Originally Posted by
gloob
That's a new one to me, having non-GC/PC cast bullets tumble without leaving any fouling. Just when you think you have things figured out.
"Noticed they had lube in the lube groove. Which is odd as I don't have anything to do that."
You probably do, though. Lots of folks assume lube grooves don't matter when using tumble lube, and that a grooveless bullet would be the same as a grooved one. But if you coat the bullet with lube and then run the bullets through a sizing die, you might see this effect. That the lube gets completely cleaned off the bearing surfaces. But some of it gets picked up by the lube grooves, and the grooves can even get completely filled. I would imagine that the same thing happens when you fire an unsized TL'd bullet.
You can also fill in the small grooves on a TL bullet with lube, if you tumble them in a single layer in a smooth flat pan.