Been to the range 2 times with my Paramount now. First time only shot 6 or 7 times to get it zeroed at 100, but yesterday I put another 20 through it, roughly 10 40cal 260gr Dead Centers (didnt love them) and 10 more of the 180 ELRs. The blow back issue is really odd. On my rifle it was only every 4 or 5 shots. The dirty ones came out filthy all over. On the others the variflame adapters came out sparkling clean. I haven't measured them yet, but I almost suspect the ones with a lot of blow back may be a hair shorter so they didn't compress the spring as well? I reached out to CVA this morning an they responded within 30 min to let me know they were sending an upgraded bolt head spring that will seal it better. When I asked about the details they said - It is stiffer the one you have can be compressed by pinching it between your fingers and the replacement cannot easily be crushed. Great customer service! On a side note, results were good with the ELR and 105gr (wt) of 209. Three shots touching at 100yd. I'm still a bit recoil shy though so I am working to get used to the trigger and the jump without flinching and pulling the shot. I think the group will shrink a little when I get used to it. Overall this is a really nice sub $1K easily 400+ yard unmodified factory rifle. I think some minor tweaks will have this thing shooting awesome. And I cant wait until we see more results from tests with other custom bullets. I have some 250gr 40cal Pitman AccuMax bullets on the way. Will try them with a Harvester blue crush sabot and a tad lighter charge of 209 and post results in the coming weeks.