Could he? Wizards are apparently able to handle significantly more physical trauma than Muggles and have access to considerably more advanced medicine.

Like, they teach 11 year olds to play sports on flying brooms several stories in the air in which they hit heavy balls at each other very fast. They teach 16 year olds to teleport with the explicit risk that they might mess up and leave part of themself behind (and we don't even ask the question of what happens if there's something physically blocking their target location, such as another person). Somehow, the school doing these things doesn't have multiple fatalities every year which means that getting hit then falling 60 feet to the ground is generally not a death sentence, or even a particularly serious injury.

You shoot Voldemort pre-horcruxes and he's likely going to apparate away, drink a healing concoction of some variety, and try again in a few hours or days unless it's a headshot. You shoot him post-horcrux, and even if it is a headshot that's just a somewhat longer delay. And that presumes a lack of some kind of magical defense that would block a small projectile coming at you very fast.