Oops. misspelled ammo.
A large gaping wound caused by a hollow point bullet isn't the goal. A hit is - and the bullet has to pass thru cover often as not to get a hit. Full metal jacket does that, HP flattens out with half the penetration - or less.
As for open tip ammo use, that dates back to the 1980's when JAG studied the issue and declared bullets designed for aerodynamic stability weren't designed for maximum expansion, if at all. The intent was to jacket the core from the base to tip, leaving the nose lighter for stability. And it had been working since 1954 when the Matchking took Olympic Gold. Since that was the world standard long distance bullet and it wasn't considered a "dum dum" then we could use it. And that opened the legal door for our snipers to do so. It's been done for decades, the Mk 262 in 5.56 is a 70grn OTM meant for SPR use and also highly preferred by MK18 SBR shooters.
Here's the point - for personal protection or LEO use, the intent of HP bullets is to stop someone and the sooner the better. You don't want to have to shoot them repeatedly. In war, the use of FMJ or steel penetrator ammo is to get to the target. Since a lot of it is high density gunfire someone will likely get hit more than once. A thru and thru is a hit - and hits create difficulty with the soldier continuing the fight. He isn't fully capable of returning fire, it's much harder to manuever, and with more soldiers hit, the unit is less capable of returning fire or holding ground.
Pollce on a crowded urban sidewalk isn't soldiers in defensive positions with mortar and artillery support. Two completely different situations - the first has a goal of ZERO collateral casualties, the second enhances and improves them. And in combat, a lot of soldiers are hit by rounds never aimed at them. The high volume and their continued movements to gain tactical fire superiority put them into a line of fire they didn't even know existed.
Take a look at what the FBI are testing for - 12 to 18 inches of penetration, and the major obstacles are denim, t shirts, auto glass and thin sheet metal. Take those FBI approved rounds and then try shooting solid core wood office doors, sandbags, logs, body armor, two AK mags in series fully loaded, etc. HP performs poorly at those, FMJ is better, steel cored penetrator rounds beat them both, and armor piercing? It's a known fact it bounces around inside helmets, motor vehicles, and small confined masonry buildings to produce multiple hits. That isn't something we need when arresting a mentally unstable homeless man on a public street - and why its not legal to possess in some jurisdictions either. A few people misused it and that's why we can't have nice things.
Just like there are differences between handguns and rifles, there are differences in what kind of bullet and why it's purposefully chosen for the job.
