I'm a retired cop (served from the last day of 1973 to 1995 down here in paradise ,south Florida, during the height of the party....) and I have killed on the street when I had to (one shot fired in 22 years.....). I only mention it for some background on my remarks.
I recently decided that I needed a carbine (the original PDW) for the exact purpose it was originally designed for -as a personal defense weapon for my vehicle (I have a different weapon for home defense purposes). I know that the original military "hardball" ammo means great penetration - but could probably be improved upon in the civilian world. I remembered reading that a NYPD stakeout team had great results using softpoint ammo working robbery details in the late sixties.... That was specifically why I chose a carbine (the other two "possibles" were a mini 30 tactical from Ruger or an S&W sport 15 in .223 -but the carbine was just much more interesting..). I'm also a Vietnam vet (although only a pencil pusher back in 1971) and I did remember that many of the ARVNs were equipped with carbines as well...
So with all that in mind I recently purchased an old carbine in nearly new condition (not a USGI -in today's world they're out of my range). It was a Plainfield and appears to have come from the early seventies -towards the end of their production time. Haven't been to the range with it yet so that we can get acquainted. When I do it will be with hardball to verify aim, function, reliability then finally with softpoints to make sure it feeds them properly and that I can go through a box without an jams, failures to fire, etc.
Once it passes it will go into service - and I'll be pretty confident that it will be exactly what I want - something quick and maneuverable with a bit more power than .357 for the possibility that it might one day really be needed. I've read a lot of accounts about the performance issues in the Korean conflict and I can understand that concern. I also know that many cartridges don't perform up to spec in extreme cold weather (not a concern in my world).... Unfortunately, down here... if I ever need a weapon away from home I'll probably be facing more than one opponent - just what that little carbine was intended for....