You can still use it, different brand bullets and even different weights of the same brand will have different C.O.L. and not all of them will use the magazine length as the C.O.L. I just loaded up some 110gr Hornady SP at 3600 fps for my 300 WSM and the C.O.L wasshorter than the magazine length. If you ever get a single shot you will not have a magazine length to limit the C.O.L. My Ruger #1 in 7x57 mauser has a very long C.O.L. of 3.147" with a 150gr BST. it looks funny but it increases the case capacity.