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I have wanted a double rifle since I was a teenager. I only ever saw them in movies and in the Gun Digest price guide and always drooled over them. However, due to the price and the impractical calibers theyre chambered in, owning one was always just a pipe dream.
A few months ago I found out that a guy can build a double rifle from a shotgun and that got the gears turning. I started researching. I read forums, watched YouTube videos, and bought and read Ellis Browns book. I THINK I posses most of the skills necessary to pull it off. I am a fabrication engineer now (self taught) but I started as a metal fabricator and did my vocational training in high school in machining....which I still dabble with. I do have access to a mill and a lathe at work and I have a couple of friends that are pretty accomplished career machinists if I need some help. Im learning the knowledge, I have most of the tools, all that was left was choosing a caliber and finding a donor gun to hack up.
I knew that whatever caliber I chose, wasnt going to be an African safari round. I would serve me almost zero purpose in southern Michigan, which used to be a shotgun-only zone for big game hunting...but like many other Midwestern states, about a decade or so ago they legalized the use of certain straight wall rifle cartridges. The caveat being that the case length had to be between 1.16" and 1.80" so that limits my possibilities ALMOST exclusively to pistol rounds.....almost. Some states allow the .45-70, .38-55, .444/.450 Marlin, etc but theyre all too long to use in Michigan, (southern Michigan, I mean. Up north you can use whatever you want) in fact, I just had a Marlin 1895 .444 rechambered to .445 Super Mag so I could legally hunt with it but thats beside the point. The point is, if Im going to put all the time, effort, and money into building a double rifle, its not going to be a safe-queen. It had to be something I could use. A guy I have been in contact with that lives out west, just developed a Michigan-compliant round based on the .45-70. The case was shortened to 1.8" and he loads it with a faster burning powder. In testing he found that it maintained all the ballistics (energy and velocity) of the factory .45-70 without raising the chamber pressure...much. I think he said he calculated the pressure at around 32K PSI. He calls it the .458 Thor Hammer (he named it right after the .360 Buckhammer was released, LOL). So thats it. Thats the caliber Im going with. I reached out to Pacific Tool and Gauge and they are in the process of building me a chamber reamer. I also reached out to Lee Precision to have custom loading dies made.
Now I need a gun. I had a pretty good list of boxes that would need to be checked if a shotgun was going to make a decent (and safe) rifle. In my research I found that it had to have a double underbite and some sort of a third lockup, Greener crossbolt being ideal but at least a dolls head or a concealed fastener if nothing else. It had to be nitro-proofed, it had to have striker bushings. A few boxes I added that were more personal preference than anything was that it had to have a pistol grip (pommel grip) stock with a cheek piece. It had to have engraving, and it had to be under $1000. I originally thought it had to have ejectors too but ejectors and extractors both have their pros and cons and I wasnt going to let that be a deal-breaker. I did find out that the Bnro ZP47s checked nearly all the boxes...and I did find a couple, they just looked really bland to me....but thats the route I was going to go, Id just teach myself how to engrave. LOL.
Then I found a Greifelt 16ga. Now THAT was a cool looking gun. It checked all the boxes except one, it didnt have striker bushings. On the plus side, the firing pins arent ridiculously large like I have seen on some shotguns, I have heard of guys using the factory shotgun pins on rifle primers without any issues....but there is also a chapter in the book about how to make and install them, so I didnt let that sway me from buying it. It was nitro proofed, it had a Greener crossbolt, a decently gusseted frame, the breech wings are a nice touch, and I loved the engraving on it. Some really nice shotguns have pheasants and rabbits and stuff on them. Which wont work for a big game rifle, but this one is just.....nice. I dont know how else to put it. Another plus was that I was kind of trying to stay away from Spanish guns (per the advice from Aaron Little, a gunsmith that has done more than a few of these), I wanted one that was made in Belgium, Czechoslovakia, or Germany...and this one was made in Germany.
So I guess thats it. Time to roll up the sleeves and get the hacksaw out. Wish me luck.
I do welcome advice and tips and from others with experience. Tell me those things you wish you would have known the first time you did a conversion....because I already have an idea on what caliber I want the next one to be. *wink*

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