5.56x45mm. It is dimensionally similar - but not identical - to the .223 Remington.
The M4A1 carbine is chambered for the 5.56x45mm NATOcartridge, the same as the assault rifle it was derived from, the M16. It is also capable of firing the .223 Remington sporting cartridge.
5.56 x 45 mm
10 years in prison. The M4A1 is a fully automatic rifle, made after May 1986, and cannot be possessed by private citizens.
Yes
3.2 ft-lbs. That is more than a .22 rifle, but less than many others. PS- my grandaughter shoots one of my AR rifles (same caliber) and she is 15.
$1,032 per rifle according to the DoD
a .22 caliber
A .177 caliber air rifle has very little recoil.
Only with a Prohibited Licence can you own a full auto firearm (which the M4A1 is). A semi-automatic AR-15 would require a Restricted licence.
.223 caliber or 5.56mm.
The barrel length of the M4A1 carbine is 14.5 inches. Legally, it would be considered a short-barreled rifle by the BATFE (Bureau of Alcohol, Tobacco, Firearms and Explosives).
No You could build a rifle in .306" or any other caliber but you are likely referring to 30.06. A 30.06 rifle is referred to as "30 Caliber" but to be accurate it is nominally .308"