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Hi m4220,

Page 216 of Speed's 'Original Oberndorf Sporting Rifles" reads "By 1905 Rigby had designed a new .350 rimless cartridge, and some rifles were made up on the step-down receiver ring actions with slanted magazine box, which worked perfectly even with the rimless shells. Later a new Square Bridge action with normal front ring was developed."

I have a photocopy of a photocopy of the original Rigby ledger from J. Roberts & Son showing Rigby originally sold the rifle as a .350 Magnum Mar 23rd, 1910.

I assume the .350 Magnum means the .350 Rigby rimless cartridge, unless Rigby used this designation to mean both the .350 Rigby rimless and the .350 Rigby No 2; otherwise, I'm sure this rifle is one of these step-down receiver ring actions with slanted magazine box chambered in the .350 rimless cartridge.

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Jim,
Saw you broke the extractor upon 1st firing, have you cast the chamber to determine which case your rifle was built for or if the chamber was recut for the rimless case & extractor reshaped at that time? I measured both case types, 400/350= Rim dia. .525, Head dia. .470. 350 Magnum= Rim dia. .525, Extractor groove dia. .450, Head dia. .515.
Speeds book states
"By 1905 Rigby had designed a new .350 rimless cartridge, and some rifles were made up on the step-down receiver ring actions with slanted magazine box, which worked perfectly even with the rimless shells."
I take that as meaning that the bolt face, extractor, slantbox mag would work with either chambering, however the 2 chanberings are quite different, Head dia. .400/.350= .465..... .350 magnum .515
So as you can see the 350 magnum case differs quite a bit with having much more taper in the case body on the Rimless case. Which case were you using when the extractor broke? Appears you could chamber the rimmed case in a rimless chamber, however the chamber would be approx .045 dia. larger at the case head & that would cause quite a change in case dimensions upon firing & possibly sticky case upon extraction, hence broken extractor?
Just trying to help, working with a lot of unknowns here. I would certainly cast the chamber so I was sure which case the rifle was chambered for.

m4220

Edited by m4220 (06/12/15 05:00 AM)

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