Nope. Been there, Done that.
Paintballs drop like Rocks. Line of sight aiming devices are good ONLY for the distance they are zeroed in at. Say 25 yards is the zero.
You will be 6 Inches high at 20 yards and 8 inches low at 30 yards. Mostly a MISS for a head shot.
Otherwise, they Guy you are shooting at NEVER seems to be at the distance you are zeroed in at.
The possible exception is to use a line of sight aiming device Like a Red Dot or scope with a Flatline or Apex, etc. barrel that puts backspin on a paintball so it flies more or less in a straight line for about 30 yards.
I'm assuming you have a sight rail with an angled fed hopper like a Tippman.
What you want is to build yourself an Auto Rangefinder sighting system that gets the elevation right for any distance 20-50 yards for a head shot. How I got named Head Hunter. It worked....
TWO limitations you will have to live with. The sighting system is MORE accurate than your marker or paint.
Paintballs are NOT that round NOR accurate for a 50 yard shot. Might have a 24 inch ball pattern at 50 yards making the ODDS of a head shot maybe 1 in 4 rounds fired. But with a Burst Mode or Full Auto those odds are about 1 to 1 you will get a break before he can duck...
The rangefinder is muzzle velocity critical. 10 fps variance from one shot to the next is acceptable. 5 fps is great for field paint. More than that will be limiting.
A Faster ball shoots higher than the slower ball. At 50 yards 10 fps is a FOOT difference - a miss
So to maximize its potential, you will have to clean and maintain your marker in pristine condition for every game. If allowed, you want to use tournament level Premium Paint that is round and accurate.
Be warned, there are a lot of boxes label 'Premium' and 'Tournament Grade' that ISN'T. So ask around about paint quality. Most scenario games make you use their field paint anyway.
Anybody can build an autorangefinder with simple shop tools. Anybody Interested?
Send me a private E mail so I can reply with the attached pictures and How To files. firstname.lastname@example.org