Bingo . . . I've been mystified by all the claims for Kroil when compared to my results with it, quit using it for anything years ago.
Not arguing, because I've questioned it as well myself, until recently when I salvaged a prized natural sharpening stone I about ruined, doing edge touch-ups on the fly while wood-working. Don't have time to mess with the mess of oil and only need a slight touch up - but too many times without care. I tried everything I have here; Ed's Red, kerosene, mineral spirits, denatured alcohol, "light oil," PB-Blaster, etc. Nothing would lift the grime out of the pores of that stone.
A few weeks ago, I noticed an old can of Kroil wasting away, sitting beside that stone and I figured what the heck, one last try.
I smeared a light layer of Kroil on the stone and rubbed with a Q-tip and the stuff started coming off, like right now - down to bare stone. Maybe it's something other than its ability to penetrate in this case, but it saved the stone AND I decided not to toss the can of Kroil.
Not to promote a new snake-oil or old wives' tale, but the one thing I've used on old, dirty, rusty, neglected rifles is Free-All, from NAPA. I really can't say it's any better on bores than anything else suggested here, but it makes much shorter work of all the parts that I can SEE as I clean. It's been quite a time and labor saver. I can leave it soak overnight with no ill effect as well. Doesn't smell bad and is only $7/11 oz can.
I recently cleaned up a Remington RB in 7mm with it after lots of soaking and elbow grease with all my other stuff, which was working but I think the elbow grease was doing more than any of the solvents. I'm a big fan of Ed's Red and use it on guns, cars, tractors, equipment, etc., but Free-All still seems to save me a lot of effort on old guns.
EDIT: Free-All does nothing for copper, but seems to loosen everything else on old neglected guns well.
They will tell you whether you want to know or not.
