How exactly was it used?
Lachmiller made presses, dies, priming tools, ( a really neat berdan decapping tool, currently being made by someone. The name escapes me at the moment.) They made shotshell presses also. They started in business in CA just before WW2. Sold out to RCBS in the early 70’s This tool was available with different minimum length gauge posts. This one 2.015" . The upper plate was at min when seated down against the shoulder of the upright. A fired or resized case was inserted if it was too long it would then be trimmed to correct or desired length. It was handy for checking a lot of cases quickly. Good vernier calipers were expensive but would do the same job. There is a min-max ground surface on the underside of the upper piece.
RCBS, after taking over Lachmiller, made (and still makes) the Berdan Decapping tool.
Its only failing is that correct setting of the chisel is necessary to prevent (a) breaking the chisel-point, (b) damaging the pocket anvil.
I have one of the depriming tools (original from Lachmiller) and I reshaped the ‘chisel’ some time back for that very reason. It is a whole bunch easier and far less messy than the hydraulic method.
So THAT’s what I picked up at a dealer’s bargain tail years ago! I’ve carried that thing around to dozens of gun shows to sell it. I wonder if I still have it…
There are videos on YT that show how to use it. The chisel/pick might need modifying for different cases. Or it will damage the berdan anvil