I can tell you what works for me.
In my experience,its not just the scope. You will be looking through 300 yds of air. By that,I mean every day is different. Lighting and mirage play a part.
On an exceptionally good day, with my scope I can see 30 cal bullet holes in the black on an NRA Bullseye type target at 500 yds. But I don't count on it for every day.
My preferred sight in distance for some of my rifles is 300 yds. I do shoot and spot targets at an actual 300 yds.
Walking downrange to check 300 yd targets eats a LOT of time. Your 22 cal holes at 300 yds was my criteria,too,when I bought my scope.
I ended up calling some back east discount camera and optics joint. The salesman told me he had a trade in I could have for a good price
It was a Kowa Proimar with a 77 mm objective and a flourite crystal objective lense. It came with a 20x to 60x zoom eyepiece. I'm VERY happy with this scope. It exceeds my expectations. I can st my 300 yd targets and do all my shooting without going down range till I go pick up the targets. It works particularly well with the orange on white sight in targets.
The max power that you can take advantage of is tied to some other factors. The 77 mm objective on this scope gathers a lot of light. It can use more magnification than a 50 mm or 60 mm scope,for example.
With this scope,under most "good light" conditions, zooming to about 40 to 45 X is about the max that gains me anything. Sure,60 X is "bigger" but resolution is not necessarily better. Some days I wish I owned a fixed 30 X or so long Eye Relief eyepiece,too. IMO,that would be useful for checking a target without disturbing my position.. FWIW,My scope has the angled eyepiece. That works for me. The scope body "barrel" has a little rib cast into it that is good for pointing the scope in the general direction.
Another thing is training your eye to really "look" . Its like listening for the faintest sound when you are hunting.You look "deeper" than first glance.
At least,thats what I have to do.
I'd certainly buy another Kowa without reservation.
If you look on E-bay, there seems to be a KOWA distributor or two who list there.
Another scope I got lucky on, and certainly buying an old,used optic off e-bay has its risks, for about $100 I bought a 1930's Bausch and Lomb NRA model scope with a 20X eyepiece. I really am impressed with the old B+L.
At only 20 X , I won;t say its dependable to resolve 22 bullet holes at 300 yds. Maybe on a good day. But it IS dependable to see at 200 yds.
A unique and useful feature of this scope is how the eyepiece focuses. It has a series of detent "clicks" that you can rapidly get a near focus with,then fine tune by turning the eyepiece. I figured out that with a sharp focus on the target,pulling the eyepiece back one click would focus the scope at the mirage just in front of the target. Very useful for wind estimation. Then just push IN one click and the target view is sharp.
This scope is generally similar to the GI M-24, but smaller,shorter.