The hardest skill tree to build. No matter which path you go down you are making sacrifices. Despite that there are some very solid options for the Veteran. The class has more ranged options than anyone else and can make excellent use of these choices and makes short work of enemy gunners.
Use your regenerating "Krak Grenade" to kill heavy armour, and your gun to shoot everything else. This loadout is one or two points away from a lot of high value skill points, but this is what I have settled on. Picking any of the other points would sacrifice other talents that I am unable to give up.
At first glance picking the talent "Only in Death does Duty End" seems like an obvious choice to pick. Being able to revive teammates with a simple button press seems obvious. However, I think this build is much better off not grabbing this choice. There are a few problems with this choice. The first and most obvious is that it greatly increases your cooldown and limits your range. This makes the shout pretty bad unless someone is already down. Additionally it promotes passive gameplay, where you aren't buffing your teammates until it is almost too late, as someone already went down. When you skip this talent I find it best to use it almost on cooldown (unless there are no enemies around). This lets you restore thousands of toughness throughout a match, and has decent up time where all or most of your teammates have increased damage against all enemies. "Focus Target!" is highly spammable, and you will constantly generate your team toughness, as well as giving them constant damage buffs.
Press ability. Shoot highlighted enemies. Repeat. That's the entire game play loop for this build. If you have crit chance on your lasgun when you build this talent, you basically have unlimited ammo the entire match. The giant ammo pool as well as free crit bullets makes it so you can stow your melee weapon and not worry about a thing most matches. Any Helbore lasgun works great here. The MkIII does the most damage and gives you the most "sniper" potential. When onslaught is fully charged the Mk II shoots nearly as fast as the Kantreal XII. If you don't like the charge weapons, or can't seem to get Onslaught then feel free to bring the Kantreal XII (or one of the other lasguns).
The Plasma Gun is basically the Plasma Cannon. Just don't forget to bascially always hold down the special key so you don't go boom.
Another very good, similar build would be to dropthe two bottom nodes in the middle branch "For the Emperor!" and "Bring it Down!" so you can get "Agile Engagement", located on the far right below "Smoke Grenade". This build naturally swaps weapons a lot, so that skill is very good and gets constant use.
The "Krak Grenade" is easily the flashiest blitz on this skill tree. It will kill a crusher in one shot on T5 difficulty. However, it only hurts carapace armour, so it is harder to use than the other blitz. For that reason on most of the builds I like to stick with the "Shredder Frag Grenade".
Stacking Toughness is good on Veteran. I like to take two toughness curios and one health curio. Changing out the health curio for a stamina curios is good too.