Baby ball pythons are known to strike more often, most likely out of instinct seeing you as a predatory threat. If a BP tags you it usually just feels like pricks from hypodermic needles. Cat and dog bites hurt worse, unless for some reason the snake latches on and doesn't want to let go, which I haven't seen happen very often. Also, if the BP hasn't been handled much at all it is more likely to strike out of fear. My male "rescue" came to me already four years old but hadn't been handled in at least two years, not exaggerating. He tagged me the first night I brought him home and would strike any time I opened his tub. Since getting him, he's completely calmed down and never strikes at me. So it also depends on the temperament of the individual snake and how comfortable it is being handled.

20 gallon long might be a bit big for a hatchling size Ball Python, but I'm not exactly sure because I use tubs and all of my Ball Pythons came to me either fully grown or almost fully grown.