GURPS And Underpowered Ammo

Shooting the bad buys with inadequate rounds.

The average Joe Mook is a 10 HT, 10 HP schmoe.

A .25 ACP round fired from a pocket pistol does a whopping 1d pi-.  Anything what penetrates the DR gets halved.

Shooting someone in the torso deals a minimum of 1, a maximum of 3 and an average of 1.

Getting them in the vitals does a minimum of 3, a maximum of 18 and an average of 10.

Getting them in the skull adds DR2 to the Mook and makes the minimum damage 0, maximum 16 and average 6.  Plus there's an extra consciousness roll for the head shot.
Going for the eye bypasses the skull DR making the minimum 4, maximum 24 and average 14.

Shot placement is everything!  Also, on average, you're going to need more than one shot to kill someone.

.22LR from most any pistol does 1d+1 pi-.

On the body that's minimum 1, average 2 and maximum 3.
On the vitals it becomes minimum 6, average 13 and maximum 21.
Against the skull it's minimum 0, average 10 and maximum 20.
The eye yields minimum 8, average 18 and maximum 28.

.22LR from most any rifle does 1d+2 pi-.

On the body that's minimum 1, average 2 and maximum 4.
On the vitals it becomes minimum 9, average 16 and maximum 24.
Against the skull it's minimum 4, average 14 and maximum 24.
The eye yields minimum 12, average 22 and maximum 32.

All three rounds against something important, like the vital organs or brain, are more than capable of rendering the Mook unconscious by delivering the requisite 10 points of damage, and occasionally getting a death roll by doing 20 or more points.

Under no circumstances should any of these rounds be considered enough medicine for a T-Rex.  Unless you're very patient, brought lots of ammo and have a very secure firing position.