I have heard the mantra concerning high port pressure and the M1 rifle since I started loading for the M1 about 30 years ago. Heavy bullets and slow powders were to be avoided! Modern sporting ammo was to be avoided. Additionally, the Speer manuals always indicated rifles with powders with suitable burn rates for service rifles, ie, M1 and M14/M1A. More recently, was it Hornady (?) that marked a line of ammo "suitable" ammo intended for the Garand, implying (in my mind anyhow) that sporting ammo was indeed not appropriate in the M1?
Am I reading OP correctly in that most of that is now hoopla, according to the "ballistician".
While sounding a bit high toned, the research at casual glance to my simple mind, seems thorough.
