Hitting a 50cm target at 50metres is tough.
I've done it, but I'd say that out of 100 shots I doubt I got more than 1 or 2 headshots in.
You'd have to check my stats in the book.
Hmm, can't find it on amazon anymore - annoying.
https://slinging.org/forum/YaBB.pl?num=1468418037/5#5I'll have to find my copy.
I suppose the league number works as a multiplier for the star system.
I like it

Althugh I think you should use 10 shots.
once you get beyond 30 metres, the chances of getting 5 hits in 5 shots is pretty unlikely.
5 hits from 10 shots, is unlikely, but more possible.
And anyone who can get 5 hits at 50 metres out of ten shots - should just get a free t-shirt and plaque.
That's tough.
I have target slung out to 70 metres quite succesfully with a pretty flat trajectory.
But beyond that, I just can't see where the missile is going and at that point you lose the ability to adjust between shots.
If you can see where your missile is going, you can hit a target. If you can't see where the missile lands - and your spotter is rubbish

- then it's just blind luck if you hit anything.
The ultimate difficulty is to throw hard and accurate at distance.