Does anyone have the water capacity and dimensions of the 3 cartridges I listed?

Ammoguide is a great resource, but it is way off the mark on case capacities.

For instance, it claims the 460 WBY has only 128.5 grains of gross water capacity. Baloney!
Those are numbers generated by the owner's pet software. No real measurements of case capacity there.

AccuLoad and QuickLOAD are better, but they vary just like different lots of brass vary.
At least the data there seems to be inputted from some actual measurements with water and brass in hand.

Use once-fired cases weighed on a digital scale, empty for the tare, then filled with water.
Fill to near top with a syringe, then finish off the fill to flat meniscus using microdrops from a syringe with needle.

Do five of the cases.
Get an average for the gross water capacity.

I did for the 450 Dakota and the 460 WBY.

"DAKOTA ARMS 450" headstamp (possibly made by Norma): 138.8 grains

"WEATHERBY 460 WBY MAG" headstamp (made by Norma): 142.4 grains

That batch of 460 WBY brass weighed 318.5 grains per case.
That batch of 450 Dakota weighed 324.5 grains per case.

My 450 Dakota brass is 6.0 grains heavier than one batch of my 460 WBY brass,
and has only 3.4 grains of water less capacity.

138.8/142.4 = 97.47 per cent,
The 450 Dakota is 2.5% smaller than the 460 WBY.

However, another batch of 460 Wby brass that I fireformed into .510/460WBY weighed 325.5 grains.
That 460 WBY batch #2 might have been closer to the capacity of the 450 Dakota than batch #1 was,
if the alloy of the case was the same composition.

I have no 450 Rigby brass. Maybe sumbuddy who know?
It appears (from reamer and chamber specs) that the 450 Dakota will chamber in a 450 Rigby, but not vice versa.

This ought to be pretty close to the nearest grain:

450 Dakota: 139 grains
450 Rigby: 140 grains
460 WBY: 142 grains

But, if the 450 Rigby brass is thinner (I doubt it) it might actually be bigger in capacity than the 460 WBY.
IIRC, Horneber and Jamison make the 450 Rigby brass, Norma PH too.
None of them make puny brass.

The .510/460Wby cases from the heavier #2 batch of 460 WBY brass ended up with 147.5 grains of gross water.

My 500 Mbogo has 155.8 grains of gross water capacity at max length of 3.000".
I'm just sayin' ...

AHOY!

Pierre van der Walt has this in his International Big Bore cartridge Load Data Collection:

Relative Case Capacities:

450 Rigby: 137.3 gr water
460 Weatherby Magnum: 137.7 gr water

Max Average Pressure:

450 Rigby: 58,016 psi piezo CIP
460 Weatherby Magnum: 63,816 psi piezo CIP

No listing for the 450 Dakota in van der Walt's book.

So it seems they are all within 2.5% volume of each other
So it seems they are all within about 0.625 per cent of same velocity, if loaded to the same pressure, which they are not.

If all were loaded to 460 WBY pressure, and the 460 WBY could do 2700 fps with a 500-grainer,
then the other two could do over 2680 fps.

Add 2 inches of barrel, the right bullet, load correctly, and the Weatherby will see 2700 all day long (and be safe) ...

OK,
So all three with 24" to 26" barrels could be loaded to +2600 fps with 500-grainers if you want to get pressures over 60K psi.

The Dakota and Rigby work with 500-grainers in the range of +2400 fps and +50K psi.

To finish picking the fly poop out of the pepper:

smallfry,
The case dimensions are obtainable with search function use on this forum.
Ammoguide is good at case linear dimensions, but not gross case capacities.

Factory barrel on a .460 is 26". What does quackload say about 115+ grains of RL19 - RL22, Fed 215, and a 28" barrel with some sort of real bullet ...?? Maybe VV160 & 165 are worth a look too.

Jay,
Everybody knows the factory 460 Wby Mark V has a 26" barrel.
Of course some of that barrel on my old "Deluxe" was eaten up by the Pilkington muzzle porting/brake.
I was shooting a 460 Wby about the time I got out of diapers, over 25 years ago.

"quackload?":
Too much fly poop!
The 460 Wby has about a 15 fps advantage over the other two, in same barrel length and pressure.

quote:

Originally posted by RIP:
Jay,
Too much fly poop!
The 460 Wby has about a 15 fps advantage over the other two, in same barrel length and pressure.

The caffiene's got me again ...

Thank you much RIP and Macifej. I was asking because I own a 22" 460wby on a 550. and had always wondered about the 450Rigby and Dakota. Mine has the Weatherby freebore and I can reach 2500 with some 500gr loads(is this a sane load?). I wonder if the freebore helps? Another interesting aside is that if you run hi-velo 450grainers that have high BCs it seems to me you come out ahead of high velo 416 Rigby/Weatherby loads... do you find this to be true?

AHOY!

Pierre van der Walt says the "relative case capacity" of the 500 Jeffery is: 154.2 gr water

500 Jeffery "Max Average Pressure": 46,412 psi piezo CIP

AHOY!

2500 fps in a 22" 460Wby with 500-grainers sounds good.
You are only losing about 100 fps by chopping off the barrel from 26".

No flies on the 460 Wby throat, of late.
And, say ... that is the only real trick the 460 WBY has up its sleeve over the other two.

Too close to call for me on the 460Wby-450-grainer versus the 416Wby-400-grainer.
Both at 2700 fps?
Maybe the 460Wby-450-grainer could go faster than that, 2700 fps in a 22" barrel or 2800 fps in a 26" barrel, but
both may be too much of a good thing.

Smallfry , That is what I should have done with my CZ Lott ......... ..
.
. RIP and Mac . Thanks for the entertaining education .... What is that you say . doin good has it's own reward ....

gumboot458,
Welcome.
Just endeavoring to persevere here.
smallfry did bring up the Weatherby throat, neglected by us until he did so.
That seems to be the only real difference between the three, the throating.
Not really significant either,
just a little pressure let-off valve for the WBY, so you gotta add more powder to get pressure back up to 63K psi,
and maybe add a few extra fps.

So let me rephrase/qualify something, please:

Were it not for the extra freebore, the 460 Wby has only about a 15 fps advantage over the other two, in same barrel length and pressure.

For what its worth, the 400 grain North Fork at 2750 fps stood up to point blank buffalo, so a 450 grain at 2,700 fps should be fine.

Not too much of a good thing for the bullet, but maybe too much of a good thing for my shoulder, vertebrae and retinas!

Andy

quote:

Originally posted by smallfry:
I can reach 2500 with some 500gr loads(is this a sane load?).

weatherby quotes 500gr at 2600 as factory .. www.weatherby.com

gumboot458 I guess you could do another CZ project!

Andy... what was your barrel length on your 450 Dakota?

Jeffeosso I have not tried Wby factory ammo in my rifle yet I will have to see what velo I get considering I have a 22' with a faster twist.