I was wanting to get an ST-6 before they did away with the fixed and went strictly with the variable 1.5-6x, SR-6.
Now, in your position, I would go with the ST-10. That's what I use on my tactical bolt gun.
I like the fixed power scopes as it's one less thing to mess with. Get used to hunting and shooting on 10X and you'll find finding your target, without having to zero in on it at low power, much easier.
I will say that, as noted above, there is a lot of scopes out there that can fill the bill for you, for less money. Scopes with good glass and variable powers. I see getting top notch glass in several brands, but the biggest thing you'll get is a personally chosen 'most usable' reticle with USO. That's the really big advantage with USO. No one offers the reticles they do in a standard scope at the same price. Top glass, best reticle choice.
Now, again, that said, you can get other reticle choices that can work. I've used the NF NP-R2 reticle. In fact had it not been for the reticle I could not do what I planned to do. That scope got sold however as magnification was too high with it. And no where near enough travel.
So, bottom line for me is, that is a lotta scope for the minimal distance you plan to shoot. But, I make my case for USO for the said reasons. You can get a lot more features on lower priced scope but no where near the reticle selection with lesser priced, more variable scopes. Which IMO will work just fine for the ranges you suggest, but start to lose out when you stretch your selected range out to what your rifle will shoot to. Lot's of people never get the best they can for a few dollars more because, "they'll never need it." It's a mistake. If you get too much scope without being able to short range it, it's a mistake as well.
-good luck with your choice.