Thanks for your reply Baggins.

What you're basically saying is that everything is relative to everything else. Lets say for example however that my character is 5'11" then if I had some kind of ruler I could scale the gun to say, 6" or whatever the actual specs are.

The problem is that I have no idea how big some props are. When I import them at 100% they're either really big, or really small. Just this morning I imported a car, and it was 100%, but looked like a remote control car next to the model. I scaled it up 350% but I that was nothing more than a guess.

If I could put something on the ground that would represent 1 foot, or whatever, then I could scale everything to that measurement.