This is a little trick I figured out that I think work with all slam-fire Nerf guns, but I found works best with the Strongarm pistol.
Step 1: Cock It
Just cock the gun.
Step 2: 2-Shot Burst
Now's the tricky part. You have the gun cocked, so pulling the trigger will fire it. So what you do is pull the trigger, and slightly after it shoots, pull the cocking handle back again, finger still on the trigger. This will fire two darts in less then a half second, because of the slam fire allowing the gun to shoot as soon as the cocking handle hits the back.
Step 3: Use and Questions
I found this to be very useful in wars where I was outnumbered. I could jump out, fire a quick burst, and jump back down. Also, this would have been a lot easier to explain in a video. Would one of you guys tell me in the comments how to post a video? Thanks!