FN Mauser Conversion

[merbeau]

Over time I have acquired rifles in various calibers from 17 HMR all the way to 416 Ruger. At present I have a custom FN Mauser made in Belgium configured for the Rem 22-250 Ackley Improved that essentially is not used because I use either a Ruger 204 or Winchester 243 for varmints. I was doing some reading and found that the 500 Jeffrey was originally designed to fit in a standard Mauser action.

According CZ website they make a rifle in this caliber listing for nearly $3000 dollars. My question is can this FN action be rebarreled to a 500 Jeffrey (PAC Nor makes the barrel) without exceeding the $3,000 dollar CZ. I realize the bolt face would probably have to be opened up because of the larger case rim on the Jeffrey.

Also I would imagine that a stock might be the most difficult is not most expensive part and would that even be possible.

Thanks
Robert

 

[shortgrass]

Besides the bolt face needing to be opened the block would need to be removed from the magazine box and the feed rails and ramp would need to be 'opened' to allow the cartridge to feed. The extractor would need to be modified, also. For such an obscure cartridge you would need to provide the reamer and "GO" gage. The mag box with the block removed is or should be 3.340 long. Is that long enough for the .500 Jeff?

 

[merbeau]

Besides the bolt face needing to be opened the block would need to be removed from the magazine box and the feed rails and ramp would need to be 'opened' to allow the cartridge to feed. The extractor would need to be modified, also. For such an obscure cartridge you would need to provide the reamer and "GO" gage. The mag box with the block removed is or should be 3.340 long. Is that long enough for the .500 Jeff?

According the Barnes reloading manual (where I got the idea from) the case max length for the Jeff is 2.75 inches and the max overall length is 3.468 inches. Another one that may work is the 458 Lott.

 

[sable tireur]

The cartridge OAL is listed as being 3.468" so the shorter box won't cut it.

We always made our own bottom metal and boxes when it came to these cartridges with larger cases. And yes, hand made is more expensive.

Here's a reality check just to see how committed you are to this project.

You can try to scrimp by with modifications made to what your rifle came with. It will never be as good as what you want it to be because you are trying to shoe horn a long, fat cartridge into a system made for standard long action cartridge. Yes, it will work because we've done it before. But when we did it, we put our best foot forward making custom parts for the rifle. Measuring, making and fitting all the parts together from bottom metal to the box, the follower and spring is part science and part black magic. It takes knowledge, experience and time to get these fat cartridges to feed.

Scrimping, you might stay in the neighborhood of $3,000 but I'm not sure who you could interest in the project for that money. I'm sure some 'smith somewhere will assure that it can be done and that he's the one to do it. But check his work very carefully as you stand to lose a lot.

If you think I'm downplaying your idea, I'm not. But to get the kind of rifle you probably have in mind is not a project to scrimp on because you'll be disappointed.

Personally, I would pick a classic African Safari cartridge and enjoy the build. Trying to force a project together rarely satisfies the owner.

The .470 Capstick is guaranteed to rock your world.

The .458 Lott is a top cartridge for buffalo.

My favorite is the 9.5 x 66 SE vom Hofe.

Enjoy the process!

 

[shortgrass]

ST is absolutely correct. You have a 'classic' .30/06 length action. I'd stick with something like that. Lots of belted mags have been made on these. Sunny Hill Ent. makes several different bottom metals for '98s at an appropriate price, of course. Lots of hand work in going to a 'longer' cartridge into an action made for a shorter one. One of the newer mags that comes to mind that'd fit nicely is the .375 Ruger. But even that wouldn't be a "budget" project. Cartridge conversions rarely are (budget).

 

[merbeau]

The cartridge OAL is listed as being 3.468" so the shorter box won't cut it.

First of all, thank you to all that replied. I guess I should have mentioned that I currently own a 375 Ruger. And I appreciate all the comments and do not feel anyone is downplaying my idea. Conversely, at least you are saving me what appears to be a potentially expensive and perhaps disappointing project with all the gradations that will occur.

