While waiting on my 3d Printer to print some things, I took some time to design my own stock adapters for a 1913 rail and for the ACR folding stock. People who have been here for a while will know that a few people have made these adapters over the years, with the most recent designs from Lucky Irishman who appears to be withdrawing from the business. To fill that void, I've decided to make my own. While the ideas are similar, I didn't use any of Lucky Irishman's data to make these; just measurements and observations on what I've learned about these platforms. I would like to give credit to 3D print group AWCY? for releasing the CAD models of the ACR folding stock end to the public; this project was made much more easier thanks to their hard work.
My idea is to produce two options for each adapter. One, a full-featured, CNC-machined aluminum adapter that has QD sling points and threaded holes both to screw into the XCR lower and to screw in the sling loop in the original ACR folding stock. Machining the 1913 rail is very simple, however, I can't think of an easier way to machine the ACR folding adapter without having to invest in a 5-axis machine. The other, more tangible option now, is to produce simplified and affordable 3D printed adapters for people who need one right away and don't need special features. While they won't be metal, and you have to be weary of keeping them in a hot car approaching 140 degrees F, they will be made of the best material available and they are all very sturdy and simple to install.
CAD models for the ACR folding stock adapter:
CAD models for the 1913 adapter:
The ACR adapter fresh off the printer:
The 1913 rail adapter:
Support material removed:
The nice thing about the 1913 adapter is that it replaces the need for a pistol endcap or fixed stock adapter.
Both adapters have clearance holes so a 1" long, 1/4-20 thread screw can reach through and screw into a nut on the other end.
I still need to install these things onto my rifle and test them for strength. Will report back when I get the chance to do so. Eventually, I'd like to make stock adapters for a buffer tube extension (so you can use AR stocks on the XCR) and an adapter for the Magpul Zhukov stock (I'll need a Zhukov first). Any ideas or critiques are welcome.