2moa, but if 100yds was my goal, I'd go optics, no question. Probably a compact Leupold.
You will be able to call your misses with optics. Not so with reddot.
Slacker, I am about to agree with the scope. By the time and money you have to spend to get a red dot that good you could have bought a fixed power scope.
Agreed with the above...In my limited experience red dots are best used for up close quick shots. They can be accurate out to a very long distance, but precision is not their forte.