Thanks to all for the wide variety of opinions. Suitably motivated I did some more extensive research for myself & discovered:
a: The rod is a fixed part of the plug, not in any way a seperate component.
b: There is no "gas adjustment" for the mp43/StG44 that I can find any record of anywhere.
c: the gas piston/bolt carrier & bolt are removed from the rear, it is not possible to remove the "gas piston" from the front as it is too deep where it engages the bolt.
d: This little tidbit on "cruffler.com"
“The Maschinenpistole 43 (MP43) prototype was developed in the final months of 1942 and was an evolution of the MKb 42(H). Improvements included a change to a closed bolt firing system. This necessitated the replacement of the striker firing system to one with an internal hammer. The gas cylinder tube was simplified, and a new stacking pin formed the upper part of the gas plug.”
Thanks for all the input folks.
Allan Quatermain: “Automatic rifles. Who in God's name has automatic rifles”?
Elderly Hunter: “That's dashed unsporting. Probably Belgium.”