416WSM on Siamese Mauser & 416/348Ackley Improved on Martini

[Ontario Hunter]

Well, if it feeds and extracts and ejects cartridges that are spec overall length, then no need to change the rails. Is it cycling smoothly? The 416 Rem Mag bottom metal I bought for my 404J build was also narrower in the shoulder than Paul Mauser's cosine 30 degree formula. Figured I could widen it enough but didn't need to. It works fine. In fact, it probably works better. With the shoulders squeezed a bit, the bullets are pointed more towards center of loading ramp. Your cartridge rim should be up and into the claw well before it is to shoulder area of rails.

Good work. I am surprised you are cycling rebated rim WSM this easily.
Bolt was not overheated or you would not be able to reassemble the shroud. Whoever put the bolt handle on mine was not so careful. I had to true up things when changing to new safety.

 

[Spearhead]

Nice lathe work.

 

[BlueFlyer]

The Siamese Mauser magazine spring is anaemic. The P14 & M17 have much more force and I will try to swap one into the Siamese Mauser.

 

[Ontario Hunter]

Okay, looking at your photos the mag box is single stack that transitions to staggered at the receiver. I agree you may need to modify the rails at shoulder otherwise it looks like bullet tip will be hitting chamber on opposite side as bolt closes. So tuning the rails, follow my instructions earlier. Put three dummy cartridges in the box and tune the contact rail. Then two in the box and tune the other rail, then with just one in magazine tune the follower only, reshaping it as needed. I used grinding wheel on Dremel tool. A little bit taken off then reassemble and check. It took me almost two days to tune the rails and ramp but I had a lot more metal to remove. Be patient.

Sorry but the site is giving me fits today. Stop and start. Getting hung up all the time.

 

[mauserhunter]

Looking good, mag fit is pretty close. Now I'm thinking a 375wsm would be cool or even use the ruger case.

 

[Ontario Hunter]

Okay, looking at your photos the mag box is single stack that transitions to staggered at the receiver. I agree you may need to modify the rails and receiver at shoulder area otherwise it looks like bullet tip will be hitting chamber on opposite side as bolt closes. So tuning the rails, follow my instructions earlier. Put three dummy cartridges in the box and tune the contact rail. Then two in the box and tune the other rail, then with just one in magazine tune the follower only, reshaping it as needed. I used Dremel tool with grinding wheel. Took me two days to modify rails and ramp but I had a lot more metal to remove. Be patient. Remove a bit, reassemble, try cycling, start over, etc. Very slow work. Do NOT want to remove too much from rails.

Sorry but the site is giving me fits today. Stop and start. Getting hung up all the time.

Is the box stamped metal?

 

[Ontario Hunter]

Sorry for double post. Site is all over the place trying to post. Something is going on.

 

[BlueFlyer]

I missed posting the photo of the tool & cutter grinder setup.

 

[mauserhunter]

I really need to buy a tig welder I've got a few bolts that need welding, one day I'll see if the old clapped out south bend can make some bolt stubs to.

 

[BlueFlyer]

Is the box stamped metal?

The box is milled, single piece.

 

[Ontario Hunter]

This has been an intriguing thread. I have a buddy who's got a couple of those Siamese actions for donors. He is convinced 45-70 is all he can build with them. I would not have thought the bolt face issue could be overcome.

 

[Rule 303]

If it's an 8mm rimmed version of the Siamese Mauser then it would require changing a 16mm bolt face and extractor into a 13.6mm WSM ... if that's even possible. But apparently some Siamese Mausers were made in 30-06 and even 30 carbine (ugh!). If one of those, then it would be a manageable build to open the bolt face and extractor. But can they be reduced in diameter? And you're probably correct about feed lips. The feeding rails for a fat rimmed single stack cartridge would have to be widened for a narrower cartridge = adding metal. Would seem to be a challenge.

Yes this can now be down with Laser Welding. Can add as little 1 thou I am told.

 

[Grumpy gumpy]

Re the bolt face, Laser welding or sleaving the recess will both work. Whoever does it will need to watch for heat transfer, but most competent welders could do it.
gumpy

 

[BlueFlyer]

Yes this can now be down with Laser Welding. Can add as little 1 thou I am told.

