For Mechanical Zero, do what Kraig mentioned in post #2.
Sounds like you have target turrets, you don't need "Tactical" turrets, whatever those are (I am guessing target turrets without a cap and a higher price tag).
Do a box test with your scope and see how well it tracks. Set up at 100 yards with a good rest, and shoot a group, go up 10 MOA and shoot another, then right 10 MOA, then down 10 MOA, then left 10 MOA. The fourth group should be on top of the first. If you have a large enough target, 15 MOA for each step would be better.
That should give you a good idea of how well the scope tracks.
If your elevation is OK, and you shot OK at 300, my guess is that your scope is not far off, if at all, and most of the problem is reading the wind.
For wind, were you adjusting the scope, or holding off? With Mil-dots, it is pretty easy to hold off, you have handy reference points. Keep in mind, that for a variable power scope, unless yours if first focal plane, the mil-dots will only be 1 mil at a specific magnification. For my Leupold it is 10X, which actually works out OK, because it tops out at 20X, so the mils become half mils.
Start here, thanks to the Army Marksmanship Unit:
https://www.youtube.com/watch?v=nAYqr02dpQ4
She gives a pretty decent high level overview, and a great place to start.
What I did is print out a cheat sheet and taped it to the sun shade on my scope. If I had to do it over again, I would laminate a range card and hang it from the front scope ring, so I can see it from behind the rifle.
range /drop/10 mph full value wind MOA
100 +1.5
200 0 1
300 -2.2 1.5
400 -4.7 2.1
500 -7.6 2.7
600 -10.7 3.3
700 -14.1 4
800 -17.8 4.7
900 -21.9 5.5
950 -24.1 5.9
1 Mil 3.4 MOA