case trimming

[6.5x55swm]

what do trim your brass to? In my speer manual#12 it says to trim my 22-250 to 1.920 in the #11 manual it says to trim at 1.902. If i trim at 1.920, it works very good in my rifle, just wondering

 

[J Stuart]

You may want to measure the chamber neck length before you decide on a trim length, as they are generally on the generous side.

 

[6.5x55swm]

how do i measure the chamber neck length?