I've been using top of blade level with top of rear sight - the intent being that this is the most consistent sight picture for the purpose of shooting a group. We aren't terribly concerned with where the group actually IS at this point, just so we can get a group that's better than that of a buckshot pattern at the extreme limit of its usefulness. We'll play with burying the blade once we get to the point of reliably hitting a sheet of typing paper.
I had a bit of an epiphany this morning that may influence the next batch of cartridge construction. It occurred to me that headspace in this system is possibly more correctly measured from front-of-chamber interference to the full range of the amount that the needle protrudes from the bolt head, minus the depth from the rear of the cartridge to the priming surface of the percussion cap, RATHER THAN FROM THAT FRONT INTERFERENCE SURFACE TO THE REAR OF THE CARTRIDGE AS WE'VE BEEN DOING. Here's my thinking:
This weapon system starts building up a fair amount of crud from the first round, which will progressively decrease the amount of chamber space available.
The cartridge is constructed in such a way as to center up when pushed by hand until the cartridge runs into either the lands or the front of the chamber, and the compression of the powder is already accounted for in the construction of the round.
Therefore, the cartridge does not necessarily need to be in physical contact with the bolt head - the flat of the percussion cap just needs to be within reach of the needle. I've got to get down to Pop's place and start taking measurements, but this notion should allow the operator easy loading and firing up to the point that fouling sets the stern of the cartridge back to the point it butts against the bolt head when the action is closed. I THINK THE FLAW IN OUR PREVIOUS EFFORTS IS THAT WE ARE STARTING IN THAT CONDITION WITH A CLEAN CHAMBER. In effect, we're starting the battle already at the failure point of the system.
I am wondering if any of our followers have the length spec for a NEW striker spring for this system. I've got diameter, wire thickness, and number of coils at my fingertips, but I have no notion of how much force the thing is SUPPOSED to exert when it's less than 150 years old. I have a collection of various pistol recoil springs, one of which may prove suitable for sacrifice.