Why not a .590 Short Mag?

[TheDerkster]

Seems that short mags are coming back. Lot of people around here are picking them up and some going as far as to collect all the WSSMs and WSMs. Im personally going with a 7mm Sherman Short Mag when I get my krieger.

But all these mags are basically based off a .550 bolt face. There is a .590 bolt face ya know...

As far as I know, remington and savage both offer 338 lapua in their actions. People dont think the action is really stout enough either way, but my point is that the .590 bolt face does work. It doesn't leave much left though for enlarging the bolt head space. Savage would be easiest to convert with a simple bolt head change.

I just think it would be cool to have a short action magnum based on a .416 rigby case. Why not. We make all the other kinds of wildcats and a short action [super] ultra mag in 7mm and .30 would be just awesome. Long action magnum in a short action. I haven't run the numbers to see what kind of case capacity the extra .04 would add but I know its exponentially increasing due to the square nature of the equation for volume (r^2*pi*h).

I dont think one could quite reach a 300 win mag capacity without cheating a bit on length compared to a SAUM or WSM though, which defeats the purpose of having short action capability. Just thinking out loud here. I have 3 hours to drive everyday so I get to do that a lot

 

[J E Custom]

Seems that short mags are coming back. Lot of people around here are picking them up and some going as far as to collect all the WSSMs and WSMs. Im personally going with a 7mm Sherman Short Mag when I get my krieger.

But all these mags are basically based off a .550 bolt face. There is a .590 bolt face ya know...

As far as I know, remington and savage both offer 338 lapua in their actions. People dont think the action is really stout enough either way, but my point is that the .590 bolt face does work. It doesn't leave much left though for enlarging the bolt head space. Savage would be easiest to convert with a simple bolt head change.

I just think it would be cool to have a short action magnum based on a .416 rigby case. Why not. We make all the other kinds of wildcats and a short action [super] ultra mag in 7mm and .30 would be just awesome. Long action magnum in a short action. I haven't run the numbers to see what kind of case capacity the extra .04 would add but I know its exponentially increasing due to the square nature of the equation for volume (r^2*pi*h).

I dont think one could quite reach a 300 win mag capacity without cheating a bit on length compared to a SAUM or WSM though, which defeats the purpose of having short action capability. Just thinking out loud here. I have 3 hours to drive everyday so I get to do that a lot

It could certainly be done.

As to reaching the capacity of the 300 win mag, no problem.

The main reason for the short mag is to be able to use a short action and keep the overall length of the rifle to a minimum.

With big fat cases, feeding can be a problem unless you go with a center feed mag box, Then the only issue will be the mag capacity (2 or 3 normally).

There are many cases to choose from but I would go with the 416 Weatherby case because it has the same size case body as the Rigby (.581) and a smaller case head .579 as apposed to .590 for the Rigby. plus it is a much stronger case designed for more pressure.

With the 416 Case cut to the Cartridge length of the short mags, it should hold around 80 grains of powder.

I have built a 458 short mag by shortening the case .250 but that would still be a little long for a short action (About .140 long) but with the extra capacity of the 416 (378 Weatherby) It could be shortened enough to fit and still hold more powder.

Anyway, its fun to think about.

J E CUSTOM

 

[TheDerkster]

It could certainly be done.

As to reaching the capacity of the 300 win mag, no problem.

The main reason for the short mag is to be able to use a short action and keep the overall length of the rifle to a minimum.

With big fat cases, feeding can be a problem unless you go with a center feed mag box, Then the only issue will be the mag capacity (2 or 3 normally).

There are many cases to choose from but I would go with the 416 Weatherby case because it has the same size case body as the Rigby (.581) and a smaller case head .579 as apposed to .590 for the Rigby. plus it is a much stronger case designed for more pressure.

With the 416 Case cut to the Cartridge length of the short mags, it should hold around 80 grains of powder.

I have built a 458 short mag by shortening the case .250 but that would still be a little long for a short action (About .140 long) but with the extra capacity of the 416 (378 Weatherby) It could be shortened enough to fit and still hold more powder.

Anyway, its fun to think about.

