Odd fouling

[jonk]

I scrubbed my Yugo M48A down to bare metal last weekend, including Eds Red, JB bore paste, and 2 different sorts of copper remover. CLEAN! This weekend commenced to try some cast bullets. 170gr FNGC from a group buy, quenched WW, lubed with 50/50, sized to .325, over IMR 4895- 5 each of 25, 26, 27, 28, 29, 30, and 31 grains, as well as 5 with 17 gr of SR 4759. For the 4895 loads I was using 2 grains (roughly) of polyester pillow filler- the famous dacron wadding I'm just getting into.

All loads shot pretty well with the best being around 28 grains- but none were bad and I got no signs of leading. All were seated just off the lands.

So I clean the bore- a few passes with a bronze brush and then Ed's Red. The main powder fouling came out quickly, the black stuff. Then though something odd; a brown fouling, slightly darker than rust, that wouldn't totally clean out. I'm at a loss. It isn't the color of your typical lead foulding (the gray streaks), it isn't rust as the bore was shiny and I ran a dry patch through before shooting and IT was clean. The pillow stuffing wasn't melted- I examined some of the tufts on the ground. I can't see a lube failure or there would have been leading, and there was a nice lube star on the muzzle showing I wasn't running out.

All I can think of was that the lube was somehow getting in pores in the metal- which would be ok- or that the pillow filling was somehow still leaving residue.

What do you think?

[Bass Ackward]

Then though something odd; a brown fouling, slightly darker than rust, that wouldn't totally clean out. I'm at a loss. What do you think?

If you are sure it ain't rust, it .... probably isn't.

I think that you were shooting a lube with heavy petroleum products in it. Combining that with powder carbon produces a tar substance. Coming out "endlessly" slow like it is, it will have a darker brown appearance. The slower the powder (more carbon) the heavier and longer it can be to clean out.

But lead is also a polisher. After an aggressive cleaning, particularly with a heavily fouled piece, lead is bound to loosen up some more stuff. See if it happens next time. I use a patch with car polish (designed to remove tar) and patch it in, let it soak and then patch it out. If it has Carnauba in it, that will leave a nice bore coating for the next secession.

[runfiverun]

i think bass has hit it,you could have also have had some cosmoline residue in there.
i have had that stuff seep out of god knows where on hot days when shooting.
and this was way after you would think there was still any left.

[jonk]

If you are sure it ain't rust, it .... probably isn't.

I think that you were shooting a lube with heavy petroleum products in it. Combining that with powder carbon produces a tar substance. Coming out "endlessly" slow like it is, it will have a darker brown appearance. The slower the powder (more carbon) the heavier and longer it can be to clean out.

But lead is also a polisher. After an aggressive cleaning, particularly with a heavily fouled piece, lead is bound to loosen up some more stuff. See if it happens next time. I use a patch with car polish (designed to remove tar) and patch it in, let it soak and then patch it out. If it has Carnauba in it, that will leave a nice bore coating for the next secession.

You may have something. While I filled the hopper with 50/50, there was probably some old lube left in the die- and the last batch I made I put vaseline in as an experiment. The vaseline leftovers may have caused the issue.