I get what you mean now. I'm just hoping my filaments will hold up after I print and test with them; I don't need any false negatives or positives from the plastic warping after the fact. One of these days I'd love a sintered metal printer or mold, but first the need must match the ambition.
Think 4140 would work for the bolt catch? I got some of that lying around, not sure how I'm gonna harden it though if at all; not looking forward to grinding off the scales after oil hardening.
On that note I'm a little bummed that I have to make a new, longer bolt catch for this lower. Maybe I can get away with making a threaded extender that goes between the original bolt catch and the foot release? For that matter, I could look into making copies of the XCR bolt release and mag well parts if we want an alternative source for these parts.
I'm not looking to get into the stock adapter business, Lucky Irishman seems to have that covered (for as long as he can stomach it anyway). Haga Defense makes a 1913 stock adapter for the ACR stock, and Kinetic Development Group seems to have a steady supply of the ACR stock readily available for what ever rifle you need it for (there's probably more ACR stocks than ACR rifles that might need them). I'm also comfortable knowing that there is an adapter that connects a buffer tube to a picatinny rail
out there. So with that, I feel like the 1913 rail is very versatile option to rely on. It's also relatively easy for me to design and machine, since I've made picatinny rails before.
Sure, like I always say, if the toy you want doesn't exist, make it yourself. Still, I feel like this is something that at least a few people would want, and I want to be able to help with that. And while it would be nice to make a side business out of building metal parts out of my garage for a bit, it's not going to blow up with just one design. Leemajors and MountainMan's experiences with making parts for this community have really colored my expectations for this kind of work, so I just want to make what I design available to people who want them (I'm still looking for takers on that DP-12 rail I made, lol). That can mean partnering up with a Form 7 FFL or just making the mechanical drawings available for people to make their own, we'll see what happens.