The stamp indicates the range of case thickness.
It indicates the brand, there may be variations in manufacturing equipment as well but there are references to wall thickness from various manufacturers.
Neck thickness data:
Factory Blackout brass
Gemtech (factory 300 BLK) - 0.011"
PNW Arms - 0.011"
RP - 0.010"
Good:
ADI - 0.012"
Aguila - 0.012"
A USA - 0.012"
FC - 0.013/0.014" [Note 1]
GFL - 0.012" (Fiocchi) Some GFL may have different thickness
HB - 0.013"
Hornady (223 headstamp) - 0.011"
Hornady (nickel 223) - 0.012"
IK03 - 0.012" [Note 4]
IMI - 0.012" [Note 4] Listed on both lists, but seems like more often good than bad.
IVI - 0.013"
IVI ('85) - 0.012" (runs great)
LC - 0.011"
LC (converted blank) - 0.012"
M193 - 0.011/0.012"
Norinco 223 - 0.010"
NOSLER - 0.012”
PERFECTA 223 rem. - 0.012"
PMC - modern "bronze" and "X-tac" are good, older PMC with small letters may have problems
PS - 0.011/0.012"
PSD - 0.011"
RA - 0.013"
RA ('69) - 0.012"
RP .223 - 0.011"
SSA - 0.012"
TAA - 0.013-0.014" [Note 4]
Tula - 0.0115"
TW 67 - 0.012”
TZZ - 0.012"
WCC - 0.010/0.011" (Some less common WCC headstamps run thicker, but the majority are good to go)
Winchester - 0.011"
WIN NT - 0.011"
WMA 15 - 0.011"
Thick neck wall, bad without neck turning:
AB 556 - .015" to .016"
ATI - 0.015" [Note 3]
CBC - 0.014/0.015"
CJ6 - 0.015"
CJ 8 - .014"
DNL - 0.016"
FNM - 0.016" [Note 3]
FRONTIER - 0.015"
GECO - 0.015/0.016"
Hot Shot - 0.014" [Note 3]
HRTRS ( Herters?) - 0.017"
ICC - Reported as bad
IK03 - 0.015" [Note 4]
IMI - 0.015" [Note 4]
IVI - 0.015"
KFA .223 REM - 0.015"-0.019"
L2A2 - Reported as bad
MKE13 - Anecdotally reported as troublesome
MPA - 0.015"
Norma - 0.015"
NPA - [Note 3]
PMC (old headstamp) - 0.015"
PMP - 0.015"
PPU - 0.014/0.015" [Note 3]
RAM 223 - .014"
RORG - 0.015"
RWS - 0.014-0.015"
S&B - 0.015/0.017"
SADU - 0.014/0.015”
TAA - 0.013-0.014" [Note 4]
SADU 5.56 - 0.014-0.015"
Wolf Brass .223 - 0.014"
The case head doesn’t matter other than identification of the mfg. what matters is the wall thickness once you chop the case down and form it.
You can either chop it down form it and measure or build something like this that allows you to measure wall thickness inside the case first.