Have been conducting "experiments" involving copper-fouling for over 30 years now.

Yes, it does make a difference in SOME rifle barrels--could describe some but have already done this in my articles and books. It also can be so minimal (or even non-existent) in SOME barrels that there's no point in cleaning them.

Between those two extremes have seen a .338 Winchester Magnum barrel that built up copper-fouling so quickly that within 15 rounds after cleaning to bare steel, accuracy started to deteriorate from 3-shot groups with some loads in the .6" range, to ALL ammo going over 1.5" after 20 rounds. At that point the bore looked copper-plated at the muzzle even with a bare eye--and also throughout with a bore-scope. The cleaned bore was among the smoothest I've ever seen through the same bore-scope--but it took a LOT of cleaning to get there. I was about to replace the barrel when Dyna Bore-Coat appeared--which reduced the cleaning interval before groups even started to open up to around 75-80 rounds. This was with standard gilding-metal jacketed bullets, NOT copper-jacketed or copper monolithic bullets, which tend to foul more.

The most extreme in the other direction was (and is) a heavy-barreled Remington 700 .223 purchased around 20 years ago. With Ramshot TAC (one of the cleanest-burning powders available--when loaded to 60,00+ PSI) accuracy did NOT deteriorate after shooting 500 rounds--and there was only a faint hint of copper when looking through the bore-scope. I cleaned it at that point--and accuracy deteriorated for the first couple of groups, then went right back to shooting as accurately. It is still doing that, several thousand rounds later--though I did use bore-lapping bulllets to smooth the throat after around 2500 rounds, and installed DBC.

Powder fouling also has an effect. The fouling left by old-style spherical (Ball) powders is very abrasive, so tends to increase copper-fouling. But improved spherical powders like TAC don't foul much at all--and then there are the increasing number of powders that include anti-copper compounds. And they work. Have shot brand-new factory barrels with up to 200 rounds of handloads using powders with anti-copper compounds, with no increase if visible fouling after the first few round--and even then its very fauint.

Have seen similar results, at both ends of the spectrum, from a bunch of other rifles. Have detailed all of this "research" in my Gun Gack books far more extensively, both the effect of copper fouling on accuracy and the effects of both cleaner-burning powders and anti-copper powders.

The guy is FOS. But such BS also often increases you-tube video views--which is how you-tubers get paid.

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