Lead ring

[Rockydog]

I was shooting my 6mm TCU Contender for the first time with my own cast bullets yesterday. These were 90+ grain Loverin style GC from a 245497. After shooting about 14 of these I extracted a case that had a perfect ring of lead perched on the case mouth all the way around. It was about the same thickness as the case walls and about that high too. Very little leading in the barrel. I checked after finding this. Never happened again with another 12 or so fired afterward. I was firing Trail Boss in loads varying from 7 to 10 grains. This would have been after loads in the 8 grain range. No leading at all until I got to 10 grains. After 10 rounds at 10 grains there was a bit out near the muzzle. Wondering what caused the ring on the case? RD

[Shiloh]

Could this have been lead shaved from the boolit during the seating process??

Shiloh

[runfiverun]

cases are shorter than the neck area of the chamber.
one of the things i have found to help accuracy is to keep necks as long as possible.
we go through all the trouble of flairing,measuring ,slugging,fitting,fireforming,
whittling brass, annealing,cutting primer pockets,and flash holes.
then cut the case too short by 10 thousandths of an inch and everything else is within a micron.

[Rockydog]

Ahh, the famed Contender headspace issue rises again. When I size cases for this gun I have to back the sizing die out one full turn. Evidently that leaves enough gap at the chamber/case mouth juncture to scrape a bit of lead off of bullets. I suspected as much. Thanks for the confirmation. Now I wonder it it was from one bullet or if itwas from a bunch of them all swaged together by pressure? RD

[chboats]

One thing that can be done is to fit not only the sholder to your chamber but when forming your brass trim the neck to the length of your chamber. I have no experience with the TCU cartridges but I have heard of custom forming 308 brass from 30-06 brass and triming the necks to the length of the chamber. Sometimes this may be .020 to .030 longer the nromal trim to length. To get an idea of how long the chambeer neck is make a throat slug the way LBT recommends and you will be able to see how long the chamber neck is.

Carl

[Rockydog]

Carl, Thanks for the thoughts. I'm sizing these from once fired .223 cases and not trimming at all. My only option to eliminate completely might be to try .222 Magnum cases. But that's a bit expensive. Rockydog

[runfiverun]

it'd only take one soft one that was waterdropped from a not quite as hot as the others mold drop.
it could'v tried to rivet as it come out, or a bit higher pressure spike from a slightly thicker neck.
or thin spot in the brass necks. or just a slight ridge on the throat. or you just missed the champher on one case.....
their throats and such is the exact reason i don't have 30 bbls and one contender frame.

[Rockydog]

runfiverun, The rimmed cases seem to have far fewer issues in the Contenders. They can a PIA but this cartridge is so much fun to shoot, jacketed or cast, that I put up with the aggravations. RD