How much detail is good enough detail?

Looking back at modern warfare RPGs I've played and examining their "detail" got me wondering what's important and what isn't. Is the exact caliber of the gun important? Might be if you have to scavange for ammo. Caseless ammo was a very uncommon item in Twilight2000. Yet it didn't portray any clear tactical advantage I couldn't use in the game to roleplay a scenario. Overall ballistic detail was not adding tactical realism.

More so how do we arrive at such ballistic detail? Through mathematics and models and number crunching that, in the case of simulationist warfare RPG, calculates the bullet trajectory, momentum and impact location.

What does all this work lead to? Does this added detail and workload actually lead to some effect in role playing? When I played Twilight2000 I felt like a submachine gun was just the same as an assault rifle and pretty much like a light machine gun. Sure, there were damage and ammo differences, but when I rolled once to hit with an assault rifle and rolled once to hit with the machine gun it felt all the same. I didn't feel like I was firing a fear inspiring weapon. I always heard it was important to take the machine gunner out first. I wondered why? I felt just about as unimpressive as when using an M-14. A documentary I just saw mentioned that a soldier with a BAR or a machine gun was worth 10 riflemen. I quite didn't feel 10 times more powerful or relevant in an advance on the battlefield than my fellow players. Calculating the exact parabolic trajectory of the machine gun round, finding its exact range and momentum, its impact point and damage, adjusting for recoil, wind, and what not was not making me feel more impressive. I needed something else.

I begun looking elsewhere for detail. I'm designing weapons based not on math, but on experts. Documentaries and people who've used them and told me how they respond. From videos and research I've done on how these weapons are used, their advantages and disadvantages. I'm dialing in the numbers into a program and getting the modifiers I need by a means of regression. I work with these numbers until the weapons feel right.

I strongly believe a game can be simulationist without being "number-crunchinist". There's more to detail than the exact trajectory of the bullet. I've found that a lot of detail and realism can be filled in by the mind itself if simple easy to use models are presented and complemented with other equally important aspects of modern warfare. Fear of being shot at. Responding under pressure. Unknown enemy size and location. Really deadly encounters that require the player to move, cover, relocate and find new strategies. All these are aspects that are sometimes left as an afterthought or enjoy less "detail" or "realism" than the bullets and weapons. Nonetheless the level of detail and realism portrayed by these less glamorous aspects of the game enable or disable a huge set of role playing options for players.

A certain initiative rule, a limit on attacks per round, how a often and quickly a character may move, or simply the need to see a target to resolve combat rolls may change the way the game is played in such a way that makes it much more unrealistic than having an error on the exact range of a weapon.