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View Full Version : Building a MAC-10/9 from a parts kit and receiver flat: Legality


chead
07-11-2011, 1:32 PM
I'm really interested in building a MAC-10 9mm from a kit and flat, but I can't seem to find any information about how to do this as a closed-bolt semi. Obviously a closed semi bolt is required but are there any other modifications that need to be done to the receiver (from a flat)?

Can I just drop in a semi FCG and bolt and be good to go?

Oceanbob
07-11-2011, 2:13 PM
I wish I knew..I have a MAC 10 9MM (raw) and it fires from an open bolt.

762.DEFENSE
07-11-2011, 2:27 PM
I wish I knew..I have a MAC 10 9MM (raw) and it fires from an open bolt.

Lucky! :pinch:

ke6guj
07-11-2011, 2:38 PM
I'm really interested in building a MAC-10 9mm from a kit and flat, but I can't seem to find any information about how to do this as a closed-bolt semi. Obviously a closed semi bolt is required but are there any other modifications that need to be done to the receiver (from a flat)?

Can I just drop in a semi FCG and bolt and be good to go?

yes, you can basically buy a semi-auto closed bolt flat or 3-piece weld together receiver, finish up the receiver, drop in your closed bolt parts and be good to go. You do need to transition through a roster-exempt configuration upon initial build.

WTSGDYBBR
07-11-2011, 2:42 PM
I got a mac 11 closed bolt . I would love to build one they look very easy.

chead
07-11-2011, 6:07 PM
So there's no lower receiver differences between FA and SMG? And is it okay to use an SMG kit for parts and a newly manufactured closed bolt and semi FCG? I don't see many dedicated semi kits, I assume because you can buy semi MACs (no need for a kit). I would far rather build from a kit and have something "classic", and the fun of bending and welding a flat! I'm going to need a few flats for the first two I will no doubt mess up haha.

ke6guj
07-11-2011, 6:36 PM
So there's no lower receiver differences between FA and SMG?right, an SMG is FA. And an open-bolt semi receiver is basically the same as the FA/SMG receiver. A closed-bolt SA receiver is different.


And is it okay to use an SMG kit for parts and a newly manufactured closed bolt and semi FCG?if you wanted to. The only thing you would end up using would be the barreled upper and the magazine catch parts. No point in buying an SMG kit and replacing 50+% of the parts with SA parts.

chead
07-11-2011, 6:50 PM
Ack sorry, meant "different between SMG and SA". As I understand it, open bolt semis are NFA items, so I would need to go closed bolt. But is the closed bolt receiver different from the SMG/open bolt semi? None of the flats I'm looking at online seem to specify one way or the other and I don't know what to look for to determine which is which.

chead
07-11-2011, 6:57 PM
if you wanted to. The only thing you would end up using would be the barreled upper and the magazine catch parts. No point in buying an SMG kit and replacing 50+% of the parts with SA parts.

I realize, I just want to do it myself. I have seen a few closed bolt semi upper kits, but they seem to be far rarer than the SMG kits, again I assume because people buying closed semis are doing so as complete guns, so there's not a lot of demand for receiver-less kits. I'm just looking forward to building it up myself, and replacing parts would actually be fun as part of the project just to see what does what. The MAC is a pretty simple gun, but when I'm done I want to feel like I "made" it, not just lego'd it together.

ke6guj
07-11-2011, 7:02 PM
yes, the closed (CB) bolt semi receiver is different than the SMG/open bolt semi. the FCG has a different bolt pattern. If you find a flat, it must be a CB semi flat.

If you buy the weld-together receiver, the side plates must be undrilled or drilled with the CB hole pattern. The lower section of the receiver in the weld-together kit is interchangable between CB and OB/SMG.

the weld kit with the grip and trigger guard is interchangable.

chead
07-11-2011, 7:06 PM
Ohh, that makes way more sense. Are there diagrams I can use? Is there a proper name for those stick-on guides for receivers that show where to drill the cb holes, etc?

e: The flats I'm looking at are literal "flats" with no holes, which means they have to be drilled for the cb semi action?

ke6guj
07-11-2011, 7:09 PM
I realize, I just want to do it myself. I have seen a few closed bolt semi upper kits, but they seem to be far rarer than the SMG kits, again I assume because people buying closed semis are doing so as complete guns, so there's not a lot of demand for receiver-less kits. I'm just looking forward to building it up myself, and replacing parts would actually be fun as part of the project just to see what does what. The MAC is a pretty simple gun, but when I'm done I want to feel like I "made" it, not just lego'd it together.

