stagpanther
New member
Since I have thousands of spare 5.56 cases I've been amassing for many years my latest AR builds have been variants of necking up or down the basic 5.56 x 45 case--but the 300 BO is my first go at a case OAL cut and neck-up. My first few goes at simply cutting and trimming with home gear kinda sorta worked--but wasn't especially consistent or squared--so I bit the bullet, so to speak, and bought a Litlle Crow trimmer.
For some reason I was dumb enough to think that people actually simply trimming down full-length 5.56 x 45 cases but quickly figured that wouldn't work. Similarly, the cutter (at least mine) won't do any trimming until the trim diameter is the actual neck diameter for the 300 BO.
My solution is pretty simple--start with the 5.56 case and using the cheap Ryobi bench belt sander and grinder combo I simply grind down the case to the base of the shoulder, resize in the 300 die (with decapper removed of course) and then use the Little Crow trimmer to do final case trim. Worked well for me.
These are left-over LC and FC cases which have all been pocket swaged though most of them didn't seem to need it. nosler 125 accubonds driven by W296 between 16 and 17.5 grs.
For some reason I was dumb enough to think that people actually simply trimming down full-length 5.56 x 45 cases but quickly figured that wouldn't work. Similarly, the cutter (at least mine) won't do any trimming until the trim diameter is the actual neck diameter for the 300 BO.
My solution is pretty simple--start with the 5.56 case and using the cheap Ryobi bench belt sander and grinder combo I simply grind down the case to the base of the shoulder, resize in the 300 die (with decapper removed of course) and then use the Little Crow trimmer to do final case trim. Worked well for me.
These are left-over LC and FC cases which have all been pocket swaged though most of them didn't seem to need it. nosler 125 accubonds driven by W296 between 16 and 17.5 grs.