 

[375rifleman]

Hello, merbeau I have been looking at and wanting a Mauser (repeating rifle not a single shot/a more cost effective singleshot would be a tc Encore) chambered in 50 Alaskan with 750gr A-Max Bullets. How reasonable is this? I'm guessing that it would need to be a Siamese Mauser or Arisaka enable to deal with the big rim on this cartridge. What do you think?

Regards,
375rifleman

 

[.300 Dakota]

Howa Mountain Rifle 6.5 Creedmoor. 160 grain Woodleigh Weldcore seated into the lands...

 

[merbeau]

Hello, merbeau I have been looking at and wanting a Mauser (repeating rifle not a single shot/a more cost effective singleshot would be a tc Encore) chambered in 50 Alaskan with 750gr A-Max Bullets. How reasonable is this? I'm guessing that it would need to be a Siamese Mauser or Arisaka enable to deal with the big rim on this cartridge. What do you think?

Regards,
375rifleman

I would think the above comments apply in this case also. If I am correct the Alaskan is built of the 348 Winchester which has its own set of issues. Also are not these made for lever action rifles? The Alaskan is considered a wildcat cartridge.

 

[375rifleman]

You are correct metbeau, the 50 Alaskan is a wildcat it's basically a 348 Winchester necked up to .510 caliber. There have been leverguns on 50 Alaskan a lot of modified Winchester 71's, Brownings, or maybe Marlins. However what I'm trying to do prohits use in a lever gun except possibly one round chambered and one round in the tube. When a 50 Alaskan uses a 750gr A-Max bullet 1. It's a very 'pointy' round so not applicable for a lever gun 2. It's around 4" C.O.A.L. which limits most bolt actions 3. It has a very big rim .610 (I do believe) which further complicating things. The closest thing would be a 45-70 chambered Mauser or SMLE .608 rim (I think) except a 45-70 wouldn't commonly have a C.O.A.L. even close to 4".

 

[merbeau]

The rim on the Alaskan is 0.610 and the bolt face of my Mauser is 0.700 which would not leave much after machining. Brownells carries the CZ 550 Mauser actions and one for magnum action like 416 is ~$700. Most of what I have been reading suggest that for building a large bore dangerous game rifle a qualified big bore gun builder like Ryan Breeding do the work. Although looking at a site like Guns International some of those rifles go for $14,000 which is out of my league. And I looked at a box for the Mauser to handle the oversize cartridge and they are 600 to 1000 dollars. At this point I think probably best to save up to purchase a CZ rifle.

 

[.300 Dakota]

The CZ Safari Express 550 in .505 Gibbs rebarreled would do it. You MAY have a little too much bolt face at .635, though. The Gibbs loaded out would be about 4". Problem there is you've got $3000 into parts before you start the lathe. It would be much cheaper to buy a Stiller Tac 338 action and have .015" cut out of the bolt face, then barrel. You could have everything you needed for $2k. I would not fool with Rem or Sav 338 actions. Bolt isn't strong enough for that kind of thrust.

 

[J E Custom]

Shortgrass and Sable Tireur Gave you very good advice and all I can add is my own preference.

If i wanted to use the Mauser action, I would stay within its parameters, and build something that would not stress the action or modify it to much. Opening up the bolt face to more than a magnum bolt face in my opinion, over stresses these actions.

If you want to build a 500 Jeffery's, find a good donor like the Mark 5 Weatherby or some other large bolt action with a magazine length of 3.800 to 4.000 and you wont regret it. The advantage of the Mark 5 is everything is standard threads and there are plenty of stocks available for it. parts like custom triggers, 4.000 length center feed mag boxes,scope bases are common and they are 60o bolt lock up.

J E CUSTOM

 

[.300 Dakota]

Another possibility I forgot about is the Montana 1999 action in 338 Lapua, if you can find one.