HK MP5 or HK94 mags origin/vintage query

[msmp5]

Here's one for the H&K Experts.....

I just discovered a few MP5 30 rd 9mm mags in a box that had been stashed away for probably 20+ years, and I am curious about their origin and vintage. Some of them look brand new and are marked MKE. My understanding is that these are Turkish mfg. But I also thought that Turkish MKE MP5 mags had plastic followers; the ones I just found stashed away have steel followers. Did earlier vintage MKE MP5 mags have steel followers, but at some point they switched to making the mags with plastic followers? When? Or...??? I'm also wondering if these (presumably "early") MKE MP5 mags - with the steel followers - are just as reliable as the German HK mags? Anyone have experience shooting these in an MP5 (full auto) or HK94 and can comment on their reliability?

I also found a few MP5 mags simply marked "9mm x 19", with no date codes, no other markings; and they also have steel followers. All of the German HK MP5 mags I have seen in the past had date codes. Did H&K in Germany ever make MP5 mags without date codes on the mag body? Any ideas from the Experts as to origin and vintage on this one? See pic.

 

[unklebuck]

HK MP5 magazines changed from straight to curved about 1977. The difference I found was metal followers were standard and plastic followers were for suppressed rifles. The lips on the magazines with the plastic followers are prone to breaking.