Mounting a 12ga to an AR15

[R3dundantC]

Stupid question time.

I saw some pictures that people have taken 12ga shotguns and mounting them under their AR15. Now, it looks rather unwieldy with a 18inch barrel, so it would work better with something like a Serbu Super Shorty AOW. If you where to take a virgin shotgun reciever and never put any form of buttstock or a vertical foregrip, and keep the barrel at >18 inches, what does it have to be registered as? an SBS, AOW, or DD if at all? And one was to add rifling to the mix?
I poured over the ATF regs and couldn't come up with a conclusive answer. In the end I suspect it would just be easlier to buy a Serbu, pay the $5 transfer, and mount from there.

 

[R3dundantC]

Erp. I just found that this topic is all through the THR archives. I hadn't phrased my searches right. Disregard. I'm going to leave the thing open though for further thoughts and discussions.

 

[Shovelhead]

http://www.thefiringline.com/forums/showthread.php?t=75552

 

[rcmodel]

What in the world for?

Anything the sawed-off shotgun will do, the AR-15 Carbine will do as well, if not better.

Except maybe door breaching.
And most of us don't do much of that.

rc

 

[Shovelhead]

More practical........

 

[mljdeckard]

Here's one practical reason why.

When I shoot coyotes, I often take a rifle and a shotgun. If they are within 40 yards I grab the shotgun. I have thought to myself, I might make life easier if I had both of them together, the transition would be easier. I would not have a short barrel, I would probably have at least a 24" barrel. No point in doing it if I couldn't get some range out of it.

I would also take some guilty pleasure in having one mounted under a dedicated .22lr upper for jackrabbit busting. I switch back and forth a lot between rifle and shotgun for that one too.

So I do some digging on the easiest way to do it, and I see that pretty much all of them have the rear of the receiver squared off, as in the one in the photo above. I suppose I COULD do that myself, but I would probably take it to a machinist or gunsmith. I probably wouldn't buy a new 870 for this, I would get a used one from a pawn shop. Probably the oldest, most hammered one I could find. (A Mossberg wouldn't work very well for this since you couldn't access the safety.) Then, I would look for a two-sided rail adapter, to lock it straight to the bottom rail of the rifle. If I wasn't sure this is secure enough, I would fabricate a bracket to lock between the gas block and the gun barrrel.

Just thinking out loud, and it's WAY down the list.

 

[highorder]

I think Lee Lapin said it best, so I'll paraphrase:

Go grab a 5lb weight and tie it to a string.
Suspend it from your FSB and tell me what you think of the idea then.

When he put it like that, I lost what little interest I had.

 

[w_houle]

More practical........

 

[george d dennis]

sounds like someone likes the look of a m203.

 

[Gunnerpalace]

It looks cool, I want it,

Unfortunately SBR's are illegal in Michigan

 

[Avenger29]

sounds like someone likes the look of a m203.

No, if somebody likes the looks of a M203, they buy a 37mm flaregun that looks like one. The M203 is heavy/bulky enough...and it only weighs three pounds with a length of 15 inches.

And then there is the so called "Masterkey" which is an M4 with an underslung shotgun. I'd definitley get some range time with one before buying and subsequently regretting the purchase...notice it weights 5 3/4 lbs and has a length of 17 inches.

 

[george d dennis]

didnt know anything about a masterkey. all i remember is the m203. and that was
40 yrs ago. goodluck
george

 

[Quiet]

 

[sv51macross]

From what I've read the Masterkey is not the most elegant solution, not only for the weight but also due to the large recoil of the shotgun shells deforming the pin holes on the receivers and damaging the buffer tube mount. (Someone please correct me if my information is false).

It does look cool though.

 

[Kind of Blued]

From what I've read the Masterkey is not the most elegant solution, not only for the weight but also due to the large recoil of the shotgun shells deforming the pin holes on the receivers and damaging the buffer tube mount. (Someone please correct me if my information is false).

Bohica Arms mentioned that their .50 BMG uppers didn't cause considerable damage to AR lowers after thousands of rounds. They're selling a product of course, but if a .50 BMG doesn't kill a lower, a 12 gage shouldn't either.

 

[Quiet]

FYI.
The US Army has dumped the tube-fed pump-action shotgun master key, in favor of magazine fed straight pull bolt-action shotgun master key.

The US Army purchased 38,000 M-26 Modular Weapon Systems to replace the 12 gauge pump-action shotguns being used.