Also consider high velocity (barely supersonic) or hypervelocity (fairly supersonic) .22 LR ammo, fired at 100 yards. It starts out supersonic, but it is well subsonic at 100 yards. It'll likely shoot like crap at that distance (at least it always has every time that I've tried!), but the bullet holes will be round.
W.r.t. rocket scientists, don't pay them too much heed, they're a dime a dozen really.... ;-)
If you read "Hatcher's Notebook" (highly recommended!), he did some interesting experiments firing a .30-06 machine gun (1-10" twist) vertically into the air.
When he used 150 grain flat base ammo, the bullets were so overstabilized that they returned to earth still pointing nose-up.
When they fired 173 grain FMJBT ammo, the bullets were stable but not nearly so overstabilized. At the peak of their trajectory (~10,000') some would tumble and some would not. So the bullets returned in two batches - first, the boattail-down ones, followed by the tumbling ones. (the still-stable boattail-down ones had less drag than the tumbling ones, so they got back sooner).
Berger recently hired as their chief ballistician Brian Litz, who is a pretty sharp cookie (and rocket scientist to boot). He also shoots a Palma rifle quite well.