Author Topic: What's this black stuff? (Read 722 times)

Tycer · « **on:** August 26, 2005, 10:47:42 AM »

I have finally gotten the chance to shoot a number of rounds of my new Mountain Molds .360 FP PB 205gr. I'm shooting them in a Win 94 Trapper over Lil'Gun, LBT Blue lube, Dan Wesson 360 Starline brass. 1500-2050fps. WW+2% tin ,water quenched. .330" bearing length.

They leave a black residue on the lands. Takes a few passes with a brush and patch OR a couple of gas checked bullets to clear. Kinda tough. Does not look or act like lead. Does not affect accuracy or pressures. No lube star on the muzzle, LOTs of lube though.

Any ideas as to what it is, or if I should care?

zrifleman · « **Reply #1 on:** August 30, 2005, 07:40:18 PM »

Gas blowby. partially burned powder because the bullets are undersized and too hard to upset into the rifling???

Tycer · « **Reply #2 on:** August 31, 2005, 01:40:17 PM »

I will check upset by shooting into a sawdust box. Good idea.

They are WW, 2% tin, and water quenched, so fairly hard.

I've cast my throat, and am running .001, .002, .003, and .004 oversize. .004 shoots 6" higher and 1" left and loses accuracy. The others shoot similarly, with the .001 having lower fps.

475/480 · « **Reply #3 on:** September 02, 2005, 07:34:06 AM »

Not to be too hard on You,but why NO gas check???Sure seems like you are asking for trouble at that velocity.

Sean

Tycer · « **Reply #4 on:** September 03, 2005, 11:21:01 AM »

It started as a quest for a PB bullet mould for a "bug-out" kit suitable for primitive conditions.

It got to this point via a few leftover 200grain PB Saeco Spitzers I shot just to see if it keyholed in the short barrel.

As it stands right now with Lil'Gun, I can not drive it fast enough to lead. Velocity begins to drop after 19 grains. A full run of different diameters over Herc 2400 is next. Not sure what powder to run after that.

The black stuff has turned out to be lube. If I clean it out, the first 3 shots will not group. I've been told by several people more knowledgeable than I am to not clean it.