Hook686, I had a look in my loading manual and all I could find was CCI-400 and 450 primers for pistol and CCI-400 primers for rifle. Double check me, but aren't those small pistol and small magnum pistol primers? 30 carbine loads have a 40,000 CUP SAAMI rating. Hornet loads using small pistol primers and Lil'Gun are listed as 41,500 CUP - again, double check me!! If I am right, then it would seem you can use small pistol primers. BUT, please, several posters have cautioned against it for two reasons. On the pressure issue, I would suggest using load data specifically stated as being for small pistol primers and for 'slam-fires', well, what can I say? (IMHO, no gun should ever be susceptible to any kind of malfunction!) Doesn't the M1 30 carbine have a floating firing pin?