Got a pair of calipers? Measure out the backs that fit and the ones that don't.
So, I've just noticed something weird. It appears that my old and fairly battered DM7 doesn't take all cocker threaded barrels - only older Dye backs (not new ones) and the occasional Deadlywind back. Try to screw a Eigenbarrel, PE, or any other cocker threaded barrel in there, it gets stuck after a turn and a half, if that.
It's not a problem as such (just means I'm gonna have to run .692 everywhere), but rather an interesting conundrum. Any clues as to why this might happen?
Got a pair of calipers? Measure out the backs that fit and the ones that don't.
This happens with v1 minis sometimes also. In that case it tends to be not accepting the shank od
It's because there was never a standard made or released for Autococker barrels. People have made some abominations of them over the years.
It's why we went and measured everything we could and then created a set of dimensions that should work in all cases and called it "Standard threads". The dimensions for that are here somewhere.
We've only made the problem worse by pretending cocker is a good thread!
They suck in their old form and are tolerable in our modern version, but like it or not they have become a standard in the industry.
Call me weird, but I love the Automag twist-lock style of doing things. There's no rationality behind that, I just think it's kinda neat.
Calipers say that there's a small taper to the breech, tapers from .870 to .860, over a length of 1.125ish inches.
(Here's where my pub quiz knowledge comes in very vague use. It's probably wrong too)
I'm pretty sure that the current qwerty design of keyboards came about after bits of typewriter started to get stuck together, and this method was designed to slow down typing speeds.