I use reloads for my M44.
I've been experimenting with various powders
The bore of my M44 was by far the worst. It was full of orange/brown oil...that left small pitts

I HAD a mint non-issue polish M44....not so much now, funny thing is that there was 0 rust on the exterior surfaces of any of the rifles.
The 22's were all pretty good, The M70 was spotless (thank god, and silicone spray)
The flint lock had a very small amount around the flash hole and a small amount in the bore
The 870 has spots inside but cleaned out with some oiled 0000 steel wool
The M44 was by far the worst....and yet it was the last to be shot, cleaned and stored.
Not sure what to do about the bore on her...I have reservations about the use of steel wool on a rifle barrel and the bronze brush has not improved the bore much.....
A friend of mine put me onto engine fogging oil. It apparently works great for long term storage...but is a pain to clean up.
I've sopped the bores with ATF (Red part of Eds Red) for now but have yet to decide on what to use for long term.
Another friend has suggested melting vasaline and pouring the barrels full for long term storage, yet another has suggested a swab of alox (alox is a corrosion inhibitor by design not a bullet lube)
All I know is that I don't want to EVER find rust on or in a gun again.