Golf ball size. It's not difficult. Light pellets with poor aerodynamics are not going to perform well at a distance. Not great with little power behind them, arguably worse with a huge hoof up the arse.
Scopes are not necessary for ranges where pellets are effective. If it gives you a warm feeling in the mudbox, fill your boots. It's not something I'd bother with in the bush and of little use to me on a range. If you can't see your target properly with the naked eye, there's little chance of hitting it with low powered light projectiles.
More than one contradiction in there mate but to be honest, you clearly have the blinkers on so I shan't bother.
My advice to you would be to learn more about air rifles and the nature of pellet trajectory etc.