German military and law enforcement procurement identification of the G1 and G3 CETME are well known, however the question of the G2 often comes up. Here is an incomplete list of of the gewehr models.
G1: FN FAL (Belgium)
G2: SIG SG510 (Switzerland)
G3: H&K HK31 (Germany) licensed from the CETME Modelo B (Spain)
G4: ArmaLite AR10 (USA)
G5: Steyr SSG69 (Austria)
G8: H&K HK21 (Germany)
G11: H&K G11 (Germany)
G21: Mauser Kar98K (Germany)
G22: Accuracy International AWM-F (UK)
G23: Accuracy International AWM (UK)
G24: Accuracy International AW50F (UK)
G28: H&K HK417 DMR (Germany)
G32: Walther KKJ (Germany)
G36: H&K HK50 (Germany)
G37: SIG SG551 (Switzerland)
G82: Barret M107 (USA)
Civilian semi-auto G3, the H&K HK91