12 ga upper for M-11/9 project

[rybread]

In the tradition of this forum, if you can't find one, build one. I know a few others are interested so feel free to share ideas.. this will be an open thread, so if it works it will be a how to for the benefit of Mac owners everywhere.. I've had some ideas knocking around for a while- right now I think my best bet is to effectively convert a Saiga 12 into a MAC upper. So- do I keep the rotating bolt? Do I forge a new 12 ga open bolt (leaning this way)?? Other ideas, thoughts, risks? Not intended for commercial production but maybe one day Richard can take some learnings from this hint hint..

[SecondAmend]

FWIW, back in the 1970s, Max Atchisson experimented with an open bolt, full auto shotgun, the initial AA 12. See, for example, U.S. Patent No. 4,654,993 as a starting point. He and others improved on the design which included changing the AA-12 from blowback- to gas-operated with a locked breech. See more discussion here: https://en.wikipedia.org/wiki/Atchisson_Assault_Shotgun

I'd suggest that you learn from others ('stand on the shoulders of giants', as the saying goes), but feel free to do whatever your heart desires; and best of luck with your project.

MHO, YMMV, etc.

[nklf]

I would think keeping the rotating bolt would be the easiest. It should work just like the Sabre assuming bolt would maintain enough inertia to detonate the primer. Given the energy needed to chamber a round, it may not be that simple.

[rybread]

I would think keeping the rotating bolt would be the easiest. It should work just like the Sabre assuming bolt would maintain enough inertia to detonate the primer. Given the energy needed to chamber a round, it may not be that simple.

Thanks that was the initial approach but as I thought it through, I thought an open bolt may be more feasible with my meager manaufacturing capabilities.

Second thanks I am familiar w the AA and have reviewed the available materials. As indicated this is going to be a garage build, so we're only looking to meet the minimum requirements!

[Battering ram NIB]

video....legal ones exist!!


https://www.youtube.com/watch?v=Vo5gvgRDmsg

need to plan on shorty 12 gauge shells for sure

or shoot clouds

[IndustrialRescue]

Jesus. This is awesome.

[rybread]

need to plan on shorty 12 gauge shells for sure

or shoot clouds

Shorty to start for sure. Also, this will be vehicle mounted. I have a shield mount for my 1919-ish gun.. An extra 90 pounds should help tame it.

[100 bullets]

I've seen that video before, I believe the shooter is not the owner due to his facial reaction afterwards and people laughing in the background. Maybe the gun is more controllable with a different operator, I wished they had more than one person shooting the gun.

[theduke]

you have the attention of many here.

this 1919ish clue has my mind spinning.....

tell us more ...........please.

dan in Oregon

[DistalRadius]

FYI, I think a mini-shell upper could be made direct blowback, similar to a Max-31. Steel saiga mags exist, so there is that avenue if modding is needed. A full size shotgun upper will require some kind of locking mech. Converting an existing Sabre would be the simplest route unfortunately there is no AR-BCG-compatible 12-gauge bolt that I am aware of. And you would have to fab a barrel. Adapting a Saiga-12 to open bolt operation would be no small task but definitely do-able with enough effort.

Seems tricky.

[Starvingboy]

... or go belt fed. 12gauge and 50bmg are the same diameter. Use a cloth belt and skip the magazine

[sniperdoc]

1) Ideally, use the Saiga bolt with a second spring and retainer for the firing pin (the bolt would close first, then "trip" the firing pin, eliminating the inertia problem and also slowing the ROF). This may require a custom firing pin, but AK type pins are easy enough to make.
2) There are drum mags (20RDS, IIRC) available for the Saiga. Expensive, but more fun than the stick mags, and no conversion work to use belts.

[Beowulf]

You need to be careful on how you proceed, if you want to "start with a Saiga". If you want it to be an actual upper and not create a new Post-sample non-transferable, you can't start with a title 1 firearm receiver. It will run into the same problem as the XMG and a few other uppers that were re-classified as post-samples if you put them on a full auto receiver.

