yes it is possible, 10% bonus dmg from racial traits and then with crit severity, tac target optics buff, 25% dmg from large power cell and add in any debuff on you and bam 1 shot. 1 shots are extremely common up until late commander level when the player hp/shields/armor start negating more of the incoming dmg.
At 6:35 you will see me at Commander level crit for 995 Somewhere in that video you will see me crit again (without my target being exposed) for 1,195 Damage. That was back when I was at Commander. At Lieutenant I was Critting for close to the same amount. Yes, a skilled Tac player that knows how to build his character and knows how to use the tools available to him/her can and will snipe you for that amount.
That's commander level which means there's a few more (and stronger) buffs available than at lt lvl, two extra tiers of skill which (if tac) boost weapon dmg specifically so a 995 crit isn't that surprising.
this is at lt lvl, no crit, not exposed, 700+ every snipe shot, much less skill stats to buff dmg. Litterally a 1 hit shot through full shields and HP, every time.
If it was every single shot, then it is not possible. No crit? No expose? I can promise you that is not possible. If it were possible, I would have discovered a way. My damage is soft capped. There is no possible way to make 700 damage with every single sniper shot at that rank without a crit.
If this is truly what happened, then somebody has done something they should not have in order to exploit the game.