Just for the record [don't take this as my statement of supporting the selection]:

A more or less official statement sadi that the Haenel weapon fulfilled all requirements and was "over the expected lifespan" cheaper than the competition.

The 52 million EUR figure cited in this thread does not show up in any official statement I am aware of. I have no idea how close it is to the truth. 

I guess this channel will be interesting for you:

https://www.youtube.com/channel/UC6htLMymL0WJSNe109iBU1A

grand-grand-grandfathers of pocket knifes aka navajas

I'm trying to fully understand the role of a replaceable cam in extending rifle's lifespan

Would you be (or anybody) be so kindly to develop it?

An AR-15 does not have APE which means the interior of the aluminum receiver stops the bolt from locking prematurely. Over time the wall of the receiver at the cam pin location wears out and the upper has to be replaced.

The wears could also be minimized by using a roller cam pin. Then again it's patented stuff so companies don't go around making one.

Wonder why E. Stoner made the cam pin rectangular instead of smooth rounding in the first place.

The roller isn't in patent. There are Armalite guns from 1960 with roller cam pins.

It's ultimately unnecessary and adds cost, which is probably what they were thinking at the time (would have been Sullivan and Fremont). However I agree a roller is an improvement. My guns avoid this issue entirely by using an APE rod.

The APE rod is ideally the best way to go yeah

I apologize in advance but... would an up-scaled 50 BMG variant use a Great Ape rod?

There's no reason it couldn't.

nincomp said:

I apologize in advance but... would an up-scaled 50 BMG variant use a Great Ape rod?

Are you trying to make a monkey out of us?