There seems to be a lot of confusion about the genesis of the CETME assault rifle. The story goes like this: Towards the end of WWII, the Germans developed the StG44
Sturmgewehr, which is considered the first true Assault Rifle. It was late in the war and the gun never saw full production. Also under development was the similar StG45, which would become the basis for the CETME. At the war’s conclusion Ludwig Vorgrimler, a german engineer, joined the development team at Centro de Estudios Técnicos de Materiales Especiales (Center for Technical Studies of Special Materials), a Spanish government design and development establishment. Vorgrimler was the primary engineer on the CETME Model A, the first rifle in the family
now known simply as “CETME”. It was first produced in 1957 and was the product of a lengthy development cycle during which Heckler and Koch made numerous inputs. Ultimately H&K developed the G3 assault rifle based closely on the CETME. H&K still produces the G3 and the HK91 semi-auto civilian version.
One of the most interesting features of this rifle is the operating mechanism. Rather than a piston/operating rod (like the AK-47) or direct gas impingement (AR-15), this rifle uses a “roller-delayed blowback” system. What this means is that the rifle has a bolt carrier that locks into the barrel by means of a pair of steel rollers that extend out into recesses in the barrel extension. When the gun is fired the rearward pressure extends through the bolt, pushing back the inner section of the carrier. This allows the rollers to eventually drop out of the recesses and allow the rest of
the carrier to move backward, cycling the action. The delay is enough to allow the bullet to leave the muzzle with full velocity. The design is ingenious and makes for fewer moving parts than others.
There are some drawbacks to the system. First, the gun is heavy due to the added weight of the system. The barrel extension is thick and heavy, as is the bolt carrier. Second, the chamber fluting and massive recoil forces render the brass un-reloadable. For military and LE use, this is irrelevant but for civilian shooters this is a big drawback. The brass is ejected with such force that it easily travels 35-40ft and is imparted with a set of splines that while interesting to look at leaves far too much deformation to try and reload it. Additionally, the gun has a tendency to tear the rims off brass. In fact when I bought mine I discovered there was a broken shell in the chamber!
Speaking of mine, some personal observations are in order. The rifle was a Century Arms International US rifle, made from CETME parts with the requisite number of US components to circumvent the import ban. CAI has a reputation for shoddy guns and this was no exception. The fit/finish was poor but I will say that the gun worked flawlessly during the thousand rounds I put through it. With the efficient muzzle brake it was very controllable under semi-auto fire and once I got good magazines for it it was perfectly reliable. Magazines are common across the CETME and G3 models but some fit better than others. I bought about 20 for $3 each and about 5 of them were not reliable.
The rifle was also fun to shoot but extremely loud. Due to the muzzle brake, this was easily the loudest firearm I’ve ever fired on a range. It got everyone’s attention, especially under rapid fire.
I sold this rifle a few years ago but I expect I will have a PTR91 at some point. If however you are considering a .308 battle rifle, I would be hard pressed to choose this gun over an M1A, especially due to the brass issue.