DUAL MAC UPPER project (DMAC/RR20)

[strobro32]

Fun. You have me wondering just how many uppers could a single SMG lower operate at the same time?

 

[rybread]

Fun. You have me wondering just how many uppers could a single SMG lower operate at the same time?

These are all 1 lower to 1 bolt. Could a single lower operate multiple uppers? You bet, almost anything is mechanically possible. In theory.. one sear plate that interacts with the single lower sear- that sear plate hosts multiple sears that are only engaged to retain other bolts when the plate is back far enough to be engaged on the primary sear. The primary sear plate would have one fixed bolt, to power it... could run a bunch of channels - up until the sear plate & attached parts became too heavy. Otherwise pretty simple. A quad Bolt/barrel upper ran by a single lower would be the best proof of concept. I’d build one but I’m busy!

 

[Gaujo]

Fun. You have me wondering just how many uppers could a single SMG lower operate at the same time?

I wonder if having an additional sear and bolt would be a sticking point legally, even if it were engineerd to only be operated by the primary sear.

 

[rybread]

I wonder if having an additional sear and bolt would be a sticking point legally, even if it were engineerd to only be operated by the primary sear.

That would be the challenge, doing it in an acceptable way- since this theoretical upper would contain the magazine well, sear and recoil mechanism- or several of them. Even as a “closed system” Loading one of the magwells and pulling back the bolt would result in a mag dump. You could maybe avoid that by stacking the channels so the first bolt operated the sear for the adjacent bolt and so on...

Whew that would be a fun project in that it would be challenging, but I’m happy to stick to the simple stuff for now (mechanically & legally speaking).

Shipped parts arrived yesterday. Hopefully I’ll get the plasma cut parts today and my shop part this week, I’d like to do some cutting & welding this weekend. Router assembly was a breeze, I will use the interim time to work on that- I have a Czech military box I’m going to use for this DMAC it’s just the right size so a good first project will be to make some custom notched wood bars for the upper to rest upon.

 

[strobro32]

How about a multi barrel, spring wound, Gatling upper assembly, wear the sear lets her rip. Tim Bixler meets Ingram meets Tippmann Armory

 

[rybread]

I’ll stick with non rotary firearms for now thanks!

No word from the shop but I got router bits and some dremel bits so I can do some part preparations while we wait.

 

[rybread]

I Dremeled out the barrel tube holes in the mounting plate to a tight fit. Got a call that the initial upper housing Assembly is complete so I’ll pick that up AND get my pin back... then I can set this dual upper up for welding.

 

[bigj480]

Fun. You have me wondering just how many uppers could a single SMG lower operate at the same time?

I was thinking the same thing, that brought to mind this creation: http://www.gunsholstersandgear.com/2015/02/25/tromix-siamese-m16/

 

[rybread]

Got the mount & pin, so I can weld these in place.

 

[rybread]

Ya want something done right.. well we took about three steps forward and two half steps back. Picked up the upper housing, and the top cover hinge is misaligned... picked up the plasma cut plates and two of the thin ones are thick and two of the thick ones are thin... parts have been re-cut so I’ll go get them in a bit.

 

[rybread]

Tubes cut, test fitting- you can see the trigger linkage rod & cap- the cap is to be pinned on with a spring under the cap- the mount plate provides the resistance.

 

[rybread]

I like the size as this comes together.

 

[Gaujo]

Dude that looks sick! Why did you need the spacer between the trunion and the allignment tool that requires the thicker material? I had expected a threaded tube that you press the barrel into and use a nut to hold it to the trunion.

 

[rybread]

Thanks, getting there!

The tubes get welded to trunnions, then the mount disk. Just have to wait to attach the lowers, spade grips and front sight plate first - to ensure proper alignment when welding. Those tubes will come forward a bit- the barrel shrouds fit over the portion of the tubes that protrude about an inch from the mounting plate. This way the parts are serviceable- easily taken down to replace a barrel.

 

[rybread]

Sighted. Will start grip assembly tomorrow- hopefully I can get a good start on that, weld those tabs on & up get it up on a mount.

 

[rybread]

Final part submitted for plasma cutting, hopefully the last one on this build! I may try to make a stand in mock up so I can bolt the lowers to it and weld the rest while we wait.

 

[Hood886]

Interested in the plans for this! Looks like a ton of fun!

 

[rybread]

Interested in the plans for this! Looks like a ton of fun!

As with the 12 gauge upper, I will facilitate making this available to the MAC community- these are open threads, and I’ll be happy to provide a parts kit or other details if anyone wants to build their own. For the Dual Mac I’m already building a second unit as I go, though it’s currently paused until the first one is complete, so I can test it and make any applicable upgrades to V 2.0!

 

[rybread]

All right the last piece was expedited- that’s how you do it! Ready to build with all the parts. It’s about to storm here but tomorrow looks good - 20% chance of rain but I see that as an 80% chance I’ll be working and welding- I like those odds.

 

[rybread]

Set up to weld