Well after several years shooting the rifle (~4000 rounds) and upgrading from the original ACE stock to the FAST stock, I finally decided I didn't care for either of those options and wanted to go for an AR-15 stock on my XCR. It seems that ship has sailed somewhat... as after several weeks of searching, and offering over brand new value for several NEA adapters on the EE, I was unable to acquire one. This seemed like the best option, as it looked like it had the stock height roughly correct for use of AR-15 height optics/sights/mounts. Can't tell for sure from the pictures, but it looked like it added more to the length of pull than necessary, and the XCR receiver already sticks back a ways, so would have limited the useful adjustments on most stocks (unless you happen to be a gorilla...).
I realize the Dlask adapter is still available, but I am really not a fan for these reasons:
1) Stock height appears to be set inline with the bore, as on an AR-15. While this is perfect for the AR, the XCR is taller due to the gas piston on top, so setting the stock concentric with the bore means all of the AR-15 height optics/sights and mounts will result in pretty much no cheek weld. I am a firm believer that a proper cheek weld is pretty much required for quick/accurate shooting, so I didn't care for this.
2) Doesn't look like you can use AR-15 end plates on this adapter, so no QD end plates. Also doesn't look like it would work with stocks like the UBR (I may be wrong here...)
Frustrated by my options, I hopped on Solidworks earlier this week and whipped up an adapter of my own. My original (and not off the table just yet...) plan was to have this CNC'd out of aluminum and cerakoted. While this may still be an option, I am pretty sure I don't want to see what the cost to produce just one on a CNC machine would be. Then on Friday I had the idea to see if I could find someone to 3D print one for me... a quick google search yielded several options in town. I modified my model slightly for 3D printing (exact dimensions for the buffer tube threads added, receiver bolt threads replaced with a cutout to hold a 1/4" nut as I didn't trust 1/4" threads in a 3D printed part) and sent it off. Within about 5 or 6 hours my part was printed and I cruised over to pick it up. The first piece looked great, but had a couple of small issues. Another hour or so of careful measurements and some destructive testing, and I was able to modify my model to fix a dimensional error (my fault...) and account for some of the intricacies/tolerances associated with the 3D printing process. Version 2 fits like a glove and was printed with fully functional 1 3/16 -16 receiver extension threads. No need to clean up with a tap even (This impressed me the most for my first real experience with 3D printing...).
Anyways, here it is!
I designed my adapter to achieve the same stock height with respect to the top rail as an AR-15, so standard sights etc feel very familiar. I also tried to keep the additional LOP to a minimum, but using the nut instead of tapped threads for the attachment bolt through the receiver meant I had to add a little more than I would have liked. It may still be possible to shave 3/16 - 1/4" off of it later, but as it without a jacket on I prefer it in position 3 or 4 out of 6 so its well within the usable range for me. The current part is printed using ABS with a 100% in fill, but I am still not fully confident in its strength. Judging by my destructive testing of the first one (though only 25% infill on that one...) one rough hit to the side of the stock/receiver (think bending the buffer tube sideways) and I am pretty sure it will snap either at the receiver or the buffer tube threads. Probably not the end of the world to have the adapter as the weak point, but I would like it to be a little tougher than it is now. Currently looking for someone to print it out of some hopefully tougher Nylon and see if that works better.
I realize the Dlask adapter is still available, but I am really not a fan for these reasons:
1) Stock height appears to be set inline with the bore, as on an AR-15. While this is perfect for the AR, the XCR is taller due to the gas piston on top, so setting the stock concentric with the bore means all of the AR-15 height optics/sights and mounts will result in pretty much no cheek weld. I am a firm believer that a proper cheek weld is pretty much required for quick/accurate shooting, so I didn't care for this.
2) Doesn't look like you can use AR-15 end plates on this adapter, so no QD end plates. Also doesn't look like it would work with stocks like the UBR (I may be wrong here...)
Frustrated by my options, I hopped on Solidworks earlier this week and whipped up an adapter of my own. My original (and not off the table just yet...) plan was to have this CNC'd out of aluminum and cerakoted. While this may still be an option, I am pretty sure I don't want to see what the cost to produce just one on a CNC machine would be. Then on Friday I had the idea to see if I could find someone to 3D print one for me... a quick google search yielded several options in town. I modified my model slightly for 3D printing (exact dimensions for the buffer tube threads added, receiver bolt threads replaced with a cutout to hold a 1/4" nut as I didn't trust 1/4" threads in a 3D printed part) and sent it off. Within about 5 or 6 hours my part was printed and I cruised over to pick it up. The first piece looked great, but had a couple of small issues. Another hour or so of careful measurements and some destructive testing, and I was able to modify my model to fix a dimensional error (my fault...) and account for some of the intricacies/tolerances associated with the 3D printing process. Version 2 fits like a glove and was printed with fully functional 1 3/16 -16 receiver extension threads. No need to clean up with a tap even (This impressed me the most for my first real experience with 3D printing...).
Anyways, here it is!
I designed my adapter to achieve the same stock height with respect to the top rail as an AR-15, so standard sights etc feel very familiar. I also tried to keep the additional LOP to a minimum, but using the nut instead of tapped threads for the attachment bolt through the receiver meant I had to add a little more than I would have liked. It may still be possible to shave 3/16 - 1/4" off of it later, but as it without a jacket on I prefer it in position 3 or 4 out of 6 so its well within the usable range for me. The current part is printed using ABS with a 100% in fill, but I am still not fully confident in its strength. Judging by my destructive testing of the first one (though only 25% infill on that one...) one rough hit to the side of the stock/receiver (think bending the buffer tube sideways) and I am pretty sure it will snap either at the receiver or the buffer tube threads. Probably not the end of the world to have the adapter as the weak point, but I would like it to be a little tougher than it is now. Currently looking for someone to print it out of some hopefully tougher Nylon and see if that works better.
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