very nice! love the idea of using shotty shells 
I've not got my M14 in front of me to look, but is there a way to get a rod or something around the gearbox so you can open the bolt and push the shell/mag out?
Maybe even hook it up to the bolt so it ejects as you open it.
wonder if theres a way of using shells on Dboys K98/bar10 conversion? 
was thinkin along them lines as well 
I have a load of them shells I use on my M3 shorty, I havent cut the stock yet on my K98 so Im toying with this idea, the M3 shorty has a small release catch and a door drops down to drop the shell out, the other plus side is theres 30 bb's per shell and they will easily fit in K98 pouches
The thread was hand-cut on a turning machine because it wasn't a standerd european size... probably some american standard
The thread size on the end of the M1 barrel is 9/16" x 32 turns/inch.
I got a die on ebay:
http://cgi.ebay.co.uk/RDGTOOLS-9-16-x-3 ... 5190ee91f5
