Gunscrubber is OK, I have a jar of it, but don't use it much any more as there are better things out there now.

The best ones I've used were Outers Foaming Bore Cleaner, and Hoppes Elite (which I understand is the same as MPro-7)

Also have tried:
Breakfree CLP- I use this stuff when I'm feeling lazy- run a few patches witht he stuff through the bore, then a damp patch through and store the rifle for a couple of days or weeks and reclean.
Hoppes No. 9- It says on the bottle 'Nitro Solvent' and it seems that this is about about all that it will disolve, though I removed some leading from a shotgun barrel once with it, I like the smell, but don't use it much anymore.
Butch's Bore Shine- good stuff works fairly aggressively on copper fouling, stinky.
Kano Kroil- I use it the same way as CLP, weth the bore, let it sit for a period of time- it slowly works its way under the fouling but its stinky.