Shoulder setback or headspace reduction is an issue with reduced pressure loads whether the cases are new or have been fired. I shoot many 30-06 reduced loads and it is an issue. Protruding primers are the first giveaway. Trailboss won’t make enough pressure in an ‘06 case to keep it from happening. I have no experience with the .223 case so can’t offer any input there. Thinking out loud and speculating I would guess the Ackley cases would be less prone to this because of the steeper shoulder. Reduced loads are a hoot! My favorite reduced load in the .223 is with about 16.5 grains of IMR4227 and a 55 grain bullet of your choice. Gives around 2,700fps.
INGWE,
You are on to something that is a lot of fun.
Good luck and take care,
Rick
