I want to make a muzzle loading blackpowder 4 gauge shotgun just for fun. I live in the USA, but as far as I know, the ATF does not control firearms that shoot loose powder.

The barrel will be made from 1 inch 304 stainless pipe with an ID of 0.957" and wall thickness of 0.179". The back will be sealed with a plug welded in place. Ignition will be by cap with the nipple adaptor welded to the side of the breech. I will fit it to a homemade stock. I have read online that the nominal load is 4 ounces of shot, and that shot and powder volume should be the same. I do not think I will exceed 3 ounces of shot myself, although I may proof it with up to 6 ounces.

Any suggestions? Thanks.

Ranb

I have done this project. I do have some insightes.



"The barrel will be made from 1 inch 304 stainless pipe with an ID of 0.957" and wall thickness of 0.179"."



You want seamless chrome moly. The wall thickness should be thicker. Mine started out as 3/8" wall. I tapered it on a lathe to reduce weight. You want the weight, recoil it going to be hefty.



"The back will be sealed with a plug welded in place."



Absolutely not!!! It must be threaded and you need a seal on the rear face of the barrel.



Ignition will be by cap with the nipple adaptor welded to the side of the breech.



Wrong again, Thread the drum into the breech plug. You want a tapered recess in the breech plug that is intersected by the drum extension.



Proof charge for a 4 ga is 928 grains powder and 1649 grains bullet, followed by 547 grains powder and 4 2/3 oz shot. Service charge is 273 grains of powder and 3 1/2 oz shot.



You didn't mention the lock. You have to make it. I did all sorts of gyratiuons to try and adapt a brown bess lock. In the end I figured out that the plate needs to be made for a big fat barrel. It will not lay out properly otherwise.





As for suggestions, I suggest you learn more about gunsmithing and muzzleloaders. Make a kit. Scratch build a gun. When you understand how it needs to be done go ahead a make a safe well designed 4-bore. The mickey mouse design suggested above might well get you killed.

Check the latest issue of "Hatari Times" for an article on homemake shotguns. It is interesting.

Neat project.

How'd you come up with the barrel wall thickness?

Steve