With the new system for explosions that just arrived, i recreated these events, and did some more tests, mostly focusing on armor vs shrapnels topic. I didnt even bother doing tests of unarmored human vs grenades etc. since Kevin based this system on real world data of handgrenade lethality vs (i assume) unarmored people, i am not right person to judge anything there.
Lets start with ammo boiling example. Its no longer case of one or few huge damage spikes when 50 9mm ammo explodes 1 tile away, now its about a dozen hits, and each seems to be a little stronger than 9mm shot fired from average gun. It is able do do low damage through light power armor - in normal situation it is immunue to 9mm, and in case of H.S.S. - its a lot of moderate DMG hits, most likely to kill you.
Now lets see how grenades perform. They care about armor even less. At 8 tiles range while wearing heavy survivor suit, you might be lucky to survive explosion, but lethality seems to be above 50%. Light power armor at range of 5 tiles - very high lethality, above 75% (this thing is 36b/36c, about 2,5x times tougher than kevlar vest). Standard power armor is immunue to grenades, even at point blank range, even if you hold active grenade in your hand.
According to my knowledge, these results seem to be off a little at least. I belive that right now damage potential of every shrapnell is based on its kinetical energy, but its armor penetrating potential seem to too high. To penetrate an armor just pure energy isnt enough, the same way like a thrown rock can have same, or more energy than fired 9mm, but that doesnt mean it will penetrate for example - a breastplate better than bullet. To penetrate armor (metal vs metal) first - projectile needs to be sharp enough and hard enough to make a cut in surface, then it needs energy to bent amror material arround to be able to squeeze in.
If its too soft, like copper shrapnell vs tempered steel - it will loose edge and wont be able to cut surface. If it doesnt have enough energy - it wont penetrate either. The same applies to other situations, like adamantium arrow shot from bow at bronze breastplate 2mm thick. Adamantium can be like 100 times harder than bronze, its edge sharper than steel edge can ever be, but if the projectile doesnt have enough energy to bent a hole that is as big as projectile is thick - it wont get through. In this case armor made from soft material can stop something from much better material - only because bending metals, and other materials too reqires tons of energy. And if your projectile, or shrapnel doesnt have nice cutting edge or refined point, or simply is softer than armor material and cant keep its shape during contact - then in order to penetrate armor it needs ENORMOUS ammounts of energy to rip hole in diameter of now squashed projectile.
Now lets look at few historical examples. First “bulletproof” vest ever made, sewn from many layers of silk - so much weaker than kevlar. It was able to stop very weak 8mm revolver bullets. In 1902 it saved Alfonso XIII of Spain from bomb explosion. There arent precise informations about explosion force, we know only that everyone agreed that if not that vest king would be guaranteed death. Now - WWI and steel helmets. Casualty rates dropped by about 15% on fronts where helmets were introduced, and deaths from shrapnels to the head only (excluding hits to face) - dropped almost to zero. And most of these were big mortar shrapnels at very varying ranges of impact. Vietnam - kevlar vest introduced to help aganist grenades shrapnels and not bullets - they did relatively well exactly what were supossed to.
So, in conclusion: In my personal opinion shrapnels should be much worse at getting through armor, not be like bullets fired from rifles. I am aware that everyone isnt going to agree with that, and so far i havent talked about current shrapnels vs naked humans, which i bellive is as realistic as we can get, but, i can see another problem here, and this one unfortunatelly might be MUCH harder to fix than introducking few simple modifiers.
Now lets talk about something that scares me and is very immersion breaking to me - its completely broken scale of range! I will try to explain as best as i can.
It is stated that one tile in game is 1mteter. And explosions are now made extreamly realistic (at least vs unarmored). But EVERY other factor of game isnt scalled to match realistic numbers. This includes movement (characters running at 0,33m/s, while 7,5 m/s is realistic), vision range (about 60-70m of max viev), other weapons effective range and shape of few enviroment features, like cars 4m broad, and walls 1m thick.
Now i am perfectly aware that due to mechanical limitations, we cant have realistic values for everything, like sniping from 2000m with heavy antimaterial rifles, but we can have general scale - like having effective range of sniper rifles 2-3x times longer than standard rifles, rifles having 2x more range than SMG, SMG having 1,5x more range than handguns, handguns having more range than shotguns, and shotguns - having more range than grenade explosion radius. But right now, because only explosives have realistic range valuse, while everything else is not, and often its like 1/10 of realistic value, you can have situation like this:
On open field you meet a bandit armed with m4a1 who has all skills at 4th level. You have 1 skill point in everything, and are armed with mp5 and a grenade. You have no way of defeating a bandit by winning shooting contest, but can simply throw granade 20 tiles in his direction, and if he is 5-10 tiles away, armored or not, he is dead. And he has no chance to engage you at 30 tiles with his rifle and skills. This way 1skil lvl charcter defeats better equipped character on open field only because explosives are OP.
But wait, there is more. Real life grenades have fuse of 6-5 seconds, and killing potential about 15m. It means if grenade lands on you, and you imidietly react by running away, it takes about 2 seconds to get away from 100% death sentence. By this time fuse has probably 2 seconds left, it was abut 4 seconds when it landed nex tto you. Its 1/2 fusetime to get away from death. Now what we have ingame. grenade lands on you, it has 30 seconds fuse, probably 24 when it landed. You can move 2 tiles per 6 seconds. It requires 8x6 seconds, 48 seconds to move 15 tiles. It is 2x times more than fusetime left. You have no chance to escape, while IRL you could have chance to escape. Thats a trap of having only explosives using realistic values, but other factors, like movement - not.