Another plus about the polygonal rifling. I read that hk test fired it with a squib load bullet stuck in the barrel. Both bullets came out. While it did cause a minor bulge, the pistol was still serviceable. What more could you ask of a last ditch save-your-bacon weapon?
That isn't a result of the polygonal rifling, it's a result of the strength of the barrels.
Know the status of your weapon
Keep your muzzle oriented so that no one will be hurt if the firearm discharges
Keep your finger off the trigger until you have an adequate sight picture
Maintain situational awareness