Sunday, May 14, 2017

A Tribute to the Richardson Guerrilla Gun part 1

If you missed the story of the Richardson Guerrilla Gun, see it here

Before we get started with the actual build we should clear up some things. 
First thing: it is perfectly legal to build your own guns in the United long as the gun being built is otherwise legal to own. 
Second, there are a lot of laws and rulings regarding shotguns, how long they need to be in both barrel and over all length, whether or not they ever had a shoulder stock etc...
I am sticking to the classic and safe (legally speaking) definition of a shotgun: equipped with a shoulder stock, barrel of 18" or more with an overall length of 26" or more. 

If you should decide to do this for yourself, be careful, be smart and ALWAYS follow the four rules of gun safety.

For the record, we will be trying to duplicate this gun:

The build is pretty simple, assemble parts and figure a way to attach them to a stock. 
I had been saving this broken Beeman air rifle stock to someday practice checkering on, this will work perfectly for this project.

I didn't know what type of wood the stock was made from, I assumed beech, maple, birch or some other hardwood. On Beeman's website it simply says "European Hardwood", it is definitely not walnut. I do like the reddish brown stain though, I may see if I can find the same color stain. 

The Beeman used a tubular receiver, although of a slightly smaller diameter than what I will be using.

stock photo:

We will be using Schedule 40 black iron pipe for the barrel and receiver. Many people think that this stuff is not strong enough for building a shot gun, but it has been done by hundreds of people and I haven't seen any of them blown up...yet anyway. To be safe I will not be firing anything but low base bird shot.
Please keep this in mind if you decide to build one of these for yourself.

Even though this has been engineered numerous times, I wanted to check the numbers for myself. The 3/4" Schedule 40 pipe has an OD of 1.050, while the 1" pipe has an ID of 1.049, that is pretty close, so some sanding will probably be required to make them fit together


The 3/4" pipe's ID is 0.824" which is a little larger than the SAMMI spec of 0.811" for a 12 gauge Chamber (the OD of the cartridge base is 0.809), but numerous people have used this pipe with acceptable results.

I purchased a 12" piece of 1" Schedule 40 steel pipe and a 24" piece of 3/4" Schedule 40, along with some bolts and nuts to assist with the build.

I cut the 1" diameter 12" piece down to 9.5", to remove the threaded part. The barrel (3/4" diameter) was cut down to 19", just to be safe.


Both pieces needed the weld slag on the inside to be cleaned up

I still have some cleanup to do on the receiver, but the barrel now fits inside

A couple of the things that make this stock perfect for this is the build in recoil lug that will support the rear receiver bolt and the rounded inletted part which almost fits our 1.3" diameter receiver. A little filing and sanding and it should be good to go.

Here is where the stock is broken

We'll add some wood and maybe a cross bolt to fill bottom of the empty area that used to supply clearance for the cocking mechanism.

I had been looking at different ways to build a fixed firing pin. The original Richardson gun had machined a "nipple" into their breech plug.

I found this flywheel puller in my tool box that I hadn't used in ages, I bought it for my Suzuki Quadracer, when I rebuilt the engine. I don't own any quads or motorcycles anymore and these can be had just about anywhere for $10 or so.
The inner bolt, when completely threaded in is just a little bit taller than the bigger bolt. 

The outside of the big bolt is 27mm, the inside diameter of our pipe is 1.049" which is equal to 26.64 mm. A near perfect fit. I'll mate the two and weld the outer bolt to the receiver tube, which will allow me to remove the inner bolt which contains the firing pin, should I ever need to repair/replace it.

Trial fitting the receiver and breech plug/firing pin

We'll notch the area behind the breech plug so the bolt will clear, allowing the receiver to sink all the way into the stock

I found this cut receiver that still had the trigger attached, it came from a JC Higgins bolt action shot gun, it should work perfect for our trigger-safety.

Stay tuned for part 2