[5R milspec]

for the most part it does not matter to what length you trim the brass as long as it does not come in contact with the chamber.but for him it must matter for he has made a tool.

the longer you can hold your brass to a chambers length the better it will be for the rifel.it helps out in the long run of things by saving the throat of the rifel.premature throat erosion will cause less accuracy in a shorter time for the life of the barrel.it really shows when we load our rounds to max and keep them their.or when we load really big bullets.so by cutting the brass to fit the chamber helps prolong the life of the chamber.how much better does it help I cannot say for I have never tested for it.better yet I have never shot out a barrel.most shooter or say me like to keep our load in the middle to save our throats.

again for the most part it really doesn't matter.most just cut their brass to the spec given to the chosen case of choice.one thing does come to mind though.I shoot a 308 and with my loads it should be able to get 5000 or so rounds with no trouble.I even cut the brass short and not to the chamber.( spec )for me I'm not worried about it.when or if accuracy falls I'll just have a smith cut it back and rechamber it.