Need Cleaning Help

I've had this Savage Enfield No. 4 Mk 1* for several years now but have only shot it on a few occasions using PPU FMJ ammunition. Looking down the bore with the MK 1 eyeball everything looks good. I bought a borescope last week and ran it down a few of my rifles to test it out and what I saw from this rifle was totally unexpected. It appears to be heavily leaded, probably from somebody shooting cast bullets at too high a velocity.

I have tried copper Chore Boy wrapped around a copper cleaning brush, JB non-embedding bore cleaning compound and Iosso bore cleaner all followed by several patches soaked with Hoppe's. I haven't even made a dent in the fouling.

Maybe it's not leading after all. What do you think and suggest?

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Thanks

Stuart

Best guess from the pics without having it in my hands...results of corrosive ammo.

Ramped up war time production

My best guess is pitting from corrosive ammo as well. Not uncommon if shooting surplus. If it looks fine with the naked eye I probably wouldn't sweat it too much.

It does look more like corrosion than fouling/build up. If it shoots fine then don't let it bother you.

They make fire lapping kits that might help knock down some of the rust.

put a cork in the barrel (or seal it somehow). Soak it overnight with Hoppes, clean the next day and see what comes out. Next step if that doesn't work- make yourself a home-made "Foul-out"...a welding rod, some small 0-rings and a couple of alligator clips and a little bit of wire will turn a D battery into a device that charges the barrel one way and the rod another. It works with straight ammonia in the barrel...there are plans for "home-made Foul-outs" on the Internet. It works great for getting out really bad metal fouling. Back in the day when you could get surplus Mosins and Turkish Mausers by the dozen from SOG and similar places on the cheap, we used these to uncover some very nice bores.