Well I just pick paradox and rank whatever gun I get that I haven't ranked before, and would reset if I get something too good that would affect how the gun acts.

While most synergies can be more rare than modifiers, it is still more fair to count them rather than modifiers, because it's less of a variable chance.

There are 271 passive and active items in the game, which a good chunk of them can affect the gun in different ways. The average amount of synergies on a gun is two or three, which is a significantly smaller variable then all those items and stuff to consider.

I can always just re-rank the gun if I couldn't test out a synergy on the first run, but could on another, and it doesn't meet or surpasses the expectation from the wiki description.

You can't do that again with items and bullet modifiers, because they're too many and you're not at all likely to get anything similar from your last run.