Personally, I think it would be like putting lipstick on a pig. You had said that you already invested in a top notch barrel and trigger so messing with the receiver is moot. For the $$ and time that will need to be invested, why not play with the load as that will have better effect on what you are trying to achieve. In the end, the upper is just the toolbox to hold the trigger and the barrel which are the most important parts. No different than in a bolt gun.