Plastic or metal? Full size or half size? It would vary depending on the actual gun you are trying to talk about. Try anywhere from 1 lb - 10 lbs.
No. It is considerably lighter than it's real steel counterpart.
It depends on which companies make the m4 you have, but generally companies stick to the same dimentions for magazines for the m4/m16 family.
m4 there are spare parts
One would be able to find out more information about m4 airsoft guns online on Amazon. Two other sites that have some information about m4 airsoft guns are wikiHow and HobbyTron.
The M4 CARBINE IS BETTER THAN THE M16.
Most airsoft battles take place in close quarters which is what the m4 was made for. Unlike the m16 which was made for longer ranges
yes
Yes.
It all depends of the company making it. A Tokyo Marui M1A1 Thompson would be better than a cheap Wal-Mart M4. But a Classic Army M4 would be better than a CYMA M1A1 Thompson.
almost every gun for airsoft uses a 6mm (milimeter) BB. try that.
Many different companies make Airsoft mac 11 and m4's. However, the M4 models are generally a better all purpose weapon, where the mac 11 is only good for very very close quarters combat.
An M4 is a short barreled version of the M16, so yes, they can look quite similar.