Quote Originally Posted by BoilerUp View Post
I really appreciate that you've shared your experience here so we can all learn from it. I never form my own brass but that's largely because I really don't like the idea of having brass that doesn't match its headstamp. For 300 BLK brass my preferred approach is to shoot factory ammo and save the brass. The S&B loaded ammo can be a pretty good value compared to buying just brass.

For the rounds you already have loaded, should you inspect each round with a case gauge? That should pick up any bulging issues, I would think. I never do that with loaded ammo but in this case it seems like it would tell you if you have any more rounds out of spec.

Also, I wonder if running the formed brass through a Lee Collet neck sizer as one last step would help. If the neck is too thick, I suspect the brass would mushroom and be ruined in the collett die.
Great questions... and yes that was the primary motive. I want others to learn what to watch out for.

As far as forming brass I am not worried a bit about mixing up brass for range ammo. 300 BLK is totally different in shape and size. Now though I am obviously rethinking that. Before the only time I really segregate brass was for match ammo etc. And I am not loading match ammo in 300 BLK :)

Fortunately I just loaded a little bit. I was actually finishing off shooting the remainder of the batch I had when the blow up happened. After 2 or 3 mags I had something like 20 rounds left and I just threw them out. Some of those rounds were damaged so I didn't want to mess with that obviously.

After forming the brass the cases would drop freely into a gauge but once a bullet was inserted the problem manifest itself. I would have to drop test each loaded round to detect it.

I do use a collet crimp die but that doesn't help. At very least if you crank it way down it will deform the bullet a lot before it does anything regarding neck thickness. I am not sure if that's the same die you are talking about but that is already in use.