.223/5.56 cases to fireform to .223 AI?

[Black Greyhound]

I have Lake City 5.56 Winchester or Norma (primed) .223. Any thoughts on which may work better for fireforming to fit a .223 AI, bolt action PRS trainer?

 

[DarinC]

Either will be fine. If you’re after low sd’s just pick one and run with it. If you’re going full trainer style, do both and just send it!

 

[D̷e̷v̷i̷l̷D̷o̷c̷A̷Z̷]

The one you have more of

 

[Aftermath]

Either will work just fine. I have never found any brass that didn't form well.

I prefer to just load them up full power and shoot them.