Is this rust in the bore?

[halvey]

I was checking over a friends 20 ga side by side he offered me for sale this weekend and noticed some “brownish streaks†inside the barrel. It is in the last inch of the chamber, and then starts again about 4†up from the end of the chamber. Otherwise the bores look great.

I ran Hoppes #9 through it with a brass brush then used cotton patches to swab the Hoppes out. Checking the barrel right after I did this, the “streaks†looked to be gone. But an hour or so later – I assume when all the Hoppes evaporated, the streaks were back.

So I repeated the above with a 12 ga brass brush and #9 again. Again, the bores looked clean, but later, the streaks were still there.

I then used CR10 and worked patches through the bores as stated on the back of the bottle. Looked to be clean, but the next morning the streaks were there.

I tried one or the other cleaning procedures 6 times, but still the streaks are there.

Is this rust I’m trying to remove? Is there something a gunsmith can do to clean this up – or should I just skip this one?

 

[dfariswheel]

Could be really stubborn fouling, or light rust.

Whichever, the "fix" is to polish out the barrel.
Your gunsmith can do it for you, or you can do it yourself.

To do a good job, wrap some 0000 steel wool around a used bore brush.
Chuck the cleaning rod in a electric drill, and run the drill at medium speed as you slowly move the steel wool-covered brush up and down the barrel.

It usually doesn't take too much to both clean out any deposits, and polish the bore to a high shine.

 

[halvey]

Thanks for the tip.

If it's really rust and you use this procedure - is there then a better chance it'll come back since it was already rusted?

 

[EghtySx]

If it's really rust and you use this procedure - is there then a better chance it'll come back since it was already rusted?

Well, yes. But if you keep it cleaned and oiled it shouldn't.
I'd be hesitant to call it rust though being in streaks. Rust is usually in spots.

If it's a good deal on the gun you would probably be fine cleaning it out and keeping it clean and oiled even if it is rust since there are no riflings to ruin.