Some years ago, there was someone or two building double rifles from shotgun actions - CZ, I believe. My recollection is that they were pretty affordable, as doubles go. Is anyone out there still doing this?

A while back I looked into having some barrels made for a Win M21 and never got a complete answer as to why a set of barrels couldn't be made that would fit the action. All wanted to cut the barrel portion of the "upper" off, then attach some rifle barrels to "the bloc", to then fit on the action. Doing so meant that I would lose the shotgun in exchange for a double rifle of questionable utility and value. What I wanted was to have a M21 that had a set of shotgun barrels and another set of rifle barrels that could interchange. For some reason, this is not possible.

A second set of barrels...using the SAME forened is a huge lot of work. As is aligning the striker holes in the action with the centre of the chambers.

Yes it can be done bt FWIW I'd reckon you are cheaper just to buy a second Winchester and make that as a dedicated DR.

Trust me on that. The cheapest option might be an old Baikal O/U that came as a combo with 29" barrels and 26" skeet barrels and just cut them.

There are quite a few such gun makers in the US.
One or more may see this post and comment later.

I have made six DRs on shotgun frames. And Butch Searcy started out making them on Brownings. As long as you know how strong the frame is before you start, it is, not easy, but straightforward. For example, do not make one on an old US shotgun with an iron frame. I use only those with a known proof history, and the Germans and Russians are the highest proofs I have found. Then, calculate the back thrust of the cartridge you want to use. Because this is the most important thing; not the barrel (hoop/radial) strength. Modern chrome moly steels make it easy for us.
Back thrust is calculated using the Inside of the case, not the outside. Pressure does not act on the outside. Surface area times chamber pressure. Compare that to the proof of the frame, and the back thrust of the gauge your donor shotgun is. Not the pressure, of course, a 12 ga has a lot less pressure than a 450 Nitro. But we don't care about radial pressure. Ok, we care, but you get the picture. Mono blocking the barrels into the existing block is easiest but there are other ways. That insures firing pin alignment.
Anyway, get Brown's book and he will tell you about it; I was doing it before there was a book though. Lot of work.
Ray,. what you wanted is entirely possible, but more work and skill (and time) required than 99% of even good gunsmiths have.

quote:

What I wanted was to have a M21 that had a set of shotgun barrels and another set of rifle barrels that could interchange. For some reason, this is not possible.

No. It is possible and I have done it. However it was with another action (SLE) just as strong (in my opinion) as the M21. It must be noted that you are not going to like the price to do it; and secondly ordinary gun "tinkers" do not know how to do it/have the equipment to do it. I displayed photos on this website on how to do it. Search this site they may still be there--the caliber is .38-55 McPherson.

Aaron Little, of course!

As noted by several, the reason I abandoned the effort to get a second set of barrels was that I would be money and time ahead to keep the M21 as is and get a complete double rifle. the only problem with that is every time I start looking at them, there is another just a little bit more money that I like better; so at present I'm just seeing if I can save up enough for a Heym.

quote:

Originally posted by Steve up North:
Some years ago, there was someone or two building double rifles from shotgun actions - CZ, I believe. My recollection is that they were pretty affordable, as doubles go. Is anyone out there still doing this?

Look here:

http://forums.accuratereloadin...0101804/m/3141016532

and here:

http://forums.accuratereloadin...0101804/m/9561066812

Clark Custom Guns was doing a conversion on CZ's. Looks like maybe he stopped doing it now though.

I picked up a used 450NE made by Gordon Harms on a Huglu. I gave 4K for it in 2012. I've shot it a bunch and took a Buff in Zim. I'm happy with it. Since got the bug and bought a few more doubles. But that conversion is a work horse and no fear to hunt it hard as opposed to the higher dollar guns.

Correct me if I'm wrong , but weren't all the California Rigby's built on shotgun actions ???

Slight additional information on bolt thrust...

Bolt thrust CAN ALSO be calculated by using the area of the case head as a practical matter by using the Area of a Circle formula,
A = Pi x radius squared, 3.1415 x r squared or A = 0.7854 x diameter squared.

Much simpler that calculating the inside area of the case head(which is a bit smaller than the external measurement)and doing a BUNCH of math or you're in to Finite Element calculations...

Dan Lilja has written a nice tome on bolt lug strength and VarmintAl added a Finite Element GW BASIC program for those interested in playing with numbers and old code.

See Wiki "bolt thrust"...and a nice picture and explanation of what's going on.

Good Hunting

quote:

Originally posted by 209jones:
Clark Custom Guns was doing a conversion on CZ's. Looks like maybe he stopped doing it now though.

Thanks for all the input and suggestions.

