I am a lvl 9 with 6 STR (5 + 1 STR implant) and 65 Guns. The Mysterious Magnum and That Gun are supposed to have base damage stats of 42 and 18 respectively. However when I check the stats in my game, the full conditioned weapons are only 34 and 14 respectively. Whats going on here?

You're guns skill isn't high enough to max out the damage.

You're weapon damage changes with it's respective skill. Mostly the damage presented is that with a skill of 100.

ah I was under the impression that meeting the minimum stat requirements was required to have those stats

Meeting the minimum reduces sway (and spread?). Also, keep in mind that max values also include modifications you can purchase. And then certain perks can increase damage but those are not usually included in the calculation (Lord Death, Bloody Mess, Cowboy, etc.).

Nope. I think the total skill is used to calculate a fraction and with skill 100 that fraction becomes 1.