I play airsoft, and own quite a few guns. Most notable are:
M4A1
M1A1
AK-47
G18C
M9
UZI
M500
And yes, these are 1:1 scale replicas, and in most cases, can use the same accessories the real steel can (e.g. scope mounts, optics, etc.). Airsoft is another alternative to paintball, in which you really want to go for that "tactical" look. Sure beats running around the forest in dayglo clothes with a length of pipe and a hopper in your hands.
Also, airsoft ammo is much, much cheaper than paintballs, and hurts less.
However, there are some drawbacks. First off, airsoft BBs don't have as much energy as a paintball does, and usually do not fly as far. You rely on the backspin of the BB to "loft" them the last couple yards to the target. Since BBs do not leave a visible impact mark, calling hits is a little harder than paintball, and there is room for cheating in airsoft games. This can be alleviated by playing with friends you trust (no "walk-ons"). Third, since airsoft looks so very real, you must be extremely careful where you brandish your weapons. Already, the TV is flooded with news of kids being shot because the police mistook their airsoft guns as real weapons.
If you wish to learn more info, check out the following links:
www.airsoftzone.com
www.airsoftguns.com
X-ring!