I don't think a guns build is every going to be too powerful especially not compaired to some builds out there, for instance I once did a Geralt of Rivia build using crafting and swordsmanship, I went around with about 15, 10 shift blocks (Quen), 8 weapons rating 8 zone wide bombs (grapeshot) and many , many potions up too the level that I could add +12 to my roll in two turns (two potions of 3 aspects each Thunderbolt and Rook) oh and some magic swordmanship as well.