Так ссылки на авторитетные источники и испытания будут? Похоже, что вам самому придётся гуглить отличия затворных групп у CETME Ameli и MG42.
Я думаю ответа от вас ждать бесполезно, поэтому напишу сам: "пулемет" CETME, это не более чем развитие MG 42 (G3):
"Roller-delayed
A schematic of the roller-delayed blowback mechanism used in the MP5 submachine gun. This system had its origins in the late-war StG 45(M) assault rifle prototype.
Roller-delayed blowback was first used in Mauser's Gerät 06H prototype. Roller-delayed blowback operation differs from roller-locked recoil operation as seen in the MG 42 and gas operated roller locked, as seen in the Gerät 06[14]. Unlike the MG 42, in roller-delayed blowback the barrel is fixed and does not recoil, and unlike the Gerat 06, roller-delayed blowback systems lack a gas piston. As the bolt head is driven rearward, rollers on the sides of the bolt are driven inward against a tapered bolt carrier extension. This forces the bolt carrier rearward at a much greater velocity and delays movement of the bolt head. The primary advantage of roller-delayed blowback is the simplicity of the design compared to gas or recoil operation.[15]
After World War II, former Mauser technicians Ludwig Vorgrimler and Theodor Löffler perfected this mechanism between 1946 and 1950 while working for the French small arms manufacturer Centre d'Etudes et d'Armament de Mulhouse (CEAM). The first full-scale production rifle to utilize roller-delay was the Spanish CETME, which was closely followed by the Swiss SIG SG 510 and the CETME-based Heckler & Koch G3. Heckler & Koch's MP5 submachine gun is the most common weapon still in service worldwide using this system. The Heckler & Koch P9 pistol also uses roller-delayed blowback."
https://en.wikipedia.org/wiki/Blowback_(firearms)
