I just use a bore guide and a mop on the end of a rod. Soak mop with BoreTech Carbon Remover thru the solvent port of the guide and position it just past the end of the guide to soak the throat area. Let it sit...won't hurt the barrel. Then patch out and look see.
Also, I know Frank Green of Bartlein uses Rem 40X...just about only mild abrasive he will use....on a Parker Hale style jag to work the throat area over. I've used it and it did seem to really clean up the carbon in that area.
Best of luck.