A little off topic but I can tell you that in one of my ar15s with youngMF national match expensive ass BOLT when I charge and load the weapon if I eject the shell I can see a pretty deep primer dimple and they are reinforced primers. I have not had one slam fire but it is kinda dis heartening to say the least.
I have had 2 ar-15s slam fire on me over the years and one Galil sporter do it.
The one theme that I heard over and over is to make sure the firing pin is dry. It should not have any oil or lubrication on it at all. The ACR has a return spring, but your Colt does not. Another popular fix for that, is to reduce the mass of the firing pin by using a titanium firing pin which is lighter, and less likely to strike the primer. When it does, it produces less kinetic energy due to reduced mass.