So I have been pumping out OFB LC like a madman.
Got the 1050 set up with the trim head. Dillon decap in 2, swage in 3, trim/size in 6, Lyman M die in 8.
Ran about 3000 rounds with the M die set to where the bullets just sat into the case mouth. I pulled a case every so often and check it in the case gauge, check the pocket, overall length, and set a bullet in the case mouth to gauge the M die expansion of the case mouth.
At one point, gradually I started to feel more resistance on the downstroke, thought maybe I didn't lube enough, or some SAW brass or something.
I stopped and checked everything over, and found that the M die had come loose, and screwed itself down. I flared the brass alittle bit. Prior to this I had not been expanding to the point of "flaring", only expanding the case mouth. I was able to pull that whole bin aside and separate it.
I took the calipers to that brass, and on the outside of the case mouth, it is .252-.253.
I readjusted and found the spot where I could move the M die stem up or down, with no effect on the case mouth expansion, about .247. so I reset it at that setting.
Dug out some of My first brass, and it was reading .247. That seems to be the sweet spot of the die where the bullet set in nicely.
Has Anybody ever checked this measurement? if so, what was Your measurement?
Also, do You think that the Dillon taper crimp die will crimp this back into tolerance?
Half tempted to just toss it into the Blackout bin as it is OFB LC, but I got enough rejects in there as it is.
Thanks, Dave