Trimming 300BLK

[rdtompki]

I'm buying a 300BLK upper to supplement my 9mm SBRs. I've reloaded >150K rounds of 9mm on my 1050/Mark VII, but nary a rifle round; I've got the discipline. I don't anticipate large volume and I'm retired so a single stage will be fine. Lots of good info on die sets, etc. Since I intend to start with either a)new 300BLK brass when I can get my hands on same or b)reformed 223 brass, assuming I can get several (5-6?) firings out of this brass how often would the brass need to be trimmed? That's the one step of the process that doesn't in any sense transfer over from my pistol cartridge experience.

[LittleLebowski]

Your mileage may very, but I never trim .300BO and neither does my best friend.

[rdtompki]

Your mileage may very, but I never trim .300BO and neither does my best friend.

That's what I was hoping to hear. I only need minute of man accuracy out to 200 yards; will be my truck gun in our small RV.

[LittleLebowski]

That's what I was hoping to hear. I only need minute of man accuracy out to 200 yards; will be my truck gun in our small RV.

I'd spot check and still resize, but I just don't see noticeable issues with my .300BO brass and my use case for mine is much the same as yours.

[RevolverRob]

I'm only trimming stuff that is freshly formed from 5.56 and mostly just for uniformity. I haven't seen any significant lengthening of fired brass, I've got some that's now been fired and reloaded 3x and they're maybe a couple of thousandths longer.

[jtcarm]

I just started with .300BO, buying 250 rounds of 1x LC brass.

I found the lengths to be all over the place and trimmed em all to 1.36.

[TOTS]

I, too, have never had any .300 flow enough to need trimming.