Ammo with PS subname

[AncientSion]

For most of my convential guns i can produce two types of ammo. One being "normal", the other with the suffix "PS". I thought its means to be Poison-Type ammo, but is that actually the case ? The Bootypedia, for the hunting rifle, just indicates this PS ammo has a slightly higher power yield 40 for PS ammo versus 33 for stock ammo ?

[Meridian]

PS stands for Plastasteel.

[AncientSion]

Ack. Thanks