First time MP5k owner here, but long time AR-15 owner. I got myself a DJ Getz clone of an MP5K.  I added an American-made vertical grip forend, and Choate folding stock.  I gotta say the amount of wobble on both the forend and buttstock were more than I expected.  Certainly more than any AR-15 I've handled.  I can see that the design doesn't exactly do it any favors, so I'm not criticizing Getz.

I'm curious to know if there are any popular improvements for either?  I can see adding a bolt and nut to the forend instead of the push-pin.  Not sure what to do about the buttstock.

Any insight would be appreciated.  And this is more of an information-gathering question. I'm not trying to shit on either Getz or the MP5 design.

Thanks

Replace the Choate folder with a B&T folder

http://www.hkparts.net/shop/pc/MP5-94-UMP-Style-B-T-Folding-Stock-p16928.htm

The American made stuff often doesn't fit properly.  Source a German foregrip.  Not sure about the stock...my German a3 stock installed perfectly to my Getz DJ89

B&T stocks lock up solid and seem to be a snug fit on DJ Getz clones. Only wobble I have experienced is the lower housing moving up and down some. I guess this is in part due to the lack of a front pin and the way the end cap is the only thing holding the housing to the receiver by design.

Mine is just the opposite.  On my IGF MP5K the vert grip and Choate stock go on extremely tight, making it nearly impossible to push out the pins by hand.  Need to lighty tap them out with a punch.  Of course I'd choose too tight over having wobble.  I'm using an HK vert grip btw.

The Choate side folder does have a tiny bit of play in it though, but that is inherent to the locking mechanism.  Where it mates to the receiver is rock solid.

Something I noticed long ago about the Choate stocks is that the HK marked stocks have the Choate folder that is cut and attached to an original HK endcap while the Choate marked and marketed stock has a one piece attachment point.  I'm guessing that HK was less than impressed with Choate's ability to produce a good fit to the receiver so they specified the stock to use HK's endcap. Go to Adam Weber's sight and look at the pictures. The HK stock costs substantially more also.

Could you be a little more detailed on what you mean by wobble on the stock?  Do you mean that when the stock is extended there is back and forth play in the hinge or is it the receiver to stock fit that is the issue.  I have the Choate with the adjustable length of pull and the stock locks up rock solid.  Mine's not on a K model but a MKE.

Thanks for the feedback, gentlemen.

For now, I'm content with using a 1-1/4" long, 8-32 tpi button head cap screw and nylon locking nut to fix the forend.  I just finished the project. It locks up rock-solid now, and since both the screw and nut are matte black, you hardly notice it is different from the push-pin.  Problem solved IMO.

As for the buttstock, yes, there is a teeny tiny bit of wobble in the Choate locking mechanism.  That is about 10% of the problem. The other 90% is where the stock end-plate interfaces the receiver. Remember that I have an MP5K, so I'm using two small push-pins to make the connection.  I have substantial in-out, up-down, and left-right play in the lower push-pin hole, and substantial up-down play in the upper push-pin hole.

If I attach the stock to the receiver, and then pull the stock and receiver away from each other, I can slip a 0.020" feeler gauge between the receiver and end-plate.   I removed the buffer, and the feeler gauge can slide right through the gap.

I'm actually thinking about trying to shim the end-plate in hopes of tightening things up a bit before I spend 2x-3x on a B&T stock.

I shimed mine with a little electrical tape.  Others have had good luck with a rubber o-ring

http://www.hkpro.com/forum/hk-nfa-talk/211550-mp5k-stock-wobble-9mm-ejector-lever-marks-question-see-pics.html