The weapon effectiveness can be an overwhelming topic, but you must know at least the essentials to survive, let alone succeed well. But you've already found out the trigramreactor wiki so you're on a good start. Take for example BO auto-sniper rifle:
https://xcf.trigramreactor.net/master/article/STR_BLACKOPS_AUTO_SNIPER_RIFLEThe key things to look out for here are:
- what is the damage type, i.e. KINETIC. This is what most 'classic' guns do. If you compare the effectiveness of various guns against enemies, you should check if some are particularly weak or strong against some damage type.
- how various stats affect accuracy (ie. you need good accuracy, at least 90 to use it effectively, preferably 100+)
- how accuracy boosts the damage (ie. with 100 accuracy you have the base damage of 50, and with 50-200% damage spread you could get more - this is among the best with easy access KINETIC weapons)
- how the weapon penetrates armor (armor efficiency of 0.75).
Compare this to UAC rifle. Against 30 armor, in average UAC rifle does only a couple of points of damage. But BO auto-sniper with 100 accuracy deals in average about 30 points of damage. So while you might not one-shot heavily armored foes, typically at most two shots with a sniper rifle will kill most enemies.
There are also many other parameters, but these should get your started.
I've myself found the gun simulator way too cumbersome to work with (you need to input too much information) and haven't bothered with it.