For cleaning ARs, I have found the Hoppe's .270 - .308 patches more effective than the "correct" smaller ones for .223.  Passing one or two of the larger ones through the bore gets out more of the fouling more quickly than several of the smaller ones, though with added friction.  Also, when the rifle hasn't been shot too much, a wire brush seems unnecessary to get a clean, shiny bore.  But do the larger patches and resulting added friction hurt the bore, even if only in the long term?

I can’t imagine that tight patches could ever approach the friction caused by a .223 bullet.

Keep in mind, though, that a really tight patch can cause your cleaning rod to bow and rub against the bore with some force (assuming you’re pushing the rod, not pulling it).

I wouldn’t see this as much of an issue with a one piece, coated rod.  I think it might be more of a problem with a segmented steel (or, heaven forbid, aluminum) rod.

Note that patches vary quite a bit from one manufacturer to another.  I can’t imagine that you’d ever be able to get a thick mil-spec .308 patch down a .223 barrel.

The exact size and type of your jag/loop can also affect the fit of the patch.

Also keep in mind that, while the bore may appear clean and shiny, you really do need to occasionally use a bronze bristle brush to clean carbon out of the edges of the rifling.

I have some GI here that are 1 3/8" square and some pro-shot that are 1 1/8" square.

I use the 1 1/8" patches in the .223 with the Dewey Rod and wrap type jag mostly.

My .308 Patches measure 1 3/4" square.

HTH

Danny

Thanks for the advice.  I've been using a US M16 cleaning kit with the segmented rod, which seems stiff enough not to to bend under the circumstances (hopefully).

What if you tightly tied some fishing wire (edit: plastic not metal) or nylon string around the middle of the patch then use a plastic coated wire to feed the string til you could pull it? Then you wouldn't have to worry about rubbing against the bore? Only thing is you would have to cut it each time to put on a new patch.

That is the hot setup IMO. Way better than a regular jag and infinitely better than a loop.
Mark