"The copper fouling lie"?

[Shadow9mm]

Found this video a few days back. He seems to be making the assertion that having copper in your bore is desirable. That it creates a smoother surface to travel on, and protects the barrel from corrosion, among other things. To me his reasoning seems somewhat anecdotal and circular. My understanding is that there are layers of carbon and copper, kind of like a lasagna, that build up. And his assertion that he has shot better groups at the end of a 60rnd session could just be due to him warming up as a shooter.

Lots to unpack here.

https://youtu.be/rAQaxIlQukU

 

[ernie8]

After 20 years of running matches at my range , one of the major causes of " my rifle is now shooting bad " was copper fouling . We kept copper remover there to cure that , and it always did .

 

[44 AMP]

Conventional wisdom is that copper fouling is smooth, lead fouling is lumpy.

Copper build up CAN smooth a rough bore. This can improve groups. AFTER THAT, or when the bore doesn't need smoothing, copper fouling degrades groups. That's when, and why, we remove it.

 

[Shadow9mm]

Conventional wisdom is that copper fouling is smooth, lead fouling is lumpy.

Copper build up CAN smooth a rough bore. This can improve groups. AFTER THAT, or when the bore doesn't need smoothing, copper fouling degrades groups. That's when, and why, we remove it.

He made a comparison to spackling a screw hole in drywall. that copper would fill the rough patches but once they were full the bullet would just slide over. I always understand it kept building in small layers. Something about the way the metal reacted with a similar metal.

 

[44 AMP]

If you think about it, the copper is being pressed against the bore under considerable pressure. Some of it is very likely to "rub off".

As it builds up, it takes up space, reducing the space in the bore. Bullets still squeeze down but the grip of the rifling gets reduced. When this reaches a certain point, accuracy degrades.