Only complete case separation I've ever had was a .223 tracer reload during a evening MG shoot. Got it out jamming a .357 pistol brush pulled inside then pushing from muzzle. But range .223/5.56 pickups are less likely overstretched (which is why they separate) vs 7.62x51/.308 bulk purchased.
Judging from other threads/posts most folks use headspace dies to assess reloaded ammo or sized cases. You can use the chamber of your rifle for that. I use my Wilson headspace dies to assess bulk and/or range-scrounged unresized cases. Not so easy to do with your chamber. Looking for badly overstretched pieces to cull. Do it by feel while occupied with something else. Like a Hallmark movie your wife wants you to watch with her.
It's easy to believe you need a SB sizer if you're not culling badly overstretched brass. But that's begging for a separation.
There are many gizmos that will decrimp primer pockets. Used the Dillon, RCBS, but often all I need is Dad's ancient C-H. Swage, not ream.
The decision to load .223 is personal. No right or wrong answer for everyone. Too many variables.
