Serious question here…
So when you’re shooting quickly and you need to transition from say, 600 yards and then rapidly engage a 1 MOA~ish target at 200-250 shooting positionally, how do you set your parallax? Mark it and wing it with your weak side hand? Do you drop it off your shoulder? Break your view down range?
I ran a 3.5x-10 M3 for a year on my mk12. Fine for flat range slow fire or bench shooting. However, when shooting off a barricade, etc. I find it much faster to shoot a fixed parallax scope.
Curious if there is a technique to get a parallax adjustable scope fast like a fixed LPVO outside just setting it at 300 and living with the sight picture/ parallax. (Kind if defeats the purpose) I am not sold on my Gen3 1-10 and this scope is interesting to me IF if will work for my style of shooting.
Some of the others have given you good answers, so I will give you a real-world example:
I had a stage last weekend with several shots alternating between 2 targets at about 200yds and 400yd. The targets were the same size, so the longer one is effectively half the angle. I was using my Vortex Gen II-E 1-6xx. The 200yd shot was OK, as the fixed 100yd parallax is not too bad at 200. But at 400, it is getting very out of focus for my eyes. And it starts to have noticeable parallax issues at about 300 as well, with it is getting very noticeable at 400. For a minute-of-man target, you could live with it. But I need better than that.
If I had adjustable parallax, I would have still treated it as a fixed parallax, but I would get to choose that fixed point. I would have set it somewhere in the middle, probably closer to 400 than 300, or maybe even at 400. I would need to use the actual March scope to understand how it reacts to being tuned to one distance and used at a different one. Either way, even if set at 400, it would be acceptable at the larger 200 target (probably no worse than my current scope at 200), and be perfect at 400 (the more difficult target).
Note that it is also possible, if you really know your scope, to reach up and move the parallax without looking at it. The movement would not be exact, but you could get it close. Whether this, or any time-eating method to change parallax during an event, would make sense depends on many, many factors. It likely would not in my above scenario. With a time limit and a relatively small difference between distances, I don't see that it would be helpful in that particular overall task. Find a good compromise distance (for that particular stage) and leave it. When you get to the next stage, set it for the best compromise for that stage. But I have had times where it probably would make sense to dial in some fasion, if I had the option to dial.
As I said, in actual use I would need to use it and figure out where is the best compromise. Every person's eyes are different, and react to glass differently. What is best for me may not be best for you. But at least with adjustable parallax, we all have a range of options to find the best compromise. When you are fixed, you only have one compromise.
BTW: I had a DNF on the above stage due to missing the last shot at 400. A better sight picture probably stops that from happening. So my one available compromise did not work for me on that day.
BTW2: The very next stage after this one had us taking head shots at about 5-7yds. If we hit outside the target, we got a DNF. So I literally went from one shot at 400yds, to the next shot at >10yds. I would be able to dial down to minimum parallax off the clock between stages, so no penalty. I can't think of a better example where adjustable parallax is an advantage than in that scenario.