HPA vs. tuned CO2

On my .177 850 on CO2 I have replaced all the seals, done the valve mod (both the front and back of the valve) did the port and breech mod and opened up my long paintball adapter one size. I have also installed the Dominator spring, guide and hammer. It shoots pretty good on a hot day out to 40 yards, probably slightly larger than quarter sized groups on cheap pellets (need to order quality pellets, nobody locally has them) I got the Gamo 4 pack of Hunters, Match, and two different pointed pellets at sports authority, but they are obviously the blems. They all have "wings" (left over casting material) . 50 yards tuns doesn't really seem to be practical at least on CO2, or at least with the pellets I have. The groups spread out to a few inches diameter with flyers almost off the page. Will HPA tighten up the groups, or just make it hit harder?