J E CUSTOM

As you say, the 416 weatherby does have a smaller case head. The diameters at the shoulder and base area actually average out in favor of the weatherby The rigby has seemingly a lot more taper from the base to the shoulder based on SAAMI spec.

But is it possible to fireform those cases to less taper? Something more of a resemblance to the weatherby, which would give it noticeably larger capacity. Im not sure on the strength. Maybe you would have to go with 338 lapua brass? As far as I know, its based on the 416 rigby anyway and should be stronger compared to other brands from my experience with their other cases.

Reason definitely is short action. I feel like long actions have a lot more cycle time (even if only parts of a second) compared to short when Im hunting. I dont sit and shoot once. I walk and shoot multiple times at multiple deer. I hunt primarily for meat here in MO and whitetails can become a nuisance, so speed is key a good portion of the time. But I like to be able to reach out and touch them if need be so that is why I dont use an AR-10. My gun is centerfeed either way, but im sure the feed lips would need modified if not a custom mag made for a rigby or weatherby case.

Id more or less like to experiment more than anything. I have access to a lot of machining tools and probably tens if not hundreds of thousands of dollars of carbide tooling due to government surplus. Not that I can own it, but I can use it. Im just saying I might be able to learn how to make reamers and dies and just mess around with it within reasonable saftey limits.

 

[J E Custom]

It is also very common to reduce the taper on the case wall during fire forming.

PO Ackley recommends that body taper is not less than .007 thousandths per Inch of case body
(Any less can cause poor extraction in high pressure cases in actions with aggressive cam angles.

The problem I have with the Lapua is it's case head size. No question it is great brass and could be shortened and fire formed.

I would recommend having a reamer built by someone like Dave Manson and start with a great reamer and also a premium barrel.

Just my opinion

J E CUSTOM

 

[Deleted member 46119]

I played with a design based on a Lapua case.

I have more to do to compare it to WSM/SAUM and WM.

It fits a 230 Berger hybrid into a 2.8 COAL.

I will layout one on the 500 Jeffrey's and 378/416/460 Wby.

 

[TheDerkster]

It is also very common to reduce the taper on the case wall during fire forming.

PO Ackley recommends that body taper is not less than .007 thousandths per Inch of case body
(Any less can cause poor extraction in high pressure cases in actions with aggressive cam angles.

The problem I have with the Lapua is it's case head size. No question it is great brass and could be shortened and fire formed.

I would recommend having a reamer built by someone like Dave Manson and start with a great reamer and also a premium barrel.

Just my opinion

J E CUSTOM

Very good. Thank you. Now you have me actually wanting to build one like you did or of the .590 head. These forums get me in trouble.

 

[J E Custom]

Very good. Thank you. Now you have me actually wanting to build one like you did or of the .590 head. These forums get me in trouble.

I hear that !!!!!

J E CUSTOM

 

[sable tireur]

The Derkster,

There is an article right here on LRH:

The 7mm Fatso - The Ultimate Short Magnum!

Usually you can count on approaching too much of a good thing as in how big a cartridge can we shorten up to make a short mag? The same applied to how small can we neck a big cartridge down to set all sorts of record velocities?

Remember that it's the length of the barrels which will make a lot of difference.

I have done the 338 Lapua and the .460 Weatherby. The tooling costs were horrific for not nearly enough of an impressive gain. We are the slaves of physics after all.

Regards.

 

[TheDerkster]

The Derkster,

There is an article right here on LRH:

The 7mm Fatso - The Ultimate Short Magnum!

Usually you can count on approaching too much of a good thing as in how big a cartridge can we shorten up to make a short mag? The same applied to how small can we neck a big cartridge down to set all sorts of record velocities?

Remember that it's the length of the barrels which will make a lot of difference.

I have done the 338 Lapua and the .460 Weatherby. The tooling costs were horrific for not nearly enough of an impressive gain. We are the slaves of physics after all.

Regards.

Definitely. I guess for me, Im more in to the designing aspect. I dont worry so much about cost as I do just how much performance can you get out of a short action. Maximizing potential if you will for energy and velocity while maintaining accuracy. Ive seen the 7mm fatso, but didn't realize that is what it was. I actually considered building one just based on what I had seen but never really looked in to it heavily because I couldn't find much on it.

Thanks.