If there is no movement between the hinge pin and the corresponding "hook" the gun could not open. There is some and that small amount of movement will be magnified over time. Try to take a new wheel bearing and find lateral movement in it and there is essentially none (typically a few thousands) but it is enough to allow rotation - but also enough to have an issue with impact pressure, which is what bearing greases are designed to do. Calculate the pressure of firing on the relatively small effective contact area on the hinge pin and you will find extremely high pressure effects, although for very short times.
Can virtually any lubricant work - yes but not optimally. That is why there are a variety of lubricants that are available. You can choose to use them (or not) and prolong the life of your firearm as you choose.
Thanks
Z
