would someone please tell me where I can find a list of all the acronyms and what they stand for as it relates to an ar15 or m4
Not sure there is one, but this question has been asked before. I’ll list what I can thinkof to get you started. Hopefully others will add on.
FSB = Front Sight Base
BCG = Bolt Carier Group
FCG = Fire Control Group
RDS = Red Dot Sight
HBAR = Heavy Barrel
LR = Lower Receiver
UR = Upper Receiver
QD = Quick Disconnect
Here’s some from gotM4 on another thread:
LMT = Lewis Machine & Tool
CH = charging handle
RRA = Rock River Arms
SOPMOD = Special Operations Peculiar Modification
SOCOM = Special Operations Command
NFA = National Firearms Act
ATF = Alcohol Tobacco and Firearms (also BATFE, Bureau of Alcohol Tobacco Firearms and Explosives)
SPR = special purpose rifle
DMR = designated marksman rifle (USMC)
SAMR = Squad Advanced Marksman Rifle (USMC)
GB = gas block
MPI = magnetic particle inspected
FS = flash suppressor (i.e. A2 ‘compensator’, i.e. ‘birdcage’)
BUIS = back up instant sight
COWITNESS = meaning you can see the reticle and irons at the same time (there is absolute cowitness, and typically lower 1/3 cowitness most people prefer the 1/3)
HC = hard chrome
RE = receiver extension (aka buffer tube)
POA/POI = point of aim, point of impact
FDE = flat dark earth (a shade of the color brown)
CB = chrome bore or coyote brown
OD = olive drab
FG = foliage green
CQB = close quarters battle
CS = chrome silicon
BCM = Bravo Company Manufacturing
MIAD = Magpuls pistol grip stands for Mission Adaptable Grip
CTR = Magpuls ‘compact type restricted’ stock
UBR = Magpuls ‘utility battle rifle’ stock
PRS = Magpuls ‘precision rifle/sniper’ stock
PMAG = Magpuls polymer magazine
thank you that helped me out alot
Note that “87” is still on the list of acronyms over on ARF. 
I’ve always taken BUIS to mean Back Up Iron Sight.