Am new to reloading and have been able to purchase large rifle, small pistol and large pistol primers. Have had a hard time finding small rifles primers which will be used exclusively in an AR-15. I have found some Remington 6 1/2 standard small rifle primers but have read not to use them in .223. Is this hype or would it be safe to use them, especially since they are the only small rifle primers available?
I comprehend how a projectile can, “lose velocity", but don't understand how a projectile can, "loose velocity".