I watched the Forgotten Weapons Gerat06 video again the other day, and I started thinking about that rod sticking out from the bolt carrier. How come the CETME and HK rifles have the rod on top and pointing forwards, instead of rearwards? I don't think they would have had a problem fitting a recoil spring behind the bolt carrier group either way.
http://s33.postimg.org/7zaibaljj/RDBB.jpg Do you think it could have anything to do with the fact that they really wanted that charging handle manual of arms? By putting the rod forwards, you get this nice cylindrical channel where you can put your charging handle, which makes your big rifle works just like the submachinegun you're already used to. I like this explanation, because it seems reasonable that a design to replace the obsolete bolt action rifles to work alongside not-yet-obsolete 9 mm submachineguns would be designed to have ergonomics matching the submachineguns, to reduce training time for ww3. If I'm not mistaken, quite a few WW2 era SMG's are reloaded by 1) locking bolt open manually 2) inserting magazine 3) letting bolt forward. The G3 is reloaded the same way. Note that this is one more operation than for example an m1 thompson, m1 carbine, stg 44, ak or other no bolt hold open firearms with detachable magazines. I haven't tried but I don't think you're supposed to load a G3 with the bolt closed. Correct me if I'm wrong.
On the other hand, it seems weird that they would value quick and easy reloads so lowly that they didn't just ditch the old manual of arms and made their rifle easier to manipulate (adding, for example, a bolt hold open, which would go well with magazines that are really hard to insert when fully loaded). That rifle could have a 9 mm SMG to go with it, using the same simple manual of arms. Unless there's some benefit with the extra weight of the taller receiver and charging handle assembly, the design of the CETME/g3 seems a little weird, considering where it came from.