Standard Length Large Bores

[Jimbob]

30-06 length Mauser actions seem a great choice for people who can't afford a magnum Mauser action. You can get a Parker-Hale Mauser or BSA CF2 here for less than £200 (approx $315).
Not as nice an action as an FN but at the price a very affordable starting point.

Now my question is this; do standard length large ring Mausers have the same ability of taking the wide cartridges like the magnum actions can regards rim diameter?

I.e. Could you take a 30-06 length cartridge based around a 460 Wby/416 Rigby/505 Gibbs (I know the first two already exist in several forms) and, feeding issues aside, have a relatively affordable dangerous game gun?

Thanks in advance.

 

[stug]

10.75x68 was designed to fit a standard mauser action.

 

[Jimbob]

Yeah that's the kind of thing....except bigger!
I'm wondering what the limit is in width for a standard Mauser.

 

[IronCowboy]

How big are you thinking? There are plenty of "standard length" cartridges (3.340" or less) in larger bores, but there's a reality of how much powder you can pack into a case of a given length: Ruger magnums in 375 and 416, the 458win mag, the B&M WSM types, 9.3x62mm, etc etc. The Ruger 375 and 416 were designed specifically to that end - lots of power in a lighter, shorter, standard length action.

A guy might be able to trim and fireform a 416 ruger case into a tapered shoulderless 45 cal - then you'd have larger capacity than a 458win mag. Or something similar on a shortened and blown out Remington Ultra Mag case, or even on a WSM case (the B&M types).

I'm working on two rifles right now that are Ruger M77 Hawkeye standard length actions with magnum bolt faces, converting one of them to 458win mag.

 

[Jimbob]

Well it's more a 'what if' kind of deal.
For example, i know you can get a 460 short a-square so the next step in base diameter is the 450 Majoor which is based on the 416 Rigby. However, could we go bigger with a 505 Gibbs based wildcat.

Unfortunately a tapered, shoulderless 416 ruger wouldn't work as it would have nowhere to headspace. Same with RUM and WSM. All need a shoulder, like the B&M's, even if just a ghost one.

Also, the 450 Majoor has a larger base diameter than the RUM or WSM so if they shared all other geometry (length to shoulder, taper, shoulder angle and, of course, caliber etc) the 450 Majoor would have a greater case capacity.

I've just been messing around on QuickDesign and wondered if I actually have a home for one of my wildcats

 

[IronCowboy]

Right - for the RUM/WSM/Ruger based 45cal's, you'd have to have a shoulder. Just thinking about that logically, the Ruger is the same max dia as the belt on the 375H&H case, so you'd have to have a bit of a shoulder to get it down to 45cal. I'm thinking taper angle parallel to the 458, so instead of headspacing on the belt at the back, you'd have the same amount of stepdown at the shoulder instead. Without getting out a pen and paper, I'd assume going up to a 500 wouldn't leave you enough shoulder left to headspace.

 

[Jimbob]

Right I see what you mean now. I think it'd be a great little cartridge, I imagine it's probably out there. I'll google it tomorrow.
I agree that .50 or .51 would be too far.

The cartridge I have worked up is basically what you describe but a 505 Gibbs shortened and given a .510 bullet (easier to get hold of than .505). I'll post the case capacity when I finish work tomorrow but if I recall correctly it's a little under 150gr water (although I also have 135 in my head for some reason!)

 

[IronCowboy]

Yeah, sorry, I said shoulderless in my first response, been missing sleep lately and my mind wandered - a gentle taper and a nice and tight shoulder to allow headspace, I think you could pack a lot of fun into a standard action.

 

[Jimbob]

Right so the cartridge I've drawn up is 3.186" long overall which is designed around the 570gr .510 bullet. It holds 152.1 grains of water. That's 14.1 grains more than a 500 Nitro so probably going to clout a little at both ends.

But the question remains, can a standard Mauser take this girthy number?

 

[IronCowboy]

I suppose I'd take a quick review of it to look at your overall diameter against your projected chamber pressure. Are there other cartridges that are THAT FAT with the same type of operating pressure?

