Say you spotted a typical sniper team consisting of two crew members, one gunner and one spotter, and it’s just you alone. You need to minimize your chance of being killed while killing these two. Their are within the range of your gun, and they are actively visually scanning the area too, so return fire is a possibility.
So what is the standard military technique for this kind of situation, who are you supposed to take out first? The spotter or the one holding the gun?
I would think that the guy with the capability of shooting you is always going to be the highest priority target. What’s the spotter going to do without the shooter?
I am sure that a military person who has a factual answer to this will weigh in, but meantime, I am not familiar with sniper strategy. Wouldn’t a spotter be armed too? I mean, I would think anybody within spitting distance of combat would be armed, even the cook.
Depending on the team, the spotter is almost as good a shooter as the sniper and they trade off duties.
I would think you’d shoot whichever was the easier target to hit. The last thing you want to do is give away your position by shooting and missing. Once you’ve killed either one, the threat is not entirely gone, but has certainly been degraded in capability.
Spotters are, I believe, the more experienced of the two. They are armed, but not with a sniper rifle.
That may be true, but if the shooter gets hit, I doubt the spotter is going to jump on the gun. He has an injured buddy and his position is compromised. My guess is he/they are heading for cover.
Take the guy whose finger is already on the trigger. Then you can re-aim while the spotter panics, moves his friends body, gets behind the gun and starts looking for you. More likely, he’ll get the hell out of there.
Check their location on my handy-dandy map, and call in artillery, or an air strike.
This, while running away.
I can only speak anecdotally, having worked with some snipers before. My understanding is that the sniper and spotter are both equally experienced and trade off doing both duties. I would agree that the guy with the gun would always be my first target as he is the bigger threat. As to whether this is proper technique, I have no idea. Even then, I would only take the shot if I was in an ideal position to do so as I’d likely miss and reveal my position since I have no training in their techniques.
And when I say ‘ideal’, I mean 1) have no other option 2) no wind 3) sniper is forced to shoot into the sun based on where I am and where he is 4) I am well concealed in a dark environment with lots of heavy/thick materials to hide behind that his bullet won’t penetrate and 5) I have excellent vantage points to shoot from.
But yeah, the airstrike sounds like the better option…
Yeah, airstrike, artillery or tank gun is always the best option.
Barring that, I’d pin them with suppression fire while the rest of my team advances. If I’m alone, and running away is not in the cards, I’d try to sneak up on them and take them out at close range, preferably with grenades. Whatever I do, I won’t try to shoot them at long range. Long range is where snipers live.
I’d go for the shooter too, but since the OP didn’t say he/she needed the answer fast, I assume this is a hypothetical, so…
The spotter might actually have higher odds of seeing your shot. The spotter will be scanning with a spotting scope or binoculars as well as the naked eye while the sniper is likely looking through a rifle scope with a narrow field of view. It’s possible that the spotter could see where you’re shooting from and grab the dead sniper’s rifle and return fire while, if you shot the spotter instead, the sniper may not see where it came from. That’s a gamble though, there’s no way you could know, so going for the guy with the gun in his hand is the only thing that makes sense. But it’s not foolproof. The spotter might pop you a second after you shoot his buddy.
As a devout coward and former MI professional, I would like to endorse this option.
Otherwise I take 2, maybe 3 shots:
Oh no, you do not want to run. They will see you and shoot you before any artillery shells or bombs can be put on target. Your want to duck and cover. Under a grade school desk if one is handy. 
Both but sniper first?
If you can get off your first shot without it being spotted by the sniper team wouldn’t there be a good chance of firing your second shot before the unhit member of the team can react? You have the flight time of your shot plus the reaction time before his response until he even starts to move.
My intuition would be if one presents a markely better target, hit that, if thery’re about even, hit the shooter.
Let’s turn it around, if your sniper team takes fire, and your spotter is hit, what’s the procedure there? Return fire, render aid, seek cover? Probably context driven, your call.
Don’t try to run, you’ll only die tired!
I say nuke them both from orbit. It’s the only… well, you know.
In sniper school*, we were taught:
If you are facing this situation, chances are you are the wrong punch line of a joke, so try walking into a bar, with a Irish priest and and rabbi, if available.
Always duck, so you don’t walk into the bar.
Kill the spotter first. He’s also a sniper and the fact they are still looking around means either (1) they haven’t located you, yet, and shooting the spotter will impede identification; (2) they have located you already, but are looking around for other people walking into bars, so shooting the spotter will determine if you are in the right joke; or (3) they have forgotten correct procedure, which is to eats, shoots and leaves, so it suggests the sniper is confused.
*I lied. My entire experience with sniper school was listing to my friend BS about the time he was in the army and was sent on a sniper mission. His girlfriend didn’t believe him either.