Ghost Gunner and MPCNC Possibilities

While I don’t own a firearm, I’ve always been intrigued by the incendiary topic of Ghost Gunner. Basically, they sell a CNC machine ($2K) for a private US citizen (in most areas) to legally finish producing their own firearm by milling the last 20% of an 80%-complete “lower” of an AR15 (and you buy the other pieces of the assembly for a full-working model). They, of course, sell the 80% lowers made of 7075 billet aluminum. I know very little about weapons, but I gather the “lower” is what’s needed to tie all the other purchasable pieces together and make a working unit. Evidently, this dodges some sort of regulation, but I haven’t reviewed the legalese on what that exactly is.

So, has anyone looked into and/or knows the trade well enough to know if the MPCNC (probably a smaller one) can operate at the tolerances required and leverage the digital files to finish producing the “lower”?


We’ll I didn’t exactly do a lot of research, but after looking at a few videos the milling apparatus is oriented to a different axis than a MPCNC, so I imagine there would be a lot of pain/trial/error getting that to work. Looks like a no go.

My understanding is the MPCNC can mill aluminum in very close tolerances but if you’re talking full auto, I can strongly suggest don’t unless you want to stay in prison for a big number of reasons. has a slew of info and videos to walk you through the milling process. I have seen what appears to be a little chatter in the video where they made a small plastic injection die of an AR15. It was phenomenal in detail but, it needed to be polished to a mirrored shine. I think the MPCNC could, if you spent years fine tuning your skills. You’d be better off buying the gun semi-auto and leave it at that.

These workarounds you see change state to state but on the Fed level, they are totally prison time. Gunsmiths need all kinds of licensing to make what you’re talking about. It would be cool but not if you get caught…

I hope this helps.

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Thanks for the cautionary advice. BTW, nothing about this is in regard to full-auto or the desire to do so. This is about manufacturing a legal firearm adhering to all federal regulations (not about circumventing laws, etc). I have no interest in joining those folks in the clink, but rather guarding myself and family from those recently lodged (or will be by their own foolishness) there.


Oh, and seriously…where’s the fun in buying one? Most folks on this forum are likely about making something, whether they need to or not.

I’ve seen guys mill out 80% with a jig and a hand drill. IF your bit can reach the depth it needs I wouldn’t worry about having enough precision.

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The lower is the part of the gun that has to be stamped with a serial number when you buy from a manufacturer. If you make your own lower then you can legally piece together a gun without a serial number… (Texan here. But you might want to check your local jurisdiction.)


I’m an ex-cop that’s white living in an all black neighborhood. I don’t have anything except a Remington 1100 12 G auto that’s sawed off and pistol gripped. It’s choked too to create a smaller group pattern at close range - like inside my house. All the people know me. I’ve arrested some, ticketed others and more than once helped many of their families after I did so. Still, I’m not prone to taking chances. First round is rock salt, after that, it’s lead. And ammo is way cheaper. :slight_smile:

I wouldn’t try it. The lengths you’re going to need aren’t going to work well with the mpcnc. At most for aluminum we’re running out of rigidity at around half, to three quarters of an inch(tool length). After that it’s going to be chatter city.


Kind of a funny coincidence, this guy is doing it by hand with a jig with what looks like a DWP611

But yeah, you gotta reach DEEP!

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That “drop it in at an angle” approach is SCARY!!!

That’s why I think the mpcnc won’t work for this. That end mill is waaaaaay too long for our machine.

Yup, that looks real scary. Deep and scary. Maybe a better router? A longer endmill?. Scary. I’ll stick with the 12 guage.

Don’t forget a tornado knife belt for backup!

He cut himself towards the end pretty good.

You can get one for $30, here in ND my local FFL will run the required paperwork for an additional $20.

I believe the 80% lowers are more expensive, not to mention the jig required. I get that it’s cool to have an untraceable home manufactured rifle, but it’s lots more money.

But then the man knows I have guns!!! :roll:

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What a moronic idea.

I love the US and I’d love to live there at some point, but there’s just way too many war weapons in the hands of any random idiot. Super scary.

Those guys will likely damage our hobby at some point, let’s hope there wont be any major incident or we might see more and more constraints on what we can and what we cannot do in the homeshop.

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If you don’t live in a free state, then you may need to check your local laws. Otherwise everything said here is perfectly lawful (and quite fun). AR lowers are cheap and easy to print. You can find several different models in the FOSSCAD repo on GitHub. As others have mentioned, the limiting factor of the MPCNC is stick-out, which makes the deep pocketing operations like for the trigger pocket more dicey.

Fortunately there are other ways of skinning this particular cat.

One idea that I’ve been toying around with is splitting the lower in half, milling each side, and then bolting them back together like this. This would mean milling from 0%, and both sides would fit on a 9"x6"x0.75" piece of bar stock. Keep in mind this is an early concept, and the buffer tower would likely have to be made its own piece in order to maintain strength when reassembled.

And of course there is also the already existing Bolt-together AR lower concept, which should be significantly closer to this machine’s capabilities.

Personally, I’m a big fan of this machine and intend to continue to explore its usefulness in amateur gunsmithing. To that end, a much simpler project in Aluminum like the FreeMenDontAsk Glock 17 Rail inserts would probably be a good starting point (and where I intend to start as well).

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I needed that good laugh. Thanks.

That was my thought as well. If someone isn’t using the gun for illegal activities, who cares if it has a serial number. The hobby is cool but it takes one knucklehead and a lot of people die. I found that I am really uncomfortable with making these things - legal or not. We have enough crazies with assault weapons without adding unregistered guns to the mix. I like to build guns - percussion cap black powder rifles, pistols, and cannons but I think this assault rifle activity is a bridge too far. Just my take on it.