ACE makes two adapters, one of which IIRC will fit the R22 and allow different stocks to be used. Can anyone tell me which adapter is the correct one to fit the R22 (I recall a simple mod needing to be done to the adapter, not sure though)?

HK 93 receiver block. Length .500". Use SMG Folding stock mechanism / 1 1/4" sling swivel. Weight 140g ( 5 oz)
HKRB93..........$ 50.00

HK 94 receiver block fits the HK 94 and MP5 variants. Use SMG Folding stock mechanism with sling mount. Length .375" Weight 90g (3.2 oz)
HKRB94..........$ 60.00

Do you already have the G3 stock adapter from Rhineland??  I've ordered one, but I think I'll have to call and hustle it along.  If you've got the RA stock adapter, you should be able to use the Ace Ltd reciever adapter for the G3/91.  

let me know how it works out.  I want to install one as well.

I'm still waiting to get my rifle back from RA :)  RA does good work but they have an issue with getting ahead of themselves on new projects before old ones are fully taken care of.

I hear ya.  It took a few months to get a replacement stock.  I'm still waiting on the stock adapter I'm paying for.  I think the product is great, and I love the innovation and involvement in the product.  I'm afraid the Canadian importer may bail on the line because of the delays in getting some of the last shipment up and running.  

Mine works like a champ, and I've probably got 2k on it already.  Short of getting filthy or feeding it crap ammo, it runs like a Timex.

Seems like lots of people like it, especially the people who have the first gens that had them modified...I really want mine back, I can't wait to shoot her again, this time I think she'll be awesome...I just miss her is all, it's been about four months now.

p.s. Where'd you find out about the G3 stock adapter?

I talked to Cheaper Than Dirt - they currently have a G3 OE stock kit, but they refuse to ship it to California because the kit has a pistol grip in it and god forbid one of those gets sent to CA, it might get put on a .22 or something lol.