This is the build that i finished the game with on hard difficulty with oddities XP system
http://underrail.info.tm/build/?AwGloJgVhBmEDsi4gIwDYVPG2MeoSirCgCcm6oVIU8JxptMDawqYnOBI0vSsACxwAHHDIhBYqBzq1MCGAkwkVEEUAYou can drop Hypertoxicity feat (it's mostly useful for killing certain creatures in foundry), instead i would recommend taking Kneecap Shot feat or anything else that is to your liking. Also you can reduce biology to a level you are comfortable with, 80-90 is pretty good, you will be able to craft most poison bolts and useful drugs in the game. Just be careful so that effective chemistry skill won't drop lower than 75 (it will make your end game a bit easier).
If you don't use oddities system then pickpocket isn't that useful to you either. You can distribute free point to either Dodge, Throwing or even Persuasion, depending on where you want to go with this build.
Personally i used smart goggles to enhance damage from special attacks like Aimed shot and Snipe and it was more that enough to stay with pretty good damage for the entire game. But you can go for critical hit route and take Recklessness feat, seeker goggles and infused rathound leather armor.
With pneumatic cyclon crossbow, special tactics and use of an adrenaline, you can shoot 5 bolts in the initial round, two of which will be special attacks, in 90% of the encounters it is enough to kill/stun most of the opponents.