I have heard of guys doing WSM conversions on Mauser actions, that'd give you a max base dia of 0.555" on a magnum bolt face, with an operating pressure of 65kpsi. The Rem Ultra Mag's are at the same 65kpsi limit, with a case dia of 0.550" too. That Gibbs case will be a bit fatter still, at 0.640". A guy should be able to punch out the numbers on the relative strength reduction in robbing ~50thou of skin on the inside of the chamber.

Are the magnum mausers larger diameter than standards, or just longer? I've heard of 505 Gibb's Mausers before, although they're only running ~39kpsi. Your estimation for thrust should be pretty straight forward, but I suppose I'd take comfort in the fact that the lock up can handle the 505 Gibbs itself, surely it can sustain about the same power out of a shortened high pressure version.

So, I might be over-simplifying here:

1) I'd be confident to check the box that the lock-up can sustain the thrust IF the long mausers are the same diameter of the standards, based on the fact that that 505 Mausers exist.

2) I'd run the calc's on the proportionate strength loss going from a known sustainable 0.555" at 65kpsi cartridge down to your thinner wall with a 0.640" case. That'd give you your maximum pressure sustainable in the Gibbs case - assuming that the brass itself could be ramped up to that pressure as well (I have no experience with the Gibbs case, so I don't have a reference for its construction).

As long as your pressure calc's line up with that proportionate strength ratio, then I'd take a shot at building it. I might shoot several over pressure proofing loads out of a "research action" (aka sacrificial action that got melted down afterwards) from a fixture first, but if the numbers look reasonable, it sounds like a really fun project.

If I recall correctly, the B&M rifles MDM and B&M Mag's use RUM cases, but in Ruger and Win 70 actions. There may be a reason they're using the "thinner" RUM case, other than brass and rifle/action availability.

You're spot on though - high pressure, big bullets, short impulse, she's going to bang your teeth loose!

 

[Velo Dog]

Hi Jimbob,

Evidently the .500 Jeffery was designed (probably by August Schuler) to be more or less the largest and most powerful cartridge (primarily for commercial ivory hunting but it came along too late in that arena as most countries were banning such activity about then), that would still work in a military surplus Model 98 Mauser action, without having to remove so much metal as to be unsafe.
This seems to be the only reason for the rebated rim (just barely fits onto the bolt face with not much if any room left).
However, the cartridge body itself was fat enough that Agust Schuler, (possibly W.J. Jeffery did so as well? - not sure about that one) did not try to make many if any rifles for it with staggered box magazines, (at least pertaining to the comparatively "small" size surplus military actions anyway).

Instead, they used a straight feed magazine, in other words each cartridge rests directly on top of the next one down, like logs in a typical log cabin wall.
This required a deeper magazine so, Schuler (and Jeffery?) fashioned what look somewhat like a removable steel magazine box, protruding below the bottom of the repeaters in .500 caliber.
Westley Richards also used this design magazine on their .425 caliber Mausers (another rebated rim cartridge, primarily for dangerous game bolt action repeaters, this one approximately the same power range as the .416 Rigby).
However these somewhat odd looking magazines were not removable, only hinged at the front, similar in function (not similar in looks) to the floor plates on many of today's bolt action rifles.

This "straight-up cartridge stack" design seems to have eliminated potential feeding problems inherent with staggered box magazines when combined with rebated rim cartridges.

Cheers,
Velo Dog.

 

[Jimbob]

Thanks for the reply IronCowboy.

I'll finish of the calculations when I have a little more time (isn't it always the way).

However, QuickDesign works out bolt thrust for you. Running my wildcat at 505 Gibbs pressure it provides approx 1300kg more thrust than 30-06 but 1000kg LESS than 300 WSM.
At the low pressure of the 505 Gibbs it will comfortably exceed 500 nitro all day.
I am tempted to redesign it to a .458 for bullet availability....however I already have a .458!

Cheers Velo. You know what, I knew that but never once thought "the Jeffery uses a rebated rim for a reason". This my friend is why forums can be so God damn helpful!

The Gibbs is .015 wider at the base than the Jeffery and the rim is .06" wider with it not being rebated. That's a fair difference and may be a step too far.

Thanks for the fresh set of eyes lads