No, in small doses it enhances performance by lowering heart rate, reducing anxiety, slowing breathing, etc. All are important in sports like rifle shooting.
I compete in pistol shooting at an amateur level. I have never been even slightly intoxicated when shooting a firearm. But I shoot 10m air pistol[1] at home for practice, and I've tried it while a little tipsy. So I can tell you that for sure, 3+ drinks will have you thinking you're doing well when in fact your vision is so delayed from reality that you cannot call your shots accurately. You'll think it was a good shot and it was a 7.
But one or two drinks in, there is a small performance boost. It comes from not 2nd-guessing yourself. You just hold on target and watch it happen.
Pistol shooting is a lot about quieting the mind because nobody can hold the gun perfectly steady. You get the best results from accepting a little bit of natural wobble, and smoothly operating the trigger during the smallest part of that wobble pattern. If you try to shoot the gun right as the sights cross the bullseye you will typically throw the shot off badly. Even if you don't yank the trigger, your reaction time is such that the wobble has moved on by the time you react to it looking perfect, so you end up grouping all around the 10 ring instead of in it this way.
The other thing you'll do in pursuit of perfection is hold too long on the target, not happy with how large your wobble is. You end up holding for 10+ seconds and by the time you break the shot your vision is suffering from the Troxler effect[2] and your hold has gotten worse, not better -- you just think it's good because you aren't seeing it as clearly.
It is best to steadily break the shot not at a specific instant, but anytime within your mostly 9-ring ideal wobble area. You settle into this good wobble zone for a few seconds, perhaps from 3 to 7 seconds after putting the gun on target. By Gaussian distribution you will shoot a lot of 10s, a fair amount of 9s, and a scarce handful of 8s.
But I cannot tell you how hard it is to convince yourself to do this! The mind thinks it can make the gun fire when it touches the 10. It also thinks that the wobble is way, way bigger than it really is, and that you'll shoot 7s if you let it happen. You'll even panic subconsciously right before the shot breaks when it looks "imperfect" and twitch to try to fix the alignment at the last moment -- always terrible.
A little depressant makes it much easier to relax and confidently break the shot in that "good enough" zone. Don't get me wrong, it'll never turn an amateur like me (520 - 550, depending on the day) into a top shooter (580+). But it does make it easier to perform on the 540+ side of my average.
I shot rimfire bullseye with my father growing up, but I live in a city now and have gotten away from the hobby. Action shooting takes up all the air in American gun culture; I always found it very calming.
Action shooting is definitely the hotter sport right now. But I think bullseye will stay around, especially as the current generation of action shooters ages into it. It has one huge advantage over action: every competitor can shoot at the same time, up to the capacity of the range. If you go to a bullseye match, you get to shoot for a few hours. If you go to an action pistol match you spend hours waiting around only to shoot for a few minutes.