If you want something vehicle mounted, you could try something like this guy did:

https://www.youtube.com/watch?v=iX7vwivR6cE

[rybread]

you have the attention of many here.

this 1919ish clue has my mind spinning.....

tell us more ...........please.

dan in Oregon

The 1919 was just in reference to the FN32, which the shield mount is for- HOWEVER, for various reasons I have considered a "cover" for this thing that would mimic that type of set up (since it would use the same tripod interface). It would add weight and enhance safety. Something similar to the .40 upper I'm currently working on now would be ideal- on the scale of a 1919!

[rybread]

... or go belt fed. 12gauge and 50bmg are the same diameter. Use a cloth belt and skip the magazine

This is interesting- great thinking. I'm wondering if that belt fed 12 ga for the RR uses .50 parts as well- that might be even better. That merits some research.

[bigj480]

I try not to be overly negative about these things but...I will just say that if you pull it off I will be surprised and impressed. Things like this basically never get off the ground. I agree with DistalRadius that a HIGHLY modified MAX-31 shooting mini shells would be the best place to start. To me it's actually much cooler to shoot the mini shells full auto since I have yet to see that done and it would be much more controllable. Not to mention just being much easier to accomplish. I don't know how heavy the bolt would have to be but you have room in the MAX-31 to probably make it heavy enough. The way you are planning to go with Saiga 12 parts means that it will be a very complicated system, less likely to work and is almost certain to be classified as a newly manufactured machine gun and thus not usable by 99% of m11 owners.

FORGING a new bolt??? Just no.
A mounted shotgun? Meh.
Belt fed shotgun? You are setting yourself up for failure.
KISS principle FTW, go with the MAX-31/mini shells. JMHO

[sniperdoc]

You'd have to replace the receiver with some sort of "parts holding device" that ATF would approve.

Changing from mag fed to belt fed could be done, but it would take lots of parts (driving costs up considerably), and top notch gunsmithing skills, definitely beyond my mediocre skills!

However, a FA Belt Fed Vehicle Mounted MAC/Saiga Hybrid would be Ultra Sweet!

[rybread]

You need to be careful on how you proceed, if you want to "start with a Saiga". If you want it to be an actual upper and not create a new Post-sample non-transferable, you can't start with a title 1 firearm receiver. It will run into the same problem as the XMG and a few other uppers that were re-classified as post-samples if you put them on a full auto receiver.

If you want something vehicle mounted, you could try something like this guy did:

https://www.youtube.com/watch?v=iX7vwivR6cE

That's kinda barn mounted! Good advice- I'll use some of the Saiga parts but the "body" of the upper will be made new.

[rybread]

I try not to be overly negative about these things but...I will just say that if you pull it off I will be surprised and impressed. Things like this basically never get off the ground. I agree with DistalRadius that a HIGHLY modified MAX-31 shooting mini shells would be the best place to start. To me it's actually much cooler to shoot the mini shells full auto since I have yet to see that done and it would be much more controllable. Not to mention just being much easier to accomplish. I don't know how heavy the bolt would have to be but you have room in the MAX-31 to probably make it heavy enough. The way you are planning to go with Saiga 12 parts means that it will be a very complicated system, less likely to work and is almost certain to be classified as a newly manufactured machine gun and thus not usable by 99% of m11 owners.

FORGING a new bolt??? Just no.
A mounted shotgun? Meh.
Belt fed shotgun? You are setting yourself up for failure.
KISS principle FTW, go with the MAX-31/mini shells. JMHO

All reasonable, I tend to agree with most of it- I'll be surprised if I pull it off! KISS is right- a new upper "shell" using Saiga pattern & parts, open bolt.

[Concorde]

Saiga postie select-fire/full auto:
https://www.youtube.com/watch?v=HR8tvOzYNVk