Oh I was not trying to say that CDPR should use the idea of with enough shots any armor could be broken for their game... I was only talking about this because it's a fact. Essentially I was being half off topic, because I was talking about real life, and not how it might or might not be in the actual game. XD
And I know that calibre alone is not everything, which I did say in my post. I only took the 9mm as an example for the general punching power your average 9mm might have.
As for complexity of implimenting it... I don't think that it needs to be all that complex in the game though. Just give every type of ammunition available a statistic which effects the armors protection value only, a statistic which lowers the armors protection value everytime it hits armor. So while the armor might at first have a certain protection number which lowers the incoming damage, when hit with ammunition X it's protection value will go down with let's say 10% (does not need to be %, I am only using % as an example), but when you use ammunition Y it might go down with 25%... because Y was made for punching through armor.
I would not mind if they used a system simmilar to
Brigade E5 and it's sequal
7.62 High Calibre, or any of the other sequals as well (think there are 4 or 5 games in total). Those games system do to one degree or another work like I mentioned above. Heh... I keep bringing up these games on this forum... because they are, in my mind, the most realistic game I have ever played when it comes to combat... especially when it comes to the effects of combat, and being shot at (even if they miss), being hit with various kinds of ammunition, etc. Just the fact that the game keeps track of your characters adrenalin levels in a fight as well is cool, because even there it is pretty realistic. High adrenalin and your characters chance to hit goes down, but the speed at which they get of each new shot becomes faster... low adrenalin and your hit chance goes up, but the speed of which they get of a new shot becomes slower.
A spike of adrenalin has at times saved my characters in these games because they managed to squeeze of a shot that little fraction of a second faster then the opponent did. Which is relevant, because if a character is hit by any type of thing in this game, then it shocks the character for a little bit, halting their action for X amount of time (depends on what it is really, and how hard of a hit it was, etc). Of course, the kind of weapon your character is holding, and the characters stats and skills, effects the speed of firing more then adrenalin does... but sometimes those fractions of seconds, that adrenalin will change, make all the difference between your character being dead or alive. Suppression actually works in this game partly thanks to adrenalin as well... because on top of it makes the enemy take cover, it also raises their adrenalin levels so that they have a harder time hitting your guys when they do fire back.
It also means that every kind of weapon in this game has it's usages... even the games worst pistol can win over someone with the best assaul rifles you can find in the game... as long as your in somewhat close range of course, because the pistol will always be quicker to get of a shot with compared to an assault rifle. But the assault rifle will close to always win against someone with only a pistol if your at medium to longer range, due to the accuracy issues a pistol can have at longer ranges (you/they can get lucky of course and hit anyway with the pistol at longer ranges, and a headshot is a headshot after all... even if the helmet maybe did take the brunt of the hit). That is why all my characters in these games always carry a main and secondary weapon... usually some kind of rifle as main, combined with a pistol or a smaller smg as secondary (maybe a shotgun, depends on what I am going into really, and how strong the character is). Because sometimes it's a bad idea using rifles, even if it does put out a lot more damage per hit compared to pistols or smg's, especially when going around corners and being in close quarter fighting indoors, etc.