see any issue after installing DBC in any rifle.