I've messed with 2 tikkas T3's. A 270 that was 5/8 or 3/4 but a 270 isn't my style so I passed it on to one of my project managers. (was going to turn it into a 7 x 57 anyway) and the current 338 fed. The 338 is a 1/2 inch gun. It seems to like my "quick cleaning" method at the range, I don't dare do a really good cleaning on it, takes about 40 rounds to get it right.