Weatherby Tactical Conversion

If nothing else, this project promises to be fun. The plan is to take this Weatherby SA-08 20 gauge shotgun and change it’s role in life from a getting-started bird gun to a home defense tactical shotgun. Yea, for when time, money, and reason aren’t part of the equation.

First up is that barrel. You don’t want to be swinging that thing around in the dark in your house, so it has to come off. The stock barrel is 24 inches, and a quick check with a tape shows that we can take off about 10 inches and put the muzzle right above the sling mount on the magazine tube. That’ll leave just a tad over 14 inches which is pretty decent.

As luck would have it, the cut point for 14.25 inches is still in an attachment block for the rib, so the front of the rib won’t need to have support added. Skipping all the boring details I used a foredom tool and cutting disk to make a rough cut and get the bulk of the barrel off. After that the barrel went into the lathe and a proper end cut along with light chamfering to make things look pretty. The edges on the rib were easy to clean up with hand files. Once all the edges are cleaned up a quick re-blue and it looks like it was meant to be!

This gun is designed to shoot across the living room at the dirtbag halfway in the window so I’m leaning toward not bothering with threading it for a choke, cylinder should be pretty good for 20 feet with buckshot. If it patterns poorly then that’s always an option.

And of course, the requisite NFA markings…

Attachments are a must for a tactical shotgun, a light or laser or something under the front, so we need to add a picatinny rail section to the fore grip. the plastic grip is curved (for your gripping pleasure) so we’ll have to mill out a bit so the rail is lined up with the barrel. Cutting a pair of .118 grooves at .2525 off center will give the rail a comfy notch to fit into. the groves need to get deeper as they go back into the grip to keep the rail parallel to the barrel. Mr. CNC to the rescue.

The grooves will need a little cleanup but cradle the section of rail nicely.

Drill and tap for some retaining screws and it’s ready for a bad guy locator beacon. We might need some additional picatinny on the sides, we’ll see after running it for a bit.

There’s no way you could call this a defense shotgun with the little leaflet charging handle. The factory handle is oddly small, and pointy. A simple round bar would have been far better if you ask me. This needs to be changed. The easy fix would be to use the handle setup from the Moss SA-20 but making one is more fun. The stock handle is a flattened oval shape with a retention detent, and then a stamped finger pain inducing shape on the end.

The starting point for this is some 5/16 steel stock, about half threaded. Once the threads are in place (pretty standard stuff) the remaining shank is turned down to the max width of the factory handle, about .313. a pair of nuts locked together provide a grip surface in the lathe and protect the threads.

A little coarse grinding followed up with progressively finer adjustments and we’ve got the basic shape for the handle.

A round file adds the necessary detent for the retention pin. This will take some more cleanup to get things smooth and polished but it’s good enough for a test fit.

The handle locks in place and runs the carrier as it should. Some of those threads will probably have to come off but as you can imagine it’s a bit harder to add threads than it is to take them off so I opted to go too long instead of too short.

Next up is to turn a custom knob for the new handle. The standard thread will take any number of knobs off the shelf but where’s the fun in that?

Aluminum stock will make a nice lightweight knob. Overall this will add some weight to the carrier so the gas ports might need to open up a bit more. I’ll know for sure at the next function check. Starting with the bar stock, I added knurling to it and then used round cut bits to drop some grip grooves into it. After that just add a radius to each end and all that’s left is drill and tap.

The finished knob installed on the charging handle bar (after removing about a quarter inch of excess threads). P.S., the gun wouldn’t cycle reliably with the extra weight of the knob, so I turned it down about 35%, keeping the same basic design. I chose to turn the knob instead of opening up the gas ports more than I already had.

Next up are the sights. That little bead on the front isn’t going to cut it, especially since it’s on the part of the barrel that’s gone now. I wanted a nice bright sight, good in low light, and with a large ring for fast location. A Truglo turkey sight setup seems perfect for this. A quick drill & tap for a screw will hold the sight in place, but only marginally. A decent side strike can knock it out of place. I milled out a notch in the end of the rib to let the sight retain just a bit better.

The rear sight required milling the sight bracket down to fit inside the grooved top of the receiver. This sight is designed to clamp onto the vent rib but it needs to be further back to get as much sight separation as possible. After cutting the sight base into a tang and putting a couple holes in it, it mates nicely with the matching threaded holes added to the top of the receiver. Use of short screws is necessary to keep from interfering with the carrier.

With both sights mounted, the view from the back is just right. Getting an iPad to focus on the front sight while looking through a ring is an exercise in futility, but you get the idea.