Quote Originally Posted by Bruce McAskill View Post
The specs on the .30 carbine was approx. 1900 fps. max effective range was 300 yards with a velosity of about 850 fps. The same as a standard .38 spl round. After 300 yards it began to loose everything. When Johnson converted carbines over to .22 cal. the best he could get with proper pressure guildlines was a light weight 40gr. bullet at 2800 fps. The US military was looking at .22 cal. rounds at that time and other rounds with a hevier bullet and higher velosity were already being studied. As someone else said he was a little too late to the party.
Yet now the 5.7x28 is considered "good enough" but the 5.7MMJ (.22 Spitfire) is far superior.