5.56x45mm NATO, standardized under STANAG 4172, is a rifle cartridge. It is a standard cartridge for NATO forces, and for several nations not part of NATO. It is derived from, but not entirely interchangeable with, the .223 Remington cartridge. This is due to, among other things, the greater gas pressure of the 5.56 mm military round.
What you're asking is impossible to answer here. Firstly, the bullet weights are variable in different loads in the same cartridge. Second, there are powder charge weight variables (different powders, different charge amounts). Thirdly, different brass weights differently. If you have steel cased ammo (for the 5.56x45 and .223) the weight changes yet again. Fourthly, even primers can vary in weight.
There are too many variables to answer this...if you really want to know, buy a cheap balance beam scale and start weighin'.
No such thing.
It can.
The standard NATO cartridge is the 62 grain 5.56x45 SS109.
5.56x45mm NATO
5.56 nato or civilain 223 remington
Depends on the laws where you live. In the US, yes.
Neither. They both use standard 5.56 X 45 mm NATO rounds.
Without question, the .22.
The M4 carbine is chambered for the 5.56x45mm NATO cartridge. It will also accept .223 Remington rounds.
None to really speak of. They are, for the most part, one and the same. The 9mm NATO is merely a variant of the 9mm Luger loaded for military specifications.
I wouldn't chance it, the difference between .223 Rem and 5.56 NATO is 20,000 psi of chamber pressure. With the 100 being a collector piece, I wouldn't take the risk of blowing the chamber or any other catastrophic failure. The NATO rounds have considerably more chamber pressure than the SAAMI rounds.
Aproximately 7 lbs