"As head space is going to be defined when the bolt is engage and closed, you pull the striker out of the bolt and that gets rid of the cam action (which is very powerful)"
The engagement faces on the bolt lugs and in the breech ring shoulders are cut as a helix; essentially a segment of an interrupted square thread. It is these surfaces that set headspace, not the striker, .
Your basic Lee Enfield has the same feature, but located on a different part of the bolt and receiver body. In the case of the Lee Enfield, the "twist rate" of the "thread" is one / .10 inch.
If you look at the multi-lug lockup on a Remington 742 / 760 etc, you will see a similar thing. Then there are the larger editions: artillery and naval guns (rifles, as the salty dogs call them), that use separate charge bags. The only way to get a tight gas seal is to screw the breech lock onto the back of the barrel. Sliding breeches work wonderfully with cased charges and rounds because the (brass) case expands in firing and that provides the required obturation. There was even one WW2 Japanese artillery piece that used separate bagged charges AND a rather short brass case to provide the seal. The other handy thing the brass case provides is a housing for the primer and booster. Primers have to be "loaded" separately on pure "bag-charge" guns; a bit like a gigantic capping breech loading rifle. Like this one:
artillery piece that used separate bagged charges AND a rather short brass case to provide the seal. The other handy thing the brass case provides is a housing for the primer and booster. Primers have to be "loaded" separately on pure "bag-charge" guns; a bit like a gigantic capping breech loading rifle. Like this one:
PM
