The ZB26 & 30 are supposed to be chambered in 8mm Mauser, (and I understand compatible with the FG42) however the airsoft ZB26 mag I have appears to be chambered/scaled on a .308 round (L4A1 magazine?)
The magazine is ~90mm long (externally) and removing the magazine follower (part at the rear) leaves ~80mm (externally) for the double stacked cartridges.
An 8mm Mauser round is 82mm long, while a .303 british is 78mm and a .308/7.62 is 71mm long (according to wikipedia).
Last time I checked 82 > 80, so it would be impossible to fit Mauser rounds (and pretty tight for a single .303, let alone staggered rims) into this AEG magazine. 
I understand a BREN magazine is ~95mm long and, by interpolation, a FG42 or G43 mag would be around 105mm.
As a final check the aeg ZB mag fits in a FG bandoleer like a bicycle in an airplane hanger.
Can anyone confirm that the airsoft ZB26/30 mags are undersized?
depends which model you get
IIRC the rock (and i believe the a&k) brand zb's use m14 mags (so undersized) where as the china clone zb's (all the rebrands matrix,echo1 ect ect) use an actual size zb mag
i believe when they were first announced everyone was a bit confused as to why they would go to all the work of releasing a new gun but messing up the mag size
also the matrix ones(correct mag size) are available from evike atm for $250 picked one up myself, a decent saving (in the UK at least) even with international shipping and customs fees
The Matrix mag I purchased from Evike measures as undersized.
Most airsoft guns mags are different sizes so dont get to hung up guys. Its still a great looking gun!
Have you ever seen a real steel m1 carbine mag compared to ANY of the airsoft ones. They are at least 3 times bigger!
Stu
