Pistol grip and model 500 don't go together well. I seems it would be better without a round in the chamber and the safety off. You then hit the disconect which is in a good place on the 500 and rack the weapon. Seems this is going to be faster then fumbling with a PG model 500 and tang safety.
Also, a sear works as designed but I doubt it would be designed to hold in the violence a car crash. I don't consider any weapon being transported in a vehicle in any type of case as being safe with a round in the chamber.
J.D. McGuire, Owner
AI&P Tactical, LLC
Remington Factory Certified
Law Enforcement Armorer