I have taken an Hk93 clone in trade and it came with 2 stocks, the standard stock and a
collapsible stock. How do you tell if the collapsible stock is h&k or not?

Concave

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looks like an mp5 F style stock or clone

is there a cut out on the left fork?

can you get a pic inside the backplate? and maybe of the buffer?  

I will get a few more pics up in a few.

If you look at the shadow on the laptop........... It looks like there is a cut out on the left fork.

HK makes an F stock with the cutout for the 40/10 and they call it the "MP5 Universal Stock" so if a dealer orders one and does not specify 9mm they will receive the Universal.

That fact aside...

The stock pictured is absolutely, unquestionably the ATI stock. HK does not use paint that glossy on the backplate and the separation of the backplate plastic from the steel is typical of that stock. There is nothing wrong with the stock, ATI makes a solid stock.

It is worth $90-$110 used. About $125-$135 new. The HK version of the stock is about $500.