I have finally decided what calibre I'm going to barrel a Siamese mauser action to. Because the magazine length limits COL to just under 3 inches I wasn't sure what calibre to choose. I wanted something with more range than the 45-70 and more power than the 7.62x54 R on the other end. The 338 cal had possibilities but the long ogive on most 338 bullets meant the bullet would have to be seated very deep to fit in the magazine. The 35 calibre was better bullet wise but I don't really need another 35 cal. I have a 35 W imp ,a long throated 350 Rem and a 358 Norma. I suspected the 35-348 Imp would be about halfway between the 350 rem & the 358 Norma. Not a lot of room there. I was measuring up some possible COLs with some of the 375 cal bullets I had on hand and the 270 Hornadys and the 260 gr noslers both have a short ogive and should work great. The 348 Imp case will be very close to the same capacity as the WSM family of cases with a little longer neck. I suspect velocities will not be far behind the 375 H&H. I think this should make quite an effective "thumper" for elk ,moose and black bears. Most rifles chambered for some 348 wildcat will be built on lever actions. Anyone out there have any experience with the 375-348 Imp? Would appreciate any comments.

The 348 Improved case holds around 80gns H2O, the 375 Dakota is at 99gn H2O. Do you have to use a rimmed case in the Siamese Mauser? You could load the Dakota to much lower pressures and get the same performance. Or go with the 375 Ruger and have cheaper dies, brass...
I don't have a Siamese Mauser, so I might be missing something obvious.

Lar The Siamese mauser was designed to use a rimmed case. They were originally chambered in the 8x50 Rimmed Siamese and then most were converted to the 8x52 Rimmed. The rim diam was approx .560" and the magazine is slanted rearward so the rim of the top cartridge in the magazine is slightly ahead of the one below it. Most can be made work with rimmed cartridges such as 30-40 Krag ,7x62x54 rimmed,45-70 or the 348. The bolt face has to be opened up to use the 45-70 or 348 cases. The magazine will not accept the longer cartridges you have mentioned.

What about the .450 Alaskan?
Tom

I just started using a .375/348 Improved this last summer. Mine is an M71 Winchester(Browning) It has a 20" barrel and Williams peep and a large bead front sight. It is my idea of a walking about rifle for when I return to Alaska, where I bought it. I was living in Juneau, at the time.
I use 300gr Hornady round-nose for my bear-bullet, and that's what's in the tube most of the time. The oal is kept at 2.79" to feed thru the action, tho' bullets out to 2.81" will work, most of the time. The Hornady cannalure is below the case mouth, and the ogive has started by that point,too.
My starting loads with IMR 4320, H380,Ramshot Big Game and Hunter have been at 2200fps and "QuickLoad" predicts slightly over 2300fps for maximum charges or lots moe powders. Remember that I have a 20" barrel, and I also used 45000psi as a max because of the lever-gun.
I also use a 300gr lead bullet with a large meplat at 1300-1750fps for practice and smaller game. Black bear, elk, moose and deer shouldn't be any problem. You, of course, would be able to improve on these ballistics, quite a bit with a longer barrel, and higher pressures.
FWIW The .450 Alaskan has a lot of taper for feeding in lever actions, and moves a 500gr bullet, which causes it to move on both ends. If I were going that big, I'd look into the .45/348 Ackley, which easily rivals the .458 WinMag, at least with factory ammo. My 1 1/2 cents would use the 348-case in the Mauser.
Above all...have fun.

Have you read "Big Bores" by Wolfe Publishing?

They tried a Mdl. 71 in .348, .450 Alaskan, .416 Alaskan, and settled on the .416/.348 Improved.

I have that rifle and have used it on lots of bears, both black and grizzly, and believe it to be the cat's meow, ......lots of punch and recoverable for a second shot at close range, and a great brush gun also. Would most likely work out fine for the Siamese, I have one of thoose in 30-40.

Take a good look at the articles.

~Arctic~

Nevmaverik Thanks for your reply . That is exactly what I was looking for. I suspect you are right that I will be able to increase pressures a little with the mauser action. To the others ,Thanks for your input as well. No I'm not interested in a 416 Alaskan or a 450. I HAVE decided on the 375 calibre. I have 416 Rem and a 458. I really don't think I need another rifle in either calibre. In making my decision I referenced a number of books including " Big Bores and PO Ackley's handbooks It would seem the idea of short fat cases are not new at all .The Payne line of cartridges 348 cases with the rims turned off to make a rimmless cartridge were tested over 50 years ago. No doubt the 416/348 would make a great close range stopper. I was sort of thinking on a handi bolt action stopper that could reach out to 300 yds or so in a pinch. I think the 375/348 imp will do that. I have the action and dies. The stock is on order and the new barrel will be ordered soon.

eeeww, eeew. I need more details. Tell me what the ballistics on the 416/348 and the 375/348 AI. The 416 version might be a sane big bore to start with. How does it compare with the Taylor?

Per my source (Rifle Magazine's - "The Legacay of Lever Guns" - Jan 2000)

The .416-348 AI will do:

2,240 fps with a 360 gr LBT
2,030 fps with a 410 Hoch
2,015 fps with a 400 gr Barnes Custom

The .375 Alaska will do:

2,300 fps with a 220 gr Barnes
2,650 fps with 250 gr Hawk
2,500 + fps with a 270 gr Hawk

Barrel lengths were not specified.
Loads upon request.