Clark's site looks as if they no longer do those conversions but I should call them. I have a medium double - a Zoli O/U in 9.3x74R. I am not looking for a heavy double but the opposite end of the spectrum - a light double. Something rimmed, on the order of 30-40 or thereabouts.

quote:

Originally posted by sjr:
Correct me if I'm wrong , but weren't all the California Rigby's built on shotgun actions ???

You are correct, sort of! Merkel double barreled shotguns are made on double rifle actions, not the other way round!
The California Rigbys WERE made on Merkel actions, but that was not their downfall. The regulation, was sub standard in those Cal Rigbys! That and the price is the reason they failed.
The "STRONGEST PART" of the Cal rigbys was the Merkel action!

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Most people know that I started using the BSS Browning shotgun actions for double rifle conversions. Reason for this post is to remind all that there wasn't a conversion on a BSS action that I didn't reheat treat it. Most shotgun actions are way to soft for rifle cartridges.
I had the BSS action analyzed so that I could heat treat it properly.

Ok, the bolt thrust is not affected by the OD of the case head. The internal pressure does not know, or care, how big or small the case head is. If that were the case, all we need to do is use a rebated head cartridge to insure minimum back thrust, which is ridiculous.
The internal case pressure can and does, only act on the Internal area of the case. Nothing else.
So, when you do the formula for back thrust, use the internal area. Brass adhesion to the chamber wall reduces that a lot, but for the maximin result, just go with that. It is not the OD of the case. If you use the OD of the case head, then you get a higher number, of course, which is ok, Just not the correct number.

Sorry

As a PRACTICAL calculation...to give a safe and quickly calculated number to see if things are starting to get outta hand...not trying to get a hoohaw going or get into minutia. I've been using that formula a long time and it was given to me by a REAL, long dead, old timey experimenting gunsmith when I was helping him blow up M98's...HE was the engineering mathematician...I didn't get into the science of it for many more years, nor how to manipulate formulas to make things a bit easier...

Internal pressure acts on the internal area, true, which is THEN transferred to the exterior case area through the brass...otherwise we would NEVER have to resize cases.

Pressure is equal and uniform over the entire interior of the case which is transferred through the brass to the exterior of the case which is then transferred to the chamber walls, and also the bullet base and case head.

Axial and radial pressure, not quite simultaneously, but for intents and purposes and practical purposes, in milliseconds, if not nano seconds is readily calculated...I'm certain there is a "punch in the number and hit enter" program available somewhere that doesn't require an Engineering/Physics/Mathematical PhD to use, that will give all the information required to calculate those parameters...for those few interested.

I was just pointing out WHERE to read up on the math for those interested...all this "stuff" is/has been done and is available online, again, for those interested...the numbers are crunched and readily available to peruse...the BAD thing about it is someone will misuse the data and get ****ed up, I'm sure of it.

Good Hunting

I don't consider that simple principle minutia; it is just the way pressure physics works. But of course, anyone is free to calculate it however they like.

Also the shape of the cartridge case will retard or exacerbate the reverse thrust of the cartridge against the bolt or breach face of a double. This was solved by P.O. Ackley with his Ackley improved cartridges like the 30-30 Ackley improved.

The way it worked was the longer flat walls of the case grabbed the walls of the barrel chamber reducing the reverse thrust upon firing.

The recoil lugs where removed from a mod 94 Winchester 30-30 re-chambered for the AIM case with hot loads and fired in a fixture to hold the rifle, and it didn't even push the bolt back with a load the was considered way too hot for a 30-30 Win 94 in a factory case shape.

These Ackley Improved cartridges are a good design for double rifles as well to modify the reverse thrust.
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Absolutely; I have been trying to tell people that for years and no one believes me. Brass case adhesion to the chamber is important. And some guys want to actually grease their brass before firing!

Steve, I was having Aaron Little put a set of 450-400 barrels on a McCririck 16 bore hammer gun for a 2 barrel option. BPE of course. However, I purchased an Atkin 450 BPE from Holts rather cheaply. The bores weren't really that good and, instead of re-regulating the Atkin, I had him put the 40 caliber barrels on the Atkin and refinish it. To answer your question yes, it can be done.

Thanks for all the information. I appreciate the responses.

I like this topic..here's a LC Smith FWE 20 ga, I did a conversion. Found a set of rough barrels, and mono blocked to 45-70. The tool is an enhanced version of the original LC Smith TD tool. Shot one Axis with it.

quote:

Originally posted by Duane Wiebe (CG&R):
I like this topic..here's a LC Smith FWE 20 ga, I did a conversion. Found a set of rough barrels, and mono blocked to 45-70. The tool is an enhanced version of the original LC Smith TD tool. Shot one Axis with it.

Always wanted a 45-70 in a DR,what load did you regulate the gun with?