Power of spotting scope

Is there an acknowledged minimum power for spotting scopes? I've seen some 10x monoculars that I'd consider using on my box, just to keep the weight down. However, I don't know if I could see the .22 holes at 50 yards. Any ideas would be appreciated.

22 holes at 50 yards depend more on lighting and optical clarity than magnification.

Typically 15-20x is the normal power for a bullseye spotting scope. 10x would be fine at 25, might be a little weak at 50 yards.

If the objective is large like 60-80mm with decent glass you can see them easily at low power. As your objective gets smaller and glass quality goes down you lose light and resolution. I would never use a monocular at 50 yards for 22lr. I would personally recommend at least a 50mm objective spotting scope wirh decent glass. What's your budget.

Started with a Barska - cheap and cheerful, but hard to see anything well at 50yards. Others on the line at local matches use Minox MD50W - about $200 - great at 25 yards, but in bad light I struggled to see 22 holes in the black at 50yards.

Tried and returned several bigger and more expensive scopes, eventually settled on an Endeavour XF80mm for $400 off Amazon. It is great in all light conditions. But it is quite big and heavy - it fits in my Bullseye box, but only just!

More recently I tried one of those tiny NG scopes - from the Canada dealer, see other threads on this forum - but not good for my eyes. Returned it.

Champions's Choice have a good selection of scopes at fair prices and are recommended by many.

I've  never had a problem seeing 22 holes at  50 yds  with a 10 power scope. I don't have any with an objective lens over  50. They won't fit in the box. I think it all depends on the individual.

I have the scope that is in the link. Great glass, 45 angle, no issue at 50 yards. Power easily adjusted as is the focus. Good range of magnification. Light weight. VERY compact. Free returns too.

https://www.opticsplanet.com/hawke-sport-optics-nature-trek-9-27x56-spotting-scope.html

A lot also depends on the range and how the sun hits the targets early in the day when we usually shoot 22. If you think about it the first 30 shots we shoot have the worst lighting and are the hardest shots to track.

The smaller the scope gets the more you'll be able to see flaws in the optics. If you've got the budget get a decent scope, they basically last forever. I got a 50mm Vortex Razor which is their best, I don't regret it. Either way I wouldn't recommend a small scope under $100 if you're gonna shoot 50yd regularly. 50ft and 25 yard is a piece of cake.

For 50 yards you need at least 20 power magnification to see the holes. 25 or variable would be better.

The Kowa TSN-501 from Champions Choice is a perfect scope for bullseye.

I have had a Bushnell Sentry 20x since the 70s
Back then I also used it to spot my Outdoor Prone 100 yard matches. 
It is still a great scope.  
 Sometimes I would spot with the big green Bausch&Lomb
It is better at 100 than the Sentry.  Definitely better at 200

I have a 10 - 50X spotting scope from Champions Choice, angle eye piece has to be at least 50mm. It's not very big, it fits easily in my small 2 gun box. On most days I can see .22 holes at 50 yards, yes anything in the white is easy to see but on those dark rainy days .22 does seem hard to see those in the black.