ME1 Optimized Shotgun Vanguard Build

That looks fine to me.

If you are willing to try and solo the game if your squadmates go down, you can drop the 4 points from Spectre Training and use them elsewhere: 1 point in Throw for Advanced Throw, 1 point in Tactical Armor for Advanced Shield Boost, and two extra points. At rank 6, Warp is Advanced Warp, correct? Maybe put the extra 2 points into Tactical Armor for more damage protection.

Throw is not that good, but Advanced Throw is certainly better than Basic Throw which is terrible. I hate wasting points into Throw just to get Pull. Later in the game, once you get better equipment for you and your squadmates, you will hardly be using Unity at all, and by the end of the game you can pretty much solo anything anyway, so Unity is not needed. Unity is nice early-game when you have poor equipment and few talent points, but without the ability to re-spec you kind of end up stuck with those points late in the game.

Please note that using Carnage will cause Barrier duration to end prematurely. This is a bug in the game.

Anyway, those are just my thoughts.

Another option would be to drop Barrier to Advanced (rank 7 I think?) and put those points into Throw. I prefer Master Barrier myself, but between the Shock Trooper cooldown bonus and Adrenaline Burst to reset your cooldowns, Advanced should be good enough. Just another option.

I decided to change the build after reading a lot of analyses that suggest pistols really are the best way to go. It's weird to not use the Vanguard's signature weapon, but the numbers apparently show that pistols are ideal. So the new build is the following:

Pistols - 12
Shotguns - 0
Assault Training - 12
Tactical Armor - 8
Throw - 12
Lift - 12
Warp - 6
Barrier - 12
Singularity - 12
Shock Trooper - 12
Spectre Training - 4