I got 120x rounds of Remington .223 55 gr. JHP, and 260 rounds of Remington .223 55 gr. FMJ today... There is a noticable different in height between these two rounds. I know .223 headspaces off of the neck -- but I also know there is a min/max length for a loaded .223 round. Can someone check their load book and tell me what it is... I'm curious to double-check these.