Modifications Of Your Own Mac Machinegun Receiver

[A&S Conversions]

Possible to do anything you want. If you’re just doing it to your own piece, the ATF probably doesn’t care. Might make it impossible to transfer and one less piece on the registry when they become aware. If you’re talking about developing a product for market, seeking ATF approval, some posters here can probably give you some cautionary tales.

This was posted on another thread. Instead of derailing that thread I thought that it would be better to start a different thread.

This post was something that I forgot to comment about. Whether you modify one or 1,000 registered receivers, the ATF does care. The only thing that changes is the odds of being caught. It is my understanding that the ATF has settled on 80% of original for whether firearm receiver is still a firearm, with a focus on fire control and mechanism (the recoil spring). There is a separate issue of proper destruction with a machinegun receiver.

It is my understanding that for a machinegun receiver to be legal for a private individual, that receiver would have been made and registered by May 19, 1986. The ATF position is if they determine that there is less than 80% of the original receiver remaining, that machinegun receiver is no longer transferable.

Of course the ATF is not going to prosecute what they are unaware of. Is a private individual who modified their machinegun receiver likely to be caught? No, but to legally defend the penalties that would occur would probably cost more than a Colt M16A2. Beyond the money is going to Federal Prison for 10 years. The only penalties for driving around without insurance is lesser than owning a questionable legal machinegun. The odds are are very low that I would be at fault in a major accident with loss of life, but I have no plans to cancel my auto insurance. This is a personal decision.

This is a forum for adults. I am certain, the ATF does care what and how you modify your machinegun receiver. If that is a risk you wish to take, you are responsible for the consequences if found out. I just wanted to be clear that I feel that the post above was incorrect, and why I think so.

Scott

 

[Deerhurst]

Why are you starting a thread for this? Feels kinda like a rant.


Also, FATF.

 

[A&S Conversions]

Because the post that I quoted was on the "3D Printing Chassis" thread. Modifying a RR IMHO doesn't have very much to to 3D printing. I had missed what was in that in post that I quoted in my first reading. So I wanted to post my understanding of how the ATF views registered receiver modifications to be a counterpoint to what had been posted.

If the poster that I quoted wants to modify their registered receiver, that is their choice. The point of my post was for those searching for information about modifying their registered receiver some time later. I don't claim to know everything, but since submitting for determinations to the ATF, I feel that I have a decent knowledge base of what ATF would or should allow.

When I make a post about a specific subject, I am looking for information about that subject. I find it frustrating when I search for information and a thread about the subject has two or more members arguing about something that has nothing or very little to do with the subject of the thread that I was searching. I am trying to be respectful of the OP, so their thread isn't taken off track by a side issue.

Scott

 

[woodenword]

In the other thread, the OP was talking about removing the mag well. Are you saying that you believe that putting a different mag well on an M-11/9 is an illegal conversion? What about when Practical Solutions changes an Mac 10 to an Uzi mag well? And would either even be considered a permanent modification?

 

[Galil#1]

BTW... The MAC 10/9 to UZI mag well conversion is the best mag conversion ever - Thank You Sam/Practical Solutions!

 

[theduke]

I didn't follow other thread.

Magwell conversions are nothing new.........I'm not sure what this 3d printed fukall is all about.....an adapter? I doubt it as that ain't permanent.
Its a bit of a mystery but does make sense.

I don't think I'd attempt to gut my M11.......squash it to round and scab on a sten.......or convert to M16 FCG..or some other Kentucky Ballistic experiment.

 

[A&S Conversions]

In the other thread, the OP was talking about removing the mag well. Are you saying that you believe that putting a different mag well on an M-11/9 is an illegal conversion? What about when Practical Solutions changes an Mac 10 to an Uzi mag well? And would either even be considered a permanent modification?

No, the channel with the boxed in end is the Mac style registered receiver. I mentioned in my original post in this thread, the magwell is welded on but is not the RR. Another member made a modular magwell that was held onto the receiver with a single screw. I think that a more refined magwell system would be a real plus.

The point I was trying to make is that just because the individual owner modifies a registered receiver machinegun, just because it is just one doesn't mean that it can be modified any way that the owner desires. Whether it is modifying one or 1,000 the modifications need to be within their guidelines.

Scott

BTW, I have two Uzi magwell conversion M10s.

 

[LawBob]

Unrelated but fyi

My serial number is a little “light”

My friend sot who does laser engraving said you cannot touch an existing SN… does that mean modify or highlight? Indeterminate.

However nothing prevents you from putting an additional matching info elsewhere.

I thought I might do this to my Texas mac just in case a couple parks later the old one dissolves.

IdentMarking.com

 

[Tinman45]

Scott, my post was a bit flippant and wasn’t intended as legal advice by any means. I will cheerfully defer to your greater experience with ATF. Cheers.

Tin

 

[A&S Conversions]

No worries, thank you for the clarification. I have seen on other forums where members have posted that as long as there is paperwork, it doesn't matter. I find such sentiment concerning. Again this is a forum for adults. Each of us decides what their priorities are. I would hate to think of someone making a poor decision because they found bad information.

Scott

 

[Tinman45]

I don’t disagree and I take your point. The post could have been better advised and worded more carefully.

 

[brenbuilds]

Magwells are not part of a MAC's receiver, hence exemption. The MAC receiver is the folded flat that was serialized; magwells being separate units welded to the receiver.

 

[jkacg1]

Magwells are not part of a MAC's receiver, hence exemption. The MAC receiver is the folded flat that was serialized; magwells being separate units welded to the receiver.

Would this be true of say a Stemple 76/45 also? I ask because there is a well-known company that works on these firearms that will not alter one that has a welded-on magwell.

 

[smec_289]

Would this be true of say a Stemple 76/45 also? I ask because there is a well-known company that works on these firearms that will not alter one that has a welded-on magwell.

Stemple seems to be pretty forgiving. I bought a STG recently and after talking with Brian I was amazed what all he has been able to do with the registered tubes. Great guy by the way. Still think the Ingram family is one of the most versatile. It was a good stroke of fortune that the lowers were serialized rather than the uppers or this community wouldn't exist as it does.

 

[smec_289]

Old thread on grip replacements. I had wanted to do this but now the guns are expensive enough that it makes me nervous to cut one up and all the steel Glock frames are long gone anyways. https://www.uzitalk.com/forums/index.php?threads/glock-grip-conversion.95917/

 

[brenbuilds]

Would this be true of say a Stemple 76/45 also? I ask because there is a well-known company that works on these firearms that will not alter one that has a welded-on magwell.

I suspect they are hesitant to modify or remove a serialized part. I believe all Stemple's had their tubes registered, but also bore the make/model and serial on the magazine well. It could constitute "marrying" like you see with some HK's