Shotgun insert

[Leeroy151]

Hi,
My name is Lee. I am new to Cast Bullits. Just wanted to get involved in
This forum. I like reloading and bullet casting. I am getting more interested
In wildcatting a cartridge and I need some help please. I am looking for help with a .338 caliber barrel to be turned to fit a 12 gauge break open shotgun. I Can chamber it myself. Any help would be appreciated. Thanks.

[Oily]

Great to have you on the sight Lee. A lot of knowledge here. So I will start out with why? The cost of turning a barrel to fit in a 12 gauge barrel is prohibitive and then you have to add sights or a scope mount. Why not get a Savage action which uses a barrel nut and you can get any barrel or caliber you want and headspace it yourself. And you can switch calibers or barrels anytime you like. And why .338 ? 35 caliber barrels are more prevalent and molds are more readily available. To each his own build what you want. Check prices on what you want to build and weigh your options

[Echo]

Great to have you on the sight Lee. A lot of knowledge here. So I will start out with why? The cost of turning a barrel to fit in a 12 gauge barrel is prohibitive and then you have to add sights or a scope mount. Why not get a Savage action which uses a barrel nut and you can get any barrel or caliber you want and headspace it yourself. And you can switch calibers or barrels anytime you like. And why .338 ? 35 caliber barrels are more prevalent and molds are more readily available. To each his own build what you want. Check prices on what you want to build and weigh your options

Plus One...

[303Guy]

Welcome aboard Leeroy.

I'm with Leeroy. I want to do the same thing but my preference would be something based on the 303 Brit case, like a 40 or even 44. Then again, I have a 410 single barrel that is sitting there calling for an insert of some kind. I do have a few 22lr barrels lying around but I'm not so keen to cast that tiny. Remember this is about fun, not practicality.

I was thinking on setting the insert on "O" rings, possibly several down the length of the insert to minimise movement. Such "O" rings would need to be very thin and pretty tight so good lube would be needed to get the insert out with reasonable effort.

Then comes the question of how to eject the fired case. Well, one could cut an extractor groove and use a manual tool to pull the cases out. In the case of a 12ga shotgun insert there could be room to fit a spring loaded ejector in the insert wall if the case head was small enough and a straight wall case would fit the bill, specially with a 338 caliber. My 410 insert is getting a bit small to do that though although something like a 22 hornet would leave enough room but still, the available space is so small.

Just an idea, one could conceivably fit an extractor powered by the existing extractor. And just a question, what case are you intending using? I assume cast boolits ... naturally.

Leeroy, you might start a separate thread in Special Projects on this. Or maybe ask the mods to move this thread there but here there would be a lot of exposure.

[Leeroy151]

Hi y'all,
What I had in mind was something along the lines of taking a 357 Remington max and necking it to .337 lead bullets for starters. Maybe get a 175 grain bullet going 1500 to 1900 fps. So far I have been using a 38 special insert for a H&R break open 12 gauge. I was thinking a .338 barrel, initially chambered using a .357 magnum reamer, then .338 throater. Use the 357 rem max brass. I took .308 Lee double mold and on one side I drilled out a driving band with an 8.6 mm drill bit. So, it's roughly .337, with a step down to .308 toward the bullet tip. It is about 175 grains of lead.
I use the 38 special insert and paper patch to .357 and accuracy is not so great. 9 inch MOA...funny huh? I use a flash light mount on the barrel of shotgun and a long eye relief pistol scope, x4. I would like more powder capacity than 38 special.

[Leeroy151]

This is .311 paper patched and 38 special case.

[Tatume]

Is your insert intended to be removable, thus restoring the gun to a shotgun? Or are you planning to make a permanent modification? If the latter, then I would recommend the stub method. Cut the shotgun barrel off, thread the stub that remains, thread your 338 barrel, and screw it into the stub. There is a lot of information on the details of the procedure in the Single Shot Guns section of this forum.

[Leeroy151]

Hi,
I was keeping the insert removable. I didn't know about the stub technique. I am trying to make a personalized cartridge, and I was using the shotgun insert as a means to get there. It seems to be a reasonable way to experiment with wildcatting a cartridge. I am interested in straight wall rimmed cases that are to be necked down just a few thousands. This cartridge would be .337 LEEroy. Parent case 357 Rem Max. Necked to .338 and a brush gun. Night gun with a better scope and a lazer? Fun gun with no special purpose? Possibly wind up with a 10 inch barrel and pistol grip with long eye relief scope.
22 charger, something like this, but bigger caliber?

[Leeroy151]

Here is the initial set up. 38 special insert into 12 gauge.

[Jack Stanley]

Just because you want to sounds good enough for me . Fun to play with at any rate .

