I'm looking to buy a new red dot sight for my Sig 522. I'm looking for something cheap (<$50). I see a lot of the sights have MOA's of 4 or 5. I've looked up the definition of MOA and I know it's about 1" at 100 yds. Can anyone confirm that the MOA number means how big the red dot is in the scope at 100 yards. Basically, how big the actual dot is in the sight? So, for a 5 MOA sight, the dot will cover 5" at 100 yards?