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Double Rifles, Single Shots & Combinations >> Paradox and Bore Guns

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casper50
.400 member

Reged: 18/10/07
Posts: 1346
Loc: Alaska

Chamber specs for a 12 bore rifle
#218882 - 02/11/12 11:40 PM

I'm in the process of having a 12 bore Jeffery single rebarreled to a 12 bore rifle. I wish to use brass cases shooting bullet style projectiles not ball. The bore of the blank measures .729 top of land and .732 bottom of groove. Can someone measure the inside diameter of a Magtec brass case? Thanks.

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gungadoug
.333 member

Reged: 13/08/12
Posts: 285
Loc: NM

Re: Chamber specs for a 12 bore rifle [Re: casper50]
#218886 - 03/11/12 01:35 AM

I have a Greener Martini in 12 bore rifle, and had to have a sizing die built to hold the .732 dia bullet- Fosbery style. This die sized down about 1/4" of the case neck to hold and center the bullet. BTW, if you are interested, the fella that made the mould still has the cherry, and could likely build you one as well. If interested, PM me and I will dig out that info for you. I have good luck using Universal Clays.
Thanks, Doug

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DarylS
.700 member

Reged: 10/08/05
Posts: 26537
Loc: Beautiful British Columbia, Ca...

Re: Chamber specs for a 12 bore rifle [Re: gungadoug]
#218897 - 03/11/12 04:33 AM

Doug - how much too large were the unfired cases?

The 16 bore actually hold a 13 bore ball, they are that much oversize, ie: .043" . I'd think the 12's would hold an 11 bore (.751")or maybe almost a 10 bore ball (.774") - perhaps.

--------------------
Daryl

"a gun without hammers is like a Spaniel without ears" King George V

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rglenz
.300 member

Reged: 14/03/08
Posts: 134
Loc: w. Minn

Re: Chamber specs for a 12 bore rifle [Re: DarylS]
#218909 - 03/11/12 06:34 AM

Mike,just measured a new magtech with a plug gauge,.768 inside.You will have to use thick turned brass,or paper with your bore.I guess it might work to size the neck down like rifle brass,I haven't tried it.

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casper50
.400 member

Reged: 18/10/07
Posts: 1346
Loc: Alaska

Re: Chamber specs for a 12 bore rifle [Re: rglenz]
#218910 - 03/11/12 06:48 AM

Thanks Rglenz. That helps alot.

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tinker
.416 member

Reged: 12/03/05
Posts: 4835
Loc: Nevada

Re: Chamber specs for a 12 bore rifle [Re: casper50]
#218919 - 03/11/12 08:33 AM

I have necked and modified magtech brass.
If your're ok with making special dies and fiddling with the relatively thin and fragile cases go for it. Otherwise you'd be really well served with a special set of Rocky Mountain Cartridge brass cases.
I feel that they will be very much worth the cost and wait.

Cheers
Tinker

--------------------
--Self-Appointed Colonel, DRSS--

"It IS a dangerous game, and so named for a reason, and you can't play from the keyboard. " --Some Old Texan...

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DarylS
.700 member

Reged: 10/08/05
Posts: 26537
Loc: Beautiful British Columbia, Ca...

Re: Chamber specs for a 12 bore rifle [Re: tinker]
#218920 - 03/11/12 09:01 AM

Casper- you might be able to get the brass tubing that has a .0075" wall, .015" total. The tubing I'm thinking about is the fit together tubing available at many hobby stores - each subsequent size is therefore .015" smaller than the other, so they slide together.

With this sizing, there are standard sizes, so there should be a .750" outside diameter. The next size up, ie: .765" OD could be used as a liner, along with the .750", inside it- after annealing. Then, once fire formed the ID would be approximately .738" (.768" - .030" + or - a few thou). The actual diameters would only show after forming.

Just an idea. I thought the brass might be a better idea than a thin card liner or attempting to size the cases so far down just to hold a bullet or ball.

Perhaps a Paper case would be perfect?

--------------------
Daryl

"a gun without hammers is like a Spaniel without ears" King George V

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gungadoug
.333 member

Reged: 13/08/12
Posts: 285
Loc: NM

Re: Chamber specs for a 12 bore rifle [Re: DarylS]
#219001 - 04/11/12 10:16 AM

PM sent--
Doug

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