In talking with a buddy about suppressed rifles and sub sonic rounds like the whispers and blackouts I had a thought would it be possible to take say a savage action and custom chamber it to 7.62x39 necked to 308 but have it throated for longer bullets? The soviet case firing 200+gr Amax or other target bullet should be or close to subsonic if I'm correct in thinking. This would be cheap minus the custom barrel but an easy and simple way to get a 30cal quiet target rifle for playing with. Just neck size the 39 case to 308 and go I believe. Any thoughts or am I just way off the mark?