the point of a round nose, or even better a blunt nose, is to crush instead of poke. a 30-30 isn't going really fast OR heavy, but it's got enough of both to do the job. you place your shot right, use a bullet that will crush instead of poke, and you have a hole in vitals that stays open and is 1/3 of an inch. can a spitzer do that at slower velocity, yes, but not likely (little holes seal up). can a 30-30 open up at slower velocity, yes, but not likely very well and it won't be going fast enough to get through much meat if it DOES open up wide.
consider energy dump within 100yds. do you want the bullet to get caught in the deer and give him a good jolt, or do you want to poke a hole in him reliably? hydrostatic shock wouldn't be terribly impressive at a distance with a light bullet, but a heavier one with a good MEPLAT would give your target/deer some.... would it get deep enough to shock the vitals though? a big wound cavity on one side is good, a big wound cavity inside is better. You research it enough to make sure your bullet can get inside before that blunt tip stops and you're good.
I took that concept a bit too far this season, smashed a deer in one side and up into the armpit of another. catastrophic damage in a relatively narrow wound channel. there was hydrostatic shock galore, but it only radiated out 2 inches, and the bullet was a 300grain .458 hp. a 30-30 would be lighter but longer and have better sectional density to keep pushing, less meplat means less resistance, less mass means less inertia to keep it going though. it kind of balances out. less recoil for 30-30, still kills deer. Mine stiffly walked/trotted about 50yds away after I shot him, looking around the whole time, looking for bedding and cover. I felt bad and panicky, like I failed horribly. Once I butchered him I could see he had no chance of living from that shot due to being smashed up so bad but he STILL suffered, had to after moving so far before collapsing. He suffered less than animals that get butchered and sold to market though, and that hasn't stopped anyone I know from eating meat. I think you're good- just keep in mind what particular ammo and shot combination your circumstances are hunt to hunt. Deer die of disease and starvation too, and getting slapped/tagged by vehicles, so guilty conscience aside, it was gonna feel some pain one way or another. I'm sorry you had to feel that, you're wiser for it now though.
