I'll keep it simple:
1) Are they available as midcaps for any of the common brands? (Ares, etc)
2) Has anyone done a conversion / custom build for them? (similar to the Stg.44 high-to-mid-cap conversion)
My thoughts have been along the line of #2, with the idea of using something like an MP5 midcap as donor / base mag to work from. Ideas and suggestions are welcome.
No mate the mags are 500+ round hicaps both for the ares and the s&t (which is copy of ares anyway)
Have two myself that i would love to know whether a mag conversion like you asked would work for but hopefully some one a bit more technical would answer that for you.
Here is what I had in mind:
Now, to my eye, those two mags look pretty damn close. I do not have the gun or magazine on hand to test the dimensions, but it seems like one would just need some kind of fitted jacket/sleeve around the top of the MP5 mag to get it to fit into the larger PPSh magazine well.
On a related note: for German units that were issued the PPSh - in either MP41(r) or MP717(r) form - what ammo pouches were used for the spare mags? I am wondering now whether they would have used captured Soviet ammo pouches as well (looks as if they would fit perfectly on the German webbing):
- stick mag pouch: http://hikishop.com/ww2-soviet-red-army ... -1044.html
- drum mag pouch: http://hikishop.com/ww2-russian-red-arm ... -1046.html
EDIT: never mind, my Google Fu decided to switch on later...
http://www.redwolfairsoft.com/redwolf/a ... gazine.htm
It says that the magazine is metal - so I assume one can open it up and remove the plastic high-cap internals? If yes, then the option of mounting a plastic mid-cap MP5 or MP7 magazine inside should not be completely impossible.
EDIT 2:
This is what you would need - a metal MP5 mid-cap mag:
http://airsoft.tiger111hk.com/p16225/CY ... _info.html
Take the plastic midcap internals out of the MP5 mag, fit it to the metal shell of the PPSh mag, and dremel away any obstructing bits. Finish it off with a simple retaining pin somewhere to keep the internals in place relative to the shell.
I made one for my Hexagon through a real one and a long MP7-magazine, so it should be entirely possible 
Takes an awful lot of dremeling to make it go in properly (remember that it narrows a lot at the top), but well worth it 
Any reason you used the plastic MP7 mag over a Cyma plastic-in-metal MP5 mag? Expedience maybe?
My S&T PPSh has been ordered, will get mags as well and report back. I think it is time for an Waffen-SS Ostfront veteran look, yarr...
The hexagon feeds from the back of the magazine, unlike most aegs, so I only found the the MP7 and it's sister the vz61 to be viable at all 
There might be MP7-mags with a removable sleeve too, but I just spoke to a Mp7-gunner and managed to trade one for an AK-sling.
As for MP5-mags, they actually curve a bit more. but are for a shorter round as well, so its hopefully workable!
P.S. Just judging by your links, schuster.ru actually does much nicer soviet reproductions for mostly similar prices
Okay, that makes sense. The S&T and Cyma MP5 are both front feeding, hence my suggestion there.
