I have been incapable of finishing a decimator build with an OEM barrel; 2 different OEM barrels as a matter of fact.
I’ve reprinted the upper twice (once because I wasn’t sure if I just really messed up the print, once for stripping barrel nut threads) and I’ve reprinted the barrel nut 3-4 times at this point.
I started this build just before fosscad was nuked, and since the Ark is back up (https://forum.guncadindex.com/c/ark@fosscad.io), I was able to see that there are threads where others have had this issue.
Has anyone overcome this issue personally? The build looks great and I love the AR fcg but I’m hitting a wall here. Should I just drill and pin the barrel nut with a couple of set screws?


If I recall correctly, he oriented the barrel nut super weird, with the bore facing sideways. I did mine vertical and it threaded on fine but he had a good reason for that orientation.
Have you done dimensional calibration, like a calilantern?
Yeah, I ran into the same thing with the orientation; got farther after orienting it vertically, but like you said, he had a reason for the original orientation.
And I have not done that; I’ve never even heard of the calilantern. I will for sure give that a go. Thanks!
It helps a lot with threads, and under/over extrusion. If you need the files DM me, you’re not supposed to share them cause OP has cancer and he sells them.
Hey, thanks again for the assistance! I didn’t get back to this for awhile; life things. I left an update up at the top for anyone in the future.
I appreciate it! I’ll throw him a few bucks for his work and guide. Wouldn’t want to see that become standard in fosscad or a lot more people would end up losing fingers, I think :p