I would like to share some info regarding the so called 'large capacity' 7.62x51 CETME mags.
I got a couple of CETME magazines sold as 30 rounders. It did surprise me that the 30 rounders were taking only 26 rounds each but never gave it a second thought.
Then I found what the seller was calling a 25 round magazine, which was slighter shorter that the so called 30 rounder but definitely larger than the standard 20 rounders. When I loaded that 25 rounder I only could get 20 rounds on it!!!
So I went to my reference books and started to look for info on those 'large capacity' magazines.
It seems that those mags were originally made for the CETME Model A-2 in 7.62x51 CETME-NATO (basically a underpowered 7.62 NATO round) and were actually meant to be a 20 rds and the larger a 25 rds capacity mags.
Cetmes A-2 in 7.62x51 with 25 and 20 rds mags.
Both magazines fit and function perfectly on the later Models B and C CETMEs.
So, is there or ever was a real CETME 30 round magazine?
The answer is YES. The Model A-1 in 7.92x40 and 7.62x40 had a banana shaped 30 rounder:
The CETME family: Models A-1 w/ 32rds mag, A-2 with 25rds mag, B with 20rds old style mag, C and E with synthetic 20rds mag:
Here the picture of the whole 7.62x51 collection: A-2 25 rounder, A-2 20 rounder, B&C 20 rounder and 5 rounder.
Some pictures that will explain why is so big the differences in size of both 20 rds magazines, the older A1 and the later B & C:
Note how different the construction is and the incredible high follower with something that I will call the 'anti-tilt stabilizers'. Shown 20 rds B&C, 20 rds A1 and 25 rds A1.
The two 20 rounders followers and springs side by side:
Some people claim they can fit 22 or even 23 rounds in the A1 20 rds mag and up to 27 or 28 on the A1 25 rounder. That is very likely to happen if you cut the 'excess' of the 'anti-tilt stabilizer':