MM

The ballistics quoted by Muskegman are for a model 71 lever action. Pressures have to be kept quite modest as there is not a lot of material in the chamber area. This is not a concern with the barrel on a Siamese Mauser. Perhaps it would be more useful to measure the velocity and energy of the flat nosed 416 bulets and the 375 spitzers at appox 100 yds. While the Siamese action will handle more pressure than the lever don't run away with the idea you can load it quite as hot as you can on an action that would be chambered to 416 Taylor.

Hi: I'm the fellow who corresponded with you on the Siamese Mauser...
I think a .348 based parent case would be the best in the Siamese Mauser...I agree with Arctic...would choose one of his suggestions...but if you are set on a .375, then a .375 based on the .348 case would be fine.
Best Regards,
Tom

Hello Tom Yes I remember you and thanks for the reply.I have a question for you. With the ballistics quoted by Muskegman the 416/348 Imp will be approx:
400gr@ 2015 fps approx 3608 ft/lbs
360gr @2240 fps approx 4014 ft/lbs
The 375/348 Imp will be approx:
270 @ 2500fps approx 3750 ft/lbs
250 @ 2650 fps approx 3901 ft/lbs
The Siamese mauser action will handle a little more pressure so it will boost the velocity of both but the comparison won't change much.
There is not a lot of difference at the muzzle. Most of the 416 cal bullets that are readily availible are round nose except for the 350 gr Speer. They will shed velocity rapidly and the trajectory will get a little steep. I agree the 416 will deliver a heavier bullet to a close range target with ample stopping power. But thats not what I'm looking for. If I want stopping power I'll just carry my 458. I was looking for a rifle that would be handy to carry yet reach out 250 yds (or maybe a little further in a pinch). I think the 375/348 with the 260 gr Noslers would be a pretty effective combination giving up very little to the 375 H&H in power or trajectory. Those spitzer bullets will carry that stopping power well past the range of the round nose 416 cal bullets. So why do you think I would be better off with a 416?

I have no less than 3 of the Siamese actions. Also a reamer that makes a 45/70 necked to 375. Nice shoulder angle too. Should feed good and have a lot of punch. Bet Ol` Dave at CH4D could make a set of dies cheap enough. I know Jerry at Royal Arms Gunstocks has a nice pattern. Might make a nice project for the winter [if I live that long!]LOL

Aloha, Mark

bohica I had considered using the 45-70 case but ended up going with the 348case for max capacity. I have to open up the boltface for the 45-70 so a few thou more for the 348 case is no big deal. You are right about Dave turning out a set of dies at a reasonable price.He made my 375/348 Imp. What other projects are you considering with your actions?

Gentlemen I have my 375-348 Improved all together and it is shooting just fine. 270 gr Hornady spire pts are giving me 3 shot groups of 2 in @ 200yds . Cases fireform with zero problems. Trying to get close to a moose with it but the weather has not been co-operating. Dam wind.

What! no photos?

Built 2, 45-70's , 1, 450 and 1, 50 Alaskan on the Siamese.

Worked well in all instances.

The 375/348 or 416/348 versions should work equally well.

Doug I will try and get some pictures. Might have to send to you to get them posted.
Dugga You may be correct. I chose the 375 because there is a wide variety of bullets of which many have a short ogive. they suit the Siamese magazine nicely.I just didn't see the need for another 416 as I already have a 416 Rem. The imp 348 case is almost bang on the same dimensions as the 300WSM necked up only the 348 case has a longer neck and is rimmed of course.I have more load developement and chronographing to due but that will be next summer. As is this thing is less than 100 fps slower than my 375 H&H . Out to 250 yds or so this thing will be quite a little "Thumper".

What a neat project. What barrel length will you be using? Would it be possible to build this into a mannlicher full stock with say a 18.5 to 20 inch barrel? How about pictures of the project as it moves along? Thanks DW

Send the photos. I will be glade to post them.

blkdouglas@charter.net

Gentlemen I finally have some pictures and I have attempted to send them to Doug to post. However I keep getting a message back telling me I'm sending to an invalid address. Can anyone else help me here?

Posting photos for Snowman.




Picture # 1 is one side of the rifle. It is a Siamese mauser with a 24 in McGowen barrel chambered in 375/348 Ackley Imp. The Richards stock still needs some more oil and polishing but it is usable as is. It has a 4x Refield with the heavy duplex. The rifle also has a model 70 type safety .So far all I'm shooting is 270 gr Hornady bullets and it groups 3 shots in approx 1 1/2 inches at 200 yds. Plenty good enough for what this was intended to be used on.

Pic # 2 empty brass left std 348 case, second from left 348 case sized to 375, middle fireformed 348 Imp case,second from right is a loaded 300WSM and right is a 350 rem mag case. Pic # 3 is tha same as # 2 with a different background.

Pic # 4 loaded rounds. Left is a long throated 350 Rem, second from left 375/348 prior to fireforming, second from right 338 win and right is the 375H&H

Just curious if anyone out there has some experience with the 225 gr Hornady .375 cal bullets in the 375 Steyr cartridge. Considering trying some lighter bullets on deer in my 375/348 Imp. I might be better off trying the 235 Speers. Would appreciate hearing about any experience that may be out there.
Merry Christmas to Everyone.

Picked up a box of .375 cal 225 gr Hornady bullets. Preliminry results show they do not as well as the 270 gr Hornady spire pts do. Has anyone out there tried the 225 gr bullets in the 376 Steyr or any other wildcats?? If so what powders have been working for you??

I've used 220 gr Hornady flat points as a deer/hog bullet, basically replicating a 375 Win. Great short range thumper at about 2200 fps. Bob