There has been a bit of discussion about the rebated rim on the WSM, but lets get a perspective. The cartridge base diameter is 0.555" the rim diameter is .535", that is only a 0.020" difference in diameter or a gap of 0.010" between the rim and rim recess on the bolt. 0.010" which is about 3 paper ticknesses.
In the Siamese Mauser if the WSM case moves against the bolt recess by 0.010" the extractor will still have 0.015" of engagement. At this stage I am just going to see how it functions. Laser welding does look like a good option.

The 425 Wesley Richards which started the whole rebated rim debate was an extreme. Due to contractural constraints WR had to try to get a 404J case into a standard K98 action and they chose to keep the standard bolt face for the 8X57. That is a step down of .545" to .470" or 0.075", almost 4 X the step down of the WSM.

Next step is to replace the SM magazine spring with a P14 spring.










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[Ontario Hunter]

Perspective is good. Thanks. Will you be working towards snap over or will there be enough room in the mag box to engage a fourth round under the claw and load it that way? I have both options on my 404J build. Pushing it under the claw is less strain on extractor but snap over is kinda handy for dangerous game when one might need to drop a shell in the chamber of an empty gun while dodging horns.

Can you add more tension to existing follower spring by physically pulling the leaf apart and reshaping it?

I ordered a new NECG magnum follower for my 404J build but it didn't match up to standard Mauser follower spring. The retaining slot in new follower was a bit too wide allowing the standard action spring to slip out. I fixed it by putting the follower in vice at the point where retaining slot was located and squeezing till the sides crimped in slightly, enough to hold the spring in alignment with follower. Something to keep in mind if you run into the same issue using an Enfield spring.

 

[BlueFlyer]

Will you be working towards snap over or will there be enough room in the mag box to engage a fourth round under the claw and load it that way?

When I hinge the floor plate I am contemplating machining up a whole new floor plate with a deeper belly per the Mauser design to ensure I can get 4 rounds in. Currently it is the large shoulder that is limiting the capacity to 3 rounds currently. The extractor can snap over the rim, but as you said, I don't like doing it, only in an emergency.

On top is the Siamese Mauser magazine spring - under it is the P14 spring. The SM spring uses 0.39mm material and the P14 is 0.5mm, plus the P14 is higher so will have more preload. The P14 almost assembles directly into the SM floor plate and follower. Where the leaf necks down to engage into the retention groves, I just meed to grind the shoulder back a few mms and it will be all good.
This little mod is for another day

 

[Ontario Hunter]

When I hinge the floor plate I am contemplating machining up a whole new floor plate with a deeper belly per the Mauser design to ensure I can get 4 rounds in. Currently it is the large shoulder that is limiting the capacity to 3 rounds currently. The extractor can snap over the rim, but as you said, I don't like doing it, only in an emergency.

View attachment 617396

On top is the Siamese Mauser magazine spring - under it is the P14 spring. The SM spring uses 0.39mm material and the P14 is 0.5mm, plus the P14 is higher so will have more preload. The P14 almost assembles directly into the SM floor plate and follower. Where the leaf necks down to engage into the retention groves, I just meed to grind the shoulder back a few mms and it will be all good.
This little mod is for another day

+1! Spring too wide is always better than too narrow. I see what you mean by "anemic". That SM spring is thin as paper.

So you will be machining your own floor plate? Wow. Should be quite the feat. Because the Siamese box is angled for rimmed cartridges, I suppose all you need to do is drop the front end of floor plate a bit to get the extra depth for fourth round capacity? Do you plan to widen the box at shoulder or just the receiver and feed rails?

Good work. Very interesting project.

 

[mauserhunter]

I just a few months back put a 98 mauser spring in my ruger ts 77 7x57, fit right in. Every once in a while they second round in the mag wouldn't pop up all the way and the bolt would miss it, only ever happened at the range not hunting think since I work the bolt slower at the range it would mess up. The old spring felt so weak even compared to a 100 year old 98 spring.