What did I do wrong ?

Hey !

I’m starting reloading 300blk subs.

These ones don’t chamber correctly ! They go perfectly in the little ring to verify sizes (Can’t remember the name…)

But in the gun that doesn’t work !

I tried to make shorter ammo, I had the same problem with 556, I started with the standard size 2.25” then I went something like 2.18” (The right one) but the BCG can’t fully close…

Bullet is sized to .309

Cases are resized and trimmed.

Any idea ?

I can reload hand guard all day long but the rifle world is new to me.

Thanks 🙏