I would go with a coaxial barrel sealing design for a bolt action build that would be actuated by a QD valve, either electric or mechanical.
http://www.spudfiles.com/spud_wiki/index.php?title=Piston_valve
Thats the nice thing about a bolty rig is that you dont have to deal with the feeding issues that you get on a semi auto rig, and its ALL POWER!!
I have a few designs that would very easily be adapted to a single shot in a bolty if you'd be interested... I haven't pursued them since I have been a little (probably a lot) too motivated to get a semi auto system that I like...
EDIT: That is if you wanted to build a custom rig... I think someone makes a gas conversion rig for the APS that would fit in an ASR...
http://www.spudfiles.com/spud_wiki/index.php?title=Piston_valve
Thats the nice thing about a bolty rig is that you dont have to deal with the feeding issues that you get on a semi auto rig, and its ALL POWER!!
I have a few designs that would very easily be adapted to a single shot in a bolty if you'd be interested... I haven't pursued them since I have been a little (probably a lot) too motivated to get a semi auto system that I like...
EDIT: That is if you wanted to build a custom rig... I think someone makes a gas conversion rig for the APS that would fit in an ASR...