Al,
The partially sized case and the fully sized case look like they have a slightly flared, "bugle" mouth. What do you think is the cause of this?
My theory is that the mouth of the case becomes work hardened when the brass is tumbled after all forming processes have been completed. The "annealing" is not really a true anneal but a "stress relieve" so it does not eliminate the work hardened zone.
Jay, Idaho
That's Good Thinkin' right thar Jay!
I'd say that's quite possibly the problem. I've ordered my latest reamer to be short enough that I can trim just a little BEFORE necking down, then finish it later after fireforming. My thought was actually to run my little 60degree chamfer tool inside and out to ease the start into the die but your clarification will probably result in me being a little more aggressive this first step
I'd read this to mean that the casemouth was collapsing a little from end pressure before slipping into the die, you've given me another (better IMO) reason.
BTW, the only reason that the fully necked one shows slightly less "bugle" is because I'd dragged a lengthened expander mandrel back thru it. I kinda "fixed it" at the expense of changing the crush fit datum. Thanks to you I think now that I can solve both problems at once while maintaining a consistent crush.
Following are some more pics.
The first one again shows the offset, indicated by the flared area where my freshly ground cutter stopped. I grind my neckturners to cut the flare into the shoulder, up the shoulder, and then STOP CUTTING. In this case I sectioned because my "flared cut" at the n/s junction was IMO too deep, my cutter angle is too divergent from the existing angle of the brass.
The closeup shows the resultant step. I've opted to better match the angle with this cutter, it's "OK" but not great.
The last two pix show how the un-trimmed casemouths are all cattywampus, tilted as much as .015 whether fired or unfired. In fact firing makes the tilt worse.
If I subscribed to Turbulence Point Theory I'd be all worried about eccentric swirl patterns
LOL
al