Not sure why a Tapco collaspible wouldn't fit the Mak, the Mak 90's stock fits a standard fixed stock trunion. Since you say they're not compatible perhaps some pictures or more info would help answer your question.
I don't know why either. The site says it won't. Ive read MAK stamped recvrs are a little thicker steel, maybe thats why.
Edit: You have to click "Item Specifications" tab, after clicking the link to get to the "will not work part"
Well I have had a Mak 90 thumbhole stock on my Romanian build and didn't have any issues, but haven't had any Mak 90s. There are several adaptors out there for the AK to use the AR stocks, I'm sure one would work. In the worse case scenario you would have to 'modify' it some to fit (Dremel = modify). I hope that helps. Without seeing it in person or getting dimensions it's hard to say. Personally I don't like Tapco after we had two of their stocks break for no apparent reason at a mid winter range date after building several AKs. Considering how easy they snapped and how cold it was I assume the plastic couldn't handle the extreme cold. But having said that, I would ask Tapco. Either they could explain to you what limitations they're concerned about or be able to give you measurements to see if they will fit yours.
Thanks for the Tapco warning.
Do you have a opinion on this product?
Mako SBT-K47FK Collapsible Buttstock
I think I will contact the Manufacturer to verify fit, but it says it fits all receivers. I might have to get experimental
and attempt to fit it myself. I like the sound of the "recoil reducing buffer"
Interesting concept. No, I have no experience with that one but my brother has another one of their furniture configurations and likes it. But he doesn't get out in the middle of the winter to shoot it so I have no clue on it's ability to withstand the cold. I have several AKs with the original synthetic stocks and they haven't had any issues with the cold so synthetics can do it, just not this cheap moldings many US have done.
The only issue I think is that Chinese receivers are thicker so you'd have to take a little material off of the sides where it enters the receiver.
The fit issue with the MAK90 is that some of the receivers are what is referred to as slant-cut. This means that instead of the back of the reciever being square, some of the MAK90's have the back of the reciever cut at an angle as part of the AWB nonsense. If the back of your reciever is square, you are GTG with the exception of some possible fitting for variances in thickness of the receiver and such as noted above. I haven't looked recently, but as far as I know, only Ironwood Designs makes a stock made specifically to fit the MAK90, but that's a traditional wood stock.
Here's a photo I dug up on the net of a slant cut receiver with a standard stock installed:
The receivers of the MAK 90s are a little thicker. Some will take an aftermarket stock fine, some need a bit of fitting.
Our system is designed to adapt to varied receiver dimensions - it slides in and then expands to fit. If it is too tight, it may take a little fitting, but that is just a couple minutes with a file. If it is just a little tight, you may need to get a slightly longer screw to replace the front screw that ship with out adapter, if file the adjustment wedge slightly. Otherwise, it should be a drop-in fit.
As far as durability and cold, I live in Alaska and have not had any issues in the winter. I am about to do some cold-weather abuse videos. These polymers exceed MIL-SPEC specifications, and this product is in use by foreign militaries.