Best way to detect bore rust?

[DeathByDoubleDip]

As the title says, I'm wondering if I need to toughen up and just suck up the cost of investing in a bore light. I have a 91/30 that I haven't shot yet (taking it out to blast this winter break), and I was wondering what's the best way to check the bore condition, since I did expose the metal parts to hot water to help remove a lot of the cosmoline. The bolt had some spots of rust, but I removed some of the more egregious parts with Ballistol.

I realize the 91/30 is a C&R gun but I thought I'd put this here as a general centerfire rifle question.

[Merc1138]

[dirtykoala]

just find something somewhat reflective to put behind the barrel and reflect light into while you looking down the muzzle.

my finger nail is what i usually use.

[Jeff L]

Try running a dry cleaning patch through and check it afterward. That should show any rust.

Instead of a bore light, put a small piece of white paper at the breech and shine any light source so it reflects light into the bore.

[swifty]

Try running a dry cleaning patch through and check it afterward. That should show any rust.

Yup.

[robert101]

If you can't tell the bore is rusted, then that is a good thing. Heavy pitting is bad and you would certainly see that type of rusting. I've never had a barrel show rust so this is a new one to me. I always run a lightly oiled patch through the bore at the end of cleaning. Some like to run a dry patch through - not me. A light coat of oil has always been my practice.

[Roots]

A bore light cost $7..

[Merc1138]

A bore light cost $7..

A piece of paper or a patch and a light that you already have costs pennies, does about the same job.

[Beelzy]

Run a patch with a little vinegar on it down the bore, that will pickup anything rusty.

Make sure to clean and oil bore afterward.

[Coyote Brown]

Put muzzle down in a coffee can. Spray chamber heavily with WD-40 , several times a day for several days. Wipe with dry patches , check for rust on the last patch. Got rust , repeat.

[paul0660]

Run a patch. Reddish brown is rust, black is normal after shooting, green is copper, clean is...........impossible.