Progress on the AR-pattern blunderbus

[command_liner]

Progress continues slowly on the AR 15 blunderbus.

I picked up an 80% lower to go with the DPMS lower parts kit
and DPMS adjustable stock I got last summer.

Last weekend and the weekend before that good progress was made
on the barrel. It is 1" bore 1 3/4" OD DOM tubing for the main tube,
and 1 3/4" ID tubing with about a 1" wall for the bell. The barrel
was taper bored at the mouth using my longest boring bar. The bell
was welded on, then brazed from the inside. After cooling it was
soft, so it was possible to turn the 3" bell down to about 1 1/2".
The inside of the bell needs to be machined.

The other end will be fitted with a brazed-in 1" plug, then a cap will
be welded over that.

The main lug will be a large block welded to the bottom of the barrel,
extending down the magazine tube. Front and rear AR lugs will be
fitted too.

But how to make it go boom? It is not so simple to fit percussion
caps to a blunderbus operated by the AR trigger system. But I have
time to work on that problem, and I have a few ideas. Think
coach gun exposed hammers operated by 1 trigger.

[POLICESTATE]

Pics! We must have pics!

[adamsreeftank]

Definitely thinking outside the box!

[command_liner]

My son is 7 and likes things that go boom.

We have a few 1-bore black powder cannons, and he has a Henry Mini-bolt.
Bigger than a mini-bolt, but smaller than 1-bore?
A blunderbus seemed like good idea. Using an AR chassis seemed like a
way to save a LOT of time. I am thinking of using Hawken-type screw-in
nipples to save more time.

I have dozens of pictures, but mostly you see machine tools and piles of
swarf. It takes a lot of turning to make a blunderbus out of steel.

[adamsreeftank]

...

I have dozens of pictures, but mostly you see machine tools and piles of
swarf. It takes a lot of turning to make a blunderbus out of steel.

I'm interested in the pics!

[ke6guj]

sounds cool. I'm almost finished on my muzzleloader AR upper. Just need to thread the barrel for the breachplug and then come up with a good way to secure the barrel into the upper.

[five.five-six]

yes!... wait.. is this going to be a DD?

[command_liner]

Is a blunderbus a DD? Not AFAIK.

It is a black powder reproduction. Not a rifle, not a shotgun.
Does not fire fixed ammo -- and that is a key right there.
By starting with an unfinished lower, it never was a rifle, or AOW.
The lower never will be finished to become an AR lower. It is
just a chunk of metal that holds common accessories.

So what we have is a black powder reproduction of a 500 year old
weapon.

All weapons are "destructive devices", but this one does not seem
like a federal felony DD.

[ke6guj]

front stuffers are normally exempt from the DD regs.

[command_liner]

Various photos of recent machining.
A blunderbus is hidden under all that steel. I am trying to get it out.

http://www.flickr.com/photos/command_liner/sets/72157623583216070/

[Noobert]

Are you using the old style 80% lower?

[command_liner]

Are you using the old style 80% lower?

There are lots of different 80% lowers. The one I am using is threaded
for a buffer tube and the fire control pocket is solid. This is perfect for my
application, because my fire control will look nothing like a stock AR.
Ergonomics will be the same, though.

[five.five-six]

Is a blunderbus a DD? Not AFAIK.

It is a black powder reproduction. Not a rifle, not a shotgun.
Does not fire fixed ammo -- and that is a key right there.
By starting with an unfinished lower, it never was a rifle, or AOW.
The lower never will be finished to become an AR lower. It is
just a chunk of metal that holds common accessories.

So what we have is a black powder reproduction of a 500 year old
weapon.

All weapons are "destructive devices", but this one does not seem
like a federal felony DD.

AFAIK, all 12 gauge shotguns are "DDs" for being over 1/2 inch, they get a special exemption ... I suspect the black powder part would make it not a DD, however I still want to see pics

[xxdabroxx]

Looks really good, please post more pictures as it progresses.

[command_liner]

Tonight we machined the profile for the barrel near the combustion end.
Length of the taper determined by the travel of the cross slide.