I bought the 25 acp conversion a couple months ago for my omega, I've fired off about 100 shots with the conversion so far with out any missfires. I'm using the CCI 400 primers with 100grs of APP 3f, I've also shot the 2f as well with no problems. I hope I never experience a misfire with this setup as it works well in my omega. Honestly my groups did seem to tighten up quite a bit but it could be a combination of different things not just the conversion. The 25's seem cleaner to me and are easier to install and remove from my rifle,
I have not shot this set up in below zero weather yet but I have shot itona couple of 20 degree days with no setbacks.