Ok,
My best advice at this point would be to:
cut crafting feats + salesman
get instead:
ambush
critical power
throwing + grenadier (30 throwing 6 dex)
rapid fire (great for pistol sidearm if that's what you want
gunslinger (great for pistol sidearm requires 7 dex)
spec ops (6 agi, great for smg sidearm)
increase stealth since it affects snipe damage + unlocks ambush feat which you may find very helpful
take skill points out of biology (or even better, dodge because ideally you want them at a distance and you can get uncanny dodge with only 40 points invested + goggles which are optimal for gunners reduce dodge by 25%) in order to unlock a second combat ability. You are gonna want throwing or traps as a backup to your sniper and pistol when:
-there is a huge horde of enemies that can't get blasted down fast enough
-someone is closing in on you and you want to drop a quick tinkering trap (7 dex for feat)
-you have traps set up before combat that are hard to see for enemies which you can use to trap them in bad spots/ out of line of sight of you. (fyi you can use beartraps with 0 skill, animals don't see them, and lots of people will run into them if you put them around a corner because they will have no time to spot it)
Also some of your crafting skills are a bit too high, you're not gonna get components that high quality unless you REALLY GRIND
my version of this build looks a lot more like this:
http://underrail.info.tm/build/?GQUGCAUMAwfChzoAACjCh3BkZAAAaGgNKGgAAAAAACMkAU8ZOTVBM0sCWxZZUw(FEATS NOT IN ORDER BTW)
If you don't mind reloading those 2 points in con aren't gonna save you from SHIT anyway, so you may want to just dump it completely and put those points into more per (missing with sniper HURTS BAD MAN)
That's my best advice methinks. Good Luck!