I attended the Op. Red Storm East in Scranton PA, it was an extreme CQB that was semi only and 366 FPS with .25's and I have to say that it worked extremely well for indoor use. Taking rounds from 3-5 feet away were not really bad (except for the three I took to the forehead because I leaned out too far), people really tried to aim for center mass when they were that close. Personally, I think it would work much better to have one FPS limit for the entire Op - indoor and out. This will cut down on people crying because they think someones shooting at them with a hot gun, and its more realistic then ripping someone up with a high speed gun. Or people having to bring two primaries on them.