We service around 200 different departments. We have a Sig Sauer P226 and a Glock 17 that have been modified to attach to a CO2 compressor that operates the slide and simulates about 80 percent of the recoil of a 9mm pistol. We also can put a laser insert into an officer's own service pistol but the CO2 compressor requires extensive and permanent modification of a sidearm. Recoil does two important things. First it adds to the realism, throwing the officer's aim off and making them re-acquire their target.
Adrenaline is key.
If it wasn't for the adrenaline this would just be a big video game. From a physiological standpoint we want as much adrenaline present as possible. That way there's a better transfer of training to memory. This goes back 30,000 years. When you learn something in the presence of adrenaline it is probably a lesson you need to survive.