[untrained skeptic]

"Maybe he used the ubiquitous, yet underpowered Makarov pistol? Perhaps he should have used Corbon ammo rather than FMJ?"

Makarovs aren't underpowered with proper shot placement, and with a suicide proper shot placement shouldn't be a problem.

If the normally free-floating firing pin on a Makarov wasn't floating freely due to improper maintence, it's possible that the gun would slam fire after the first shot and empty it's magazine in full auto fashion.

In that case it's possible that only the first two rounds made contact before the recoil caused the remaining rounds to miss.

We don't know what the weapon was, but it it was a full auto or burst fire weapon, then multiple head shots make more sense.

[FreedomCalls]

See my number 34.

[jb6]

First bullet under the chin, second in the temple.

[donozark]

Few weapons are underpowered with proper shot-placement. But 9X18MM is considered by most, to be underpowered.