So true! That cracked me up!According to your research, is there a significant difference in terminal ballistics between a .308, 7.62x39, and 5.56x45 at across-the-room distances? The US Army already found that answer to be "no" regarding common military ammo, so I would be curious to see if your findings differ.
The permanent wound cavities created by FMJ 5.56x45s are generally bigger than those by FMJ .308s at close distances, with FMJ .308s creating bigger permanent cavities at distances past the effective range of the 5.56x45. Of the three, the 7.62x39 has the smallest permanent wound cavity across all distances.
However, since you and I aren't limited to JAG-approved ammo to protect our homes with, this obviously expands our options to hollow point and soft point bullets. With these options now available, there is an increase in nearly all rounds' terminal effectiveness. Keep in mind that external ballistics, muzzle control, muzzle flash/report, and weapon size and weight all factor how suitable a given caliber will be to home defense. Cops and soldiers would be armed pretty differently if they were solely concerned with terminal ballistics.