You might try adding time constraints to add an element of stress. Another way is to make vigorous exercise before shooting the scenario under a time limit. An example is to make the shooter run 50 yards and then shoot a scenario in 10 seconds or less when he/she probably couldn't make that time to start with.
Have the shooter turn his/her back and change the scenario to add elements of surprise and include the time constraint.
Figure out a way to score your scenarios and worst score buys coffee (or whatever). A few of these will get people to improve so they don't have to pay all the time. Any element of pressure will help the shooters prepare for a time when there is a lot of pressure.
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