Good evening. I'm starting up loading .35 Remington with a cast bullet, and I'm seeing an new-to-me phenomena:
I observe a fringe of lead plating on the necks of the cases near the mouth after firing. This is consistent from min to max loads of 2400 under the Lee 358-200, cast of COWW, water dropped, HiTek, copper GC'd, sized to 0.360. The cases are reformed from .308 (yes, the case heads are resized to .35 Rem spec), and neck turned to 0.014" (just thin enough to clear the chamber neck with the .360 bullet seated).
The gun is a 2010's Marlin 336 in .35 Remington, microgroove. I'm printing 2" groups at 50 yards, probably mostly due to my lack of practice with an aperture sight. Even after 30+ rounds in a sitting, there is no leading whatsoever; it's one of the cleanest cast loads I've ever seen in a medium bore rifle.
Is this normal?