Pretty much most brands of AK mags will fit, but you have to fettle the bottom portion of the rear locking tab. Cyma mid cap works as do cyma drums. With minor work on them.
I mean...they're just plastic shells in retail packaging so they should be OK. The issue isn't so much them being held as possibly being destroyed by Customs. Can you not get them in the UK or are they just that much cheaper from TG?
Thinking about it they may not be that much different. Few other bits I want from there also so that’s why I’m looking. Cheers for input mate. I’ll have a think.