What in hell is the gunk in a new rifle bore? I just purchased a BLR take-done in 325 WSM. I started cleaning it, as I always do with a new bore. I started with Butch's Bore Shine, added Kroil, brake cleaner, WD40, brushed it about 50 strokes, interspersed with patching, etc. I finally got the brown gunk out and clean patches. Anyone know what that crap is?

rust

Cosmoline, or something like it.

Some of the stuff that comes from overseas is a whistling bitch to get out; it's in all the toolmarks and doesn't always seem to be particularly soluble in bore solvents.

Kroil is as good as anything; you must be quite persistent - I usually quit when I've gotten almost all of it out. After shooting, no more brown.

Now, when you start breaking that barrel in, we'll be talking about BLUE...

Brice

Since it is a brand new gun, it is probably not rust.

The gun was fired at the factory with proof loads.
Then usually the factory will put something in the bore to prevent rust.

I recently checked several new rifles with a bore scope, and they were very fouled with copper as ther proof loads are "hot".

I recommend you clean you new barrel with J&B Bore Paste, or Remclean.

I usually run spray brake cleaner down the bore. That will take out virtually everything from carbon deposits to cosmoline. Then clean as normal with bore cleaner on patches etc. Came across this approach while shooting IPSC where guns can be fired a thousand times in an afternoon of heavy practice with cast bullets leaving quite a mess.

I've mentioned this in passing before and I want to point out that I have no idea if it works, helps, or hurts, but it SEEMS like it might help with later cleanings.

At any rate, 6 years or so back I was "talking" with this reasonably well known shooter on benchrest.com or something like that and he mentioned that he treated all of his new and some used barrels with this mixture of colloidial graphite sold by some guy he knew. Sounded reasonable so I bought some, simple enough to use, get the new bore clean, then take a dry patch, put a bit of the colloidial graphite mixture on it (careful, REAL BLACK AND REAL "STAINEY") and run it down the bore a time or two. Like I said, I'm not sure it works, but it seems like it makes later cleanings easier. It DEFINITELY will make your first shot high. I have no idea if the guy is still selling the stuff or not but if anyone is interested, I'll try to find his name or something.