Wildcat ?? Rebated rim Chey-Tac

hemiford

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Oct 7, 2013
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266
The thought occurred to me, figured I could inquire here.

C-T cartridges have a rim of about .640-in., I was wondering if anyone
had cut down the rim to .580 or so, which is the Lapua/Rigby boltface.

Like the UltraMags rebated rim.

I think it would be quite a hassle to turn down the rim, and might
have to deepen the extractor groove too.

Just wondering.
 

jfseaman

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Apr 8, 2012
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Location
California Central Coast
Swamplord will hopefully chime in.

The Chey-Tac is based on the 505 Gibbs with the rim full diameter to the base, Cartridges based on the .500 Jefferies rebated rim are what you describe.

Base and shoulder diameters are pretty close with the Jefferies giving up .015 at the base. Length is the major difference in capacity. The Gibbs is 3.150 the Jefferies is 2.750 giving the total capacity edge to the Gibbs designs like the Chey-Tac. This does come at a cost, very long cartridges. After that it depends on what you want to sling down range. Swamploard has the ".375 MJOLNIR" http://www.longrangehunting.com/forums/f19/500-jeffery-based-wildcats-107936/

I have drawn up a .500 Jefferies based design similar to but shorter than Swamplord's. An aside, most of my implementations (actual rifles built/owned) are based on the 404 Jefferies linage like the WSM, Nosler and RUM. I want one .375 and that will be on the .500 Jefferies based designs.
 

MagnumManiac

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Feb 25, 2008
Messages
3,294
The thought occurred to me, figured I could inquire here.

C-T cartridges have a rim of about .640-in., I was wondering if anyone
had cut down the rim to .580 or so, which is the Lapua/Rigby boltface.

Like the UltraMags rebated rim.

I think it would be quite a hassle to turn down the rim, and might
have to deepen the extractor groove too.

Just wondering.

You could quite simply turn the rims down yourself and have the bolt face cut to suit, but there is a big BUT coming. A lot of 500 Jeffrey rifles have trouble grabbing the rim EVERY TIME. It is quite difficult getting a rebated rim of anything more than .010-.015" to feed properly. The other problem, if it's CRF, is timing the extractor bevel. The case rims and extraction groove MUST match for angle and depth.
I researched this to no end before I made my decision on buying the 505 Gibbs, reliability is No.1 in my eyes when it comes to cartridge design.
Even the WSM's/RUM's have had trouble in some rifle designs due to the rebated rim.

Why not start with a rifle action that can handle the case design FIRST?

Cheers.
lightbulb
 

hemiford

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Joined
Oct 7, 2013
Messages
266
MagnumManiac:

"Why not start with a rifle action that can handle the case design FIRST?"

Very common sense, I couldn't agree more.

Just exploring possibilities. I did not know about the rebated rim
feed / extraction difficulties.

On a side note, what do you think of the Montana Rifle Company
PH action ?
 

MagnumManiac

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Joined
Feb 25, 2008
Messages
3,294
MagnumManiac:

"Why not start with a rifle action that can handle the case design FIRST?"

Very common sense, I couldn't agree more.

Just exploring possibilities. I did not know about the rebated rim
feed / extraction difficulties.

On a side note, what do you think of the Montana Rifle Company
PH action ?
Can't say I know a lot about them, I use Rem 700's, Win 70's and just started dabbling with CZ 550 Safari Magnums.
I know that Granite Mountain make a couple of actions that will handle the Gibbs, one is BIG, the other is even BIGGER, bolt diameter is bigger than .750" in the bigger one.

There are other custom actions that will handle the CHEY-TAC/GIBBS sized catridges.
My own 505 Gibbs is a custom shop CZ 550, absolutely stunning rifle, except for the cheap factory cross bolts, I did order the Rechnagel style, but somehow they got ommitted. Will be replacing them myself when I get around to it.

Cheers.
gun)
 

Swamplord

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May 2, 2004
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1,667
Location
Alaska
Regarding the 500 Jeffery .......
The difficulties with extraction were associated with older 500 Jeffery brass that was much thinner in the web area and the cartridge is nearly straight walled, upon firing heavy bullets with hot loads in hot temps .....cases expanded to fill chamber and got "stuck" by over expansion/stress, the rim was basically stripped off by extractor failing to remove spent case,

Using modern brass from Bertram, Norma, Jamison AND applying case taper of at least .015" eliminated any extraction failures with even the hottest loads that bust Jamison brass primer pockets with two firings
 
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