Picked up my new browning A bolt M 1000, 300 WM,scoped it and headed out to the farm. Found out when I got there only 1 out of 10 cartridges would fit in the chamber, had some fun and came home. I went straight to my bench and started measureing things. Found out the chamber is .513 like it is supposed to be, (just in front of the belt) because any case that measured .5136 wouldn't fit. Anyone know which of the companys makes their brass the right size because Rem &Win sure doesn't . Some cases were up to .516. I think I'll send the gun back for a little chamber polishing but I don't want to 'loosen' it up to much. Thanks for any help/ideas.