Jack

[Gtek]

It is great to see the thought and energy put into something different, my self wondering into the what if zone often. After reading several times to make kind of sure before I threw the cold water. My first concern post reading was chamber pressure "Maybe get a 175 grain bullet going 1500 to 1900 fps. So far I have been using a 38 special insert for a H&R break open 12 gauge". What PSI do you think that round would produce? We have no way of knowing without test but I would suspect in the the thirties as a low. Cast single poke receivers may not live with that very long exceeding there 12-14K design range. Hate to see anyone hurt chasing his thoughts, maybe find you an SB-2 receiver or the Savage approach. I may be a worry wart but I have experienced shrapnel, it will change your life in one way or another. Just please be safe and think out before pull.

[Leeroy151]

Yes sir Mr. Gtek,
Dang high pressures there. I nabbed this off the Hodgon reload site:

BULLET WEIGHT180 GR. FMJ
ManufacturerWinchester
Powder296
Bullet Diameter.358"
C.O.L.1.990"
Starting Load
Grains
Velocity (ft/s)
Pressure
Maximum Load
Grains19.0
Velocity (ft/s)1,670
Pressure46,900 CUP

Probably gonna approach 50k if I get too frisky with the fps. It would suck to mess up my pretty face. May hide behind the truck with a 10 foot trigger pull rope. I am thinking lighter .338 caliber projectiles. Thanks!

[P Flados]

You photo in post 8 shows a break open pistol.

I am not sure what the BATF says about going from a shotgun to a rifled pistol.

They would most certianly not like it if simple removal of the insert would easily put you back into underlength shotgun.

As such any "playing" with an insert would need to be done with:

- A barrel length of at least 18 inches and an overall length of at least 26 inches.

I do happen to have a 338 barrel that came in a batch of pulls/seconds and I do happen to have a mini lathe.

However I have not done any barrel turning yet & do not think I am ready to try to making anything where we would have to work out the close tolerances for an insert to fit your gun and then have to pack & ship.

[Leeroy151]

Yes sir, no BATF rule breaking. I was just thinking about making a cartridge that could be used in a 10 inch pistol, if it could morph into that one day.

[Leeroy151]

Here's that modified .308 mold up to the driving band of about .337 by using a 8.6 mm drill bit to fatten up the mold.

[Leeroy151]

https://www.lehighdefense.com/pages/...mmo-technology

Check out the video of the clay block.

[303Guy]

Don't forget that it's not so much the pressure in the breach as the load on the breech face. A smaller case head will require a lot more pressure to produce the same load a shotshell would. Just to keep things in perspective.

Remember the old double combination guns? I've handled a shotgun-577/450. Not sure what pressure the 577/450 produces.

[NoZombies]

Good luck with the cartridge. I don't have a lot of input on that front, If you like it and can do it safely, do it and enjoy it.

I will toss in a few things to consider:

Breach fast thrust, hoop strength, and firing pin diameter are gonna be the things for you to consider. An insert inside a 12Ga barrel will suffer from poor hoop strength due to the small barrel diameter. I've also never had good luck with accuracy from inserts, with 6" at 50 yds being pretty 'good' for most inserts I've tried. A standard 12 gauge H&R (or whatever) frame is going to have a fairly large shotgun firing pin, and will allow primers to pierce and flow back. And the soft Iron frame of most shotguns is a little on the weak side for pressures in the realm you're talking about.

An SB2 frame can generally be had relatively cheaply, and would take care of the firing pin size, and soft frame (breach face thrust) problems, leaving you only the issue of having poor hoop strength. Stub the barrel properly, and that issue goes away, and then you find yourself able to safely play in the pressure ranges you're wanting to without risking your eyes or fingers, and you'll probably find better accuracy as well.

As for making a pistol, in the US, it's illegal to make a handgun out of anything that started as a long gun (rifle or shotgun) without a $200 tax stamp. By the time you would be done paying for the tax stamp, barrel, and other stuff, you would probably be better off buying a contender pistol frame, and getting MGM or Bullberry to make you a .338 barrel that you could chamber as you pleased. Not saying that's the only way to go, but I'd at least look into it.

[Leeroy151]

Thanks guys,
Lots of great advice here, glad I found y'all. I am gonna keep the fps down and the bullets light for now. Lehigh makes a 103 grain .338 projectile. Gonna stick with 18 inch barrel for now. Probably try the SB2 or a savage set up as I can find those. I wasn't much interested in making or remodeling a firearm as I am in developing a cartridge. Thanks again.
Lee

[303Guy]

The insert wall thickness would be nearly 6mm thick for a 357 maximum case which would be the thinnest section. So I would think the pressure limitation would be the firing pin.