Primers can make a difference as far as POI. I don't have a problem with the breech closing on my Triumph no matter which primer I use but I get a different POI . I switched to Win209 and my group was vertical . A perfect straight line about 5 shots in a 5 inch line. I switched back to federal and the group became a tight perfect group. Using T7 primers the group opened up more ,so with the triumph I have to use Federal. My Omega shoots Federal,T7,Remington or Winchester all fine. My Genesis prefers Federal also. It seems each gun is pretty independent and different. It sure gives me an excuse to shoot a lot