Collapsable HK Stock Build

[schnejerator]

Well I figure NFA thread since... well who else would want to mess with an A2 stock on an HK?

Anyway, I have post SB281 Form 1 for my HK94 and 53 clones. Normally, they would come in at about 26.75 and 28.25 inches respectively when SBR'd with an A2 stock. There are some other solutions with AR receiver extensions, but I wanted something different and not folding (so flash hiders and suppressors are OK). I've only built one so far, for the 94.

And yes, I cut my German A2 apart for this science project. Thanks Frosh!

The design allows pushing down on the spring loaded pin of the side of the stock to release the butt pad to slide in or out. The mechanism itself works pretty well, slides with little resistance. Spring is a bit stiff, but still operable one handed... and this means it is a nice positive lock. Currently I just have it drilled for two locations, full open and full closed.

It still needs some cleanup and final fitting/trimming. More importantly finish the aluminum pieces with a nice, super evil matte black.


Here are the telescoping tubes before trimming:


Test fit of the delrin plunger and spring assembly:


Test fit of the buttplate adapter:


LOP checkout on the HK94 clone (2.5" of extension):


LOP checkout on the HK53 clone (1.0" of extension):


Butt plate fitting around the adapter:


Closed position:


Closed position (again):


Open and locked:


SB281 compliant :

[bm3r]

If that works out this is an amazing idea

[Hawkeye]

That's a fantastic idea, and something similar could really help all the people who'd like to SBR one of the Zenith clones.

[outrider58]

Burning the midnight oil I see. Nice work. Thanks for sharing your alterations with the rest of us. That is really cool!

[smdub]

That is seriously clever! Exceptional job. (from a fellow amateur machinist)

[unshat]

Genius! Funny how much innovation occurs when we are challenged by ignorant laws.

[wbw2123]

Awesome work. That is a great idea. I see many more hk sbr's in MD as a result of your creativity. Thanks for sharing.

[outrider58]

Originally Posted by unshat

Genius! Funny how much innovation occurs when we are challenged by ignorant laws.

Ignorant law- the mother of invention.

[fred333]

I actually posted the second response in this thread, but my computer locked-up just as I hit the Post button. Not sure what happened there, but very clever idea. Good old American ingenuity.

[Sharp]

That idea seems good enough that you could market/sell it!