Mindflayer wrote:I welcome any of you to stand downrange and take 5 rounds of 9mm. We'll give you a month to get better, then take 5 rounds of 5.56 NATO. Both of these are considered to be calibers incapable of stopping a man. We'll give you a month to get better, then 5 rounds of .45 ACP. Please report.
This is asinine and illogical. Purposefully getting shot with anything, even a .22LR, is a bad idea and potentially deadly. That doesn't mean .22LR is a good SD caliber.
Personally, I think 9mm and 5.56mm are both good defensive rounds with the proper ammo. With proper ammo all of the common defense calibers perform very similar. Where they differ is barrier capabilities and failure modes. Specifically:
1. Bonded bullets trade some expansion for barrier penetration. Barriers can be interior walls/studs, car doors/windshields, light equipment (think mags, LBE, potentially heavy clothing, etc.), etc. Most people consider this a good trade off, but there are lots of LEA who use Ranger Ts which are not bonded, so it obviously isn't a consensus agreement.
2. Larger bullets tend to have less severe HP clogging failure modes. I.e. a cloged .45 is still .45 while a clogged 9mm is "only" .355. Personally, I think bullet shape of a clogged HP is more important than 1/10th of an inch. I.e. truncated cone designs and other flat/non-rounded profiles tend to crush tissue regardless of expansion. The tradeoff is that larger/slower bullets like .45 tend to be more prone to clogging. A proper risk analysis (probability of occurring vs. impact) would equate the risk to more or less equal IMHO.
IMHO, military 5.56mm (M855) is very effective when it works, but if it doesn't fragment early due to fleet yaw issues then its failure mode is very bad. The issue is that the failure mode is very bad and the probability of occurring is relatively high when shot out of M4s. Tactical LE and hunting 5.56 rounds solved this a long time ago.