I started out the same as you and just maybe I can save you a little frustration. The following has been my experience. It is a whole new ball game you are playing…..
The TC Hawkin is a good gun to start with, i love my renegade but it's no good for precision at more than 100 yds. But, to be fair I have never seriously tried.
As others have said before me, round ball is best considered a short range, by your standards, projectile.
.After about 100 yds they tend to wander off, and develop a trajectory like a golf ball.
I play a guitar and thought I could change over to a banjo easily. I did it, and my previous experience with strings helped a lot because I knew what I was trying to do, but it was not as easy as I thought it would be.
Persist and you'll get where you wanna go.
It's all good fun mate