[humblegunner]

The Mosin breeds rust in the barrel.

I’ve tried Hoppes, soapy vasser, bore cleaner, Windex.. I’m still cleaning the thing for a week until I give up.

I’ve resigned myself to running a couple patches through it prior to firing.

It’s the ammo that does it...

[altsehastiin]

M-Pro-7. It’s not as aggressive as Hoppes, but it works well if you clean regularly.

[USNBandit]

To go after hard core bore corrosion you may have to go to JB bore cleaner. It has an abrasive. I have only used it to break in barrels by the manufacturer’s instructions or attempts at reconditioning really old barrels. My father thought of it as a last resort, but I don’t think it’s that bad.

[jboot]

Clean within two hours of firing with lots of hot water (it’s OK to use cold water but hot water evaporates faster). After that clean out the gilding metal with a copper solvent (Hoppes is fine) and finish the job with WD-40. Yes, I said WD-40. WD-40 is an EXCELLENT rust preventative but a terrible lubricant and loses effectiveness rapidly with age. Be sure to lubricate only with a quality gun oil, and swab the barrel with fresh WD-40 every six months. You shouldn’t have any more rust trouble,

[wagglebee]

The thing I've found works best with the Mosins is to plug one end with a rubber stopper, fill the barrel with Hoppes, stand it on end in a bucket and leave it overnight.

[Professional Engineer]

I’ve tried Hoppes, soapy vasser, bore cleaner, Windex.. I’m still cleaning the thing for a week until I give up.

I used Butch's Bore Shine and 338 brush to finally get a MN clean.

I'm not sure about Laz's method...