Siamese Mauser in .405 Win or .303 British?

jbmauser

jbmauser

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I have a decent condition Siamese Mauser action that I'm trying to decide what to do with. I already have one in .45-70 so that's not an option and I would like something a little different. From what I can see the .405's rim should fit the bolt face with no modifications but the COL is a little long for the factory mag well. I'm sure I could easily extend the front of the mag well and no modifications to the lower receiver locking lug, other than some shaping, should be needed since the factory mag well sits in front of it and acts as part of the ramp. This could be done away with and just extend the front of mag well to be flush with the locking lug, then contour the lug edge for proper feeding just like any normal 98 action. Maybe some receiver rail modifications for feeding as well? I'll have to get a dummy round made up and see how it will work.

Anyone do this before? Any thoughts?

I have a gunsmith friend that has built 405's on P14 actions so he has the reamer and know how on those actions. It shouldn't be too hard for him to do it to the Siamese.

Another option I am considering is .303 British. I have a ton of brass, loaded ammo, Barnes TSX, etc for the .303 but no rifle. The only thing I'm worried about is the .303 rim diameter is a fair bit smaller than the Siamese bolt face. It still engages the extractor with good spring tension. Any thoughts on this conversion?
 
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I just did a little testing with .303. It definitely has the potential to feed through the action. I'm going to have to fool around with followers to see if I can get it to feed better. Right now the dummy rounds sit too high up in the receiver and there isn't much holding them against the feed rails.
 
7.62x54 eh? I like that idea. Just checked and the rim diameter fits the bolt face perfectly! Unfortunately I don't have any dummy rounds and only one brass I set up as a trim gauge for my Forster trimmer so I can't test feeding but I bet it works better than .303.

I have a ton of .311 projectiles so I don't really need a .308 barrel.

Why did I sell all my 7.62x54 brass and dies a couple years ago?
 
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jbmauser said:
7.62x54 eh? I like that idea. Just checked and the rim diameter fits the bolt face perfectly! Unfortunately I don't have any dummy rounds and only one brass I set up as a trim gauge for my Forster trimmer so I can't test feeding but I bet it works better than .303.

I have a ton of .311 projectiles so I don't really need a .308 barrel.

Why did I sell all my 7.62x54 brass and dies a couple years ago?
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My Lapua brass sure works well for me.
 
There really is a large selection of rimmed cartridges that will work through the Siamese action with minor modifications. 30-40 Krag is another interesting option.

I'm liking 7.62x54 more and more tho. It would allow me to use up all the .311 bullets I have stored away. .303 would be better except for how it fits the bolt face. It seems it's been done lots as well but I'm not sure I like the idea of the smaller rim.

How does bolt face diameter vs cartridge head diameter affect function? Will I be ok as long as the extractor has sufficient spring tension against the case? Will it cause feeding issues?
 
Makes sense that 7.62x54r would fit well considering the Siamese 8x50r was designed to be able to chamber in a Austrian 8x50r rifle (the M88/90), and the Austrian 8x50r and 7.62x54r are very close in brass dimensions (so close that in WWI when Austrian troops ran out of 8x50r they would load 7.62x54r in there rifles).
 
7.62x54 would be cool. 7.7x56r would be cool too. The .003 difference in diameter re .308 is largely academic (ballistically academic too) unless you're wanting to shoot a lot of rounds and need the diversity. Plus I imagine you could load the rifle pretty hot.
 
brybenn said:
410 and use brass hulls. Be different. A small game getter to match your 45/70
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I actually tried this (well, fitting .410 shells in the action, not barreling it to this) and it would work well I think. I'm not sure it would have much practical use though. It would end up a heavy, weak shotgun. I agree it would be something different though.
 
Well, if you are looking for thoughts and opinions why not go back to the original chambering? That would be interesting and for sure pretty uncommon on the firing line, unlike a rifle chambered in 303BR.
 
bjmurata said:
Well, if you are looking for thoughts and opinions why not go back to the original chambering? That would be interesting and for sure pretty uncommon on the firing line, unlike a rifle chambered in 303BR.
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I thought about that as well but I have several 8mm hunting rifles already. It just doesn't appeal to me for some reason.
 
I have two SMLE's in .410, one original 2 1/2", one 3". We fire lead balls out of both. Is the barrel in your Siamese toast? I know the term "8mm" is rather a loose one. What is a Siamese bore? If a 7.62x54R works as far as brass goes, would it be feasible to blow out the brass to the bore size and fire custom lead bullets or balls out of it. Maybe I should quit while I'm ahead! :p
 
I would go for the 7.62x54 myself as it would be fun to have a Mauser to go along with my Mosin Nagant 91/30.
On the subject, a 20" barreled carbine in .33 Winchester would be the cat's ass on the fat bastards in the bush.
:)
 
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