I understand what you are wanting to do, but just swapping out a bolt and FCG and throwing away that money doesn't sound like "fun". I would suggest calling the Mac-10 suppliers and just asking them if they have, or can make, a semi-auto kit for you. No point in spending ~$350 for a SMG parts kit, tossing the $90 FA bolt and all the FA FCG parts, spending another $125 for a SA bolt and whatever $$$ the SA FCG parts will cost. Call up Cobray or FTF and see what they can do for you. They do have stuff that they don't list on the websites.

chead
07-11-2011, 7:13 PM
Oh dang I didn't even think of calling Cobray direct, they probably will have what I need.

ke6guj
07-11-2011, 7:14 PM
Ohh, that makes way more sense. Are there diagrams I can use? Is there a proper name for those stick-on guides for receivers that show where to drill the cb holes, etc?

e: The flats I'm looking at are literal "flats" with no holes, which means they have to be drilled for the cb semi action?

yes, there are probably "templates" out there for the drill pattern.

If you can find the pre-drilled sideplates that you weld to the center section, that might be easier.

Are you more interested in an Mac-10/9 vs an M-11/9. If you aren't stuck on a Mac-10/9 you might want to look around to see what kits are available for the other types


Oh dang I didn't even think of calling Cobray direct, they probably will have what I need.
yup, or email them. I emailed both companies and got the basic info I needed before I picked up the phone and did a package deal for some kits.

chead
07-11-2011, 8:24 PM
yes, there are probably "templates" out there for the drill pattern.

If you can find the pre-drilled sideplates that you weld to the center section, that might be easier.

Are you more interested in an Mac-10/9 vs an M-11/9. If you aren't stuck on a Mac-10/9 you might want to look around to see what kits are available for the other types

In theory I'm okay with an 11/9 but I keep seeing great deals on kits for one or weld kits for the other. If the stars align and I find everything I need and want, I'll go for it regardless of it's a 10/9 or 11/9.

The side plate weld-up kits I've seen don't have any holes, but I assume that's just so you can use them for whatever. I guess in theory if you had a registered receiver SMG you could repair it with them.

Just to clarify: It is NOT legal to do an open-bolt semi, right? And the only ones available are grandfathered, considered machine guns, and now NFA items, correct?

ke6guj
07-11-2011, 8:29 PM
The side plate weld-up kits I've seen don't have any holes, but I assume that's just so you can use them for whatever. I guess in theory if you had a registered receiver SMG you could repair it with them.I don't recall who had them, but they do offer the side plates predrilled for a CB semi, at least they did for the M11/9.


Just to clarify: It is NOT legal to do an open-bolt semi, right? And the only ones available are grandfathered, considered machine guns, and now NFA items, correct?
correct.

chead
07-11-2011, 8:34 PM
Okay, cool, that's what I sussed out, but it's weird that there isn't some good repository of non-NFA (or both) MACs out there. I assume subguns would be offended just at the idea of building a CB SA MAC :p

chead
07-12-2011, 11:59 AM
How bent does a flat have to be before it's considered a receiver? Is flat with the sides bent but not the rear an "80%" or does any bending at all make an FFL necessary?

ReddingShooter
01-20-2016, 11:58 AM
if your gonna go thru all that, find a used one and buy it already done. cheaper in the long run.

Carcassonne
01-20-2016, 6:39 PM
I'm really interested in building a MAC-10 9mm from a kit and flat, but I can't seem to find any information about how to do this as a closed-bolt semi. Obviously a closed semi bolt is required but are there any other modifications that need to be done to the receiver (from a flat)?

Can I just drop in a semi FCG and bolt and be good to go?


Do you mean a real MAC 10 or an M11/9?

The MAC 10 has a fixed firing pin and only fires from an open bolt. The M11/9 has a floating firing pin and a hammer.


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chead
01-21-2016, 8:34 AM
Do you mean a real MAC 10 or an M11/9?



The MAC 10 has a fixed firing pin and only fires from an open bolt. The M11/9 has a floating firing pin and a hammer.





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Whoah, thread resurrection!

M11/9, I was curious about what needs to be done to adapt a MAC 10 kit for a closed semi bolt and if that requires modification to the receiver (like the "blocking bar" used in semi Uzi kit builds).

Carcassonne
01-22-2016, 9:06 AM
Whoah, thread resurrection!




:facepalm: I didn't notice that. Someone before me bumped the thread.



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chead
01-22-2016, 9:07 AM
:facepalm: I didn't notice that. Someone before me bumped the thread.







.


No problem, I'm still interested in the prospect :)

Quiet
01-22-2016, 10:24 PM
Keep in mind that if you are attempting to do this now (post 01-01-2015), then, in order to be CA legal, it needs to be built as a dimensionally complaint (minimum 6" barrel length + minimum 10.5" overall length) bolt-action single-shot pistol or as a dimensionally complaint (minimum 6" barrel length + minimum 10.5" overall length) break-top/open single-shot pistol.

Carcassonne
01-23-2016, 7:39 AM
Keep in mind that if you are attempting to do this now (post 01-01-2015), then, in order to be CA legal, it needs to be built as a dimensionally complaint (minimum 6" barrel length + minimum 10.5" overall length) bolt-action single-shot pistol or as a dimensionally complaint (minimum 6" barrel length + minimum 10.5" overall length) break-top/open single-shot pistol.


But he did build it before 01-01-2015 :43::43::43:


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