Lets you put folding stocks on AKs that normally wouldn't be able to take them. You can now put skeletal triangle stocks on the Saiga, AR-15 stocks on the AKS-74/AKS-74U, and all that good stuff or something.
Advanced Custom Weapons probably already does this, or at least, it should. Don't install if you're already using that or something.
Just a few of the 391 users online
UprootedSeeker
Does advanced customs weapons do everything your mod does?
I couldn't tell how certain you were by your description... it sounded like you thought it might but weren't sure.