Copper left after rifle cleaning

[Byte Stryke]

Your over zealous cleaning is more detrimental to accuracy than the copper. Leave the copper, it is a gilding metal which means it leaves a thin coat on the interior of the bore. As long as it is not too heavy this is a good thing as it helps to create a better gas seal.
A good rule of thumb: a quick swab and patch solvent cleaning is fine for average cleaning. Don't scrub the bore, just a wet patch and dry patch and get the chamber clean.
If you start to see your groups degrade then clean your bore with a copper removing solution. Leave the scrub brushes alone.

^Listen to this guy

I have noticed a lot less copper in the bore since using the CFE 223 powder for my range rounds.

A clean bore is also detrimental to accuracy. the first shot- or sometimes two or three shots- the oil or lube/grease/solvent left from your cleaning process tends to play hell with as sealing and projectile speed, resulting in a "cold bore flyer".

I pass one NYLON Brush through with oil after a trip to the range and then cotton only.
the only reason I leave any oil in the barrel at all is because I now live in Georgia and own a Kimber
The damned thing tries to rust while I am cleaning it.

[BPTactical]

Bert, do you think even the once-through bore-snake with a few drops of CLP sometimes followed by a patch that I run after a range trip is too much? Groups are consistently 1/2MOA or better-than-I-am...

Nothing wrong with that plan other than the BoreSnake IMHO.
The damn things hold debris. Debris that drags though your bore everytime you use it.
A better plan would be a one piece stainless or teflon coated rod. The nylon brush Guy noted is ok, just clean the brush after every use.
The other bad thing about a BoreSnake-wait until your using it and the pull cord breaks. A stuck BoreSnake can be a number one mother *@#*er to get out. DO NOT try to pull it backwards, you will just wedge it in tighter....