Help with a 1908 Brazilian Mauser

[thoma018]

I've come across a rather plain but beautifully stocked 1908 Brazilian Mauser. Problem is we do not know what cartridge it is for; no caliber designation on the barrel. The barrel at the muzzle gauges out at .284 so that's good and leads one to think that it may be a 7x57 based on the history of the Brazilian Mauser. The seller thinks its a 7x57 BUT no way as the bolt face is very large, much larger than a case head for a x57. I tried my 7x57 go/no go gauges and of course the extractor will not even hold them as its to large; same with a 7x57 dummy round. So I'm thinking this could be as simple a a 7mag or as esoteric as a 7x66 Von Hoffe or 280 Halger; (there are other possibilities also: 7x73 Von Hoffe, 275 H&H, 276 Hoffman, 280 Remington, 280 ross and perhaps others. My dilemma is whether to purchase and and cast the chamber with Cerro safe to determine the cartridge---problem is I do not want a barrel burning, over bore rifle that I may or may not be able to find/purchase brass for &/or good current reloading data. It could be a 7 STW which could be quite simple to load for but again a barrel burner. My next step is to try a 7mm Rem mag int he chamber and see how it fits or what indication it may provide. I could live with another 7 Rem mag but I'm in a quandary. Even if the bolt face will accept/hold a 7mm case this still does not prove it isn't a larger case. I'm a hobbyist that enjoys chasing down these things but need some help on this. this rifle is a at a retailer so I am limited on what I can do/how I can evaluate this chamber. Please comment and prod me to think a bit deeper on laying out cash on such an unknown and offer your suggestions.

 

[bluefish]

Perhaps cast the chamber?

 

[thoma018]

of course but its at a retailer and they will not allow that; that is why I'm asking everyone to think outside the box....

 

[Ontario Hunter]

Start by looking at the box. Has the bottom metal been modified/changed? 7mm magnum is 0.22" longer than 7x57. Is it possible someone has swapped bolts just to put the gun together from odds and ends? Seems unlikely to me that a wildcat cartridge barrel would be made for a Mauser without the name of cartridge or maker on it. I suspect it's something more generic.

 

[thoma018]

Thanks, all provoking thoughts. The mag box looks unaltered but deserves a better look with measurements. I also thought it might be a "parts" gun but the wood/the lines of the stock and condition of the metal are all to nice to have just cobbled something together for a resale.
Being a 1908 Brazilian makes the action a "true standard large ring" although the bolt face is so wide it looks like it would easily take a large magnum case head.
We compared another 1908 Brazilian bolt, (from a 7x57 rifle), to the one in this rifle and the known 7x57 rifle had a bolt in it that was just very slightly longer than the "mystery caliber" gun. Didn't mic/measure that, just thought that was strange. I suspect its more generic also but its obviously still unknown at this time.
Without dropping some cerro safe in the chamber I guess there is no way to know and that is exactly why I'm tapping into the forum....lots of smart and knowledgeable folks on here and perhaps a "lightbulb moment" will occur for me.
As I said, my next move is to revisit the gun store with a 7mm Mag case and see if it will chamber.
Please continue to offer suggestions/ideas/thoughts. I'll post a couple photos I took of action/floorplate/bolt face.

 

[AZDAVE]

Chamber cast is the most accurate way to find out what you have.

If you have a set of calipers what is the measurements of the bolt face?

Measure the inside length of the mag box, and width at the rear middle and front of the box. This will determine if it has been modified to fit a mag style cartridge.

 

[Ontario Hunter]

Does not appear the locking ring was trimmed for a long magnum caliber (e.g. 300 H&H or something Weatherby). A look inside the open receiver should tell if the mag box and loading ramp have been altered. That is military bottom metal so I'm thinking the box wasn't majorly altered if at all. Again, all this is curious. Why would a smith put fine wood on a build project and not lable the caliber if he changed the caliber/barrel? Makes me think the bolt does not belong to this rifle. What other modifications? Does it still have the military safety? Has it been tapped for scope? If tapped + military flag safety = something amiss.