Shotgun Acronyms/Abbreviations

Here are some of the commonly used shotgun abbreviations:

LOP – Length Of Pull, is the distance between the front face of the trigger and end of the butt plate or butt pad.
CQB – Close Quarter Battle
CQC – Close Quarter Combat
SD – Self Defense
Cyl. – Cylinder
IMP CYL – Improved Cylinder
VCS – Vang Comp Systems, http://www.vangcomp.com

Do you know any other abbreviations? Please leave them in comments.