Does this big bore cartridge exist?

[Northern Shooter]

458 Lott? easy to find bullets and brass. A real thumper, but not too crazy.

That’s probably the most logical choice but as an owner of a 458 WM we’re not allowed to like Lotts haha, I was hoping for something a bit more of a step up.

Now that I see 450 Rigby factory ammo can be had it’s becoming a serious consideration…

 

[CZDiesel]

470 Capstick, both Aria and Hendershot’s has ammo! You can load a 600gr round over 2200ftps!

 

[Wyatt Smith]

495 A square

 

[analog_peninsula]

Without the factory ammo requirement, I’d say the easiest path is the .500 A2.

 

[Northern Shooter]

The readily available factory ammo component is a big one for me. I don’t reload, like the convenience of buying it off the shelf.

 

[Certus]

470 Capstick, both Aria and Hendershot’s has ammo! You can load a 600gr round over 2200ftps!

.470 capstick - the cooler Lott.

 

[michael458]

@michael458

In 2009 I developed the 500 MDM, which is a 2.8 inch RUM case, uses a .500 caliber bullet. Not .510, but .500............

The rifles are Winchester M70 RUM actions with 20 inch barrels as standard. These rifles require a Accurate Innovations Stock with the full length aluminum chassis. Depending on the wood they come in at 8.25 to 8.75 lbs.

I have done extensive Pressure data, load data and bullet designs around all the .500s I developed.

In 2009 I had a really nice 550 gr Lehigh SSK designed solid. With several different powders I was able to easily hit 2175 to 2210 fps with it. However, I never used it in the field, there was an identical bullet 510 gr that I used on a couple of elephants and several buffalo getting over 8 ft of penetration in elephant, 550 was just not needed....... and this was very early on.

By 2011 we had developed the Cutting Edge #13 Solids for the .500s, and being a solid fan, I had .500 caliber solids coming out my ears..... 375 gr for 50 Super Short, 375 and 405 Lever Solids for my 50 B&M Alaskan guns, 450, 475, 500, 525, and 550 gr CEB #13 Solids for the larger bolt gun calibers 50 B&M, 500 B&M and 500 MDM........ I used mostly the 500 gr version on a lot of buffalo and a few elephants. The 500 MDM would run the 500 Solid to 2350-2400 fps and it would drive end to end on elephant and buffalo of course...... And knock the crap out of them as well.......

As for the 550 gr CEB #13 I had a load of 90/H-4895 that hit 2262 fps at 61800 PSI. And many other loads that would run 2137 fps 52000 PSI to 2216 fps at 58000 PSI......

But a 550 is just not needed or required for any reason...........

My personal favorite solid is the 525 gr CEB #13 in .500, but only if I was using it exclusively for elephant, 95/H-4895 runs the 525 gr #13 at 2361 fps at 63000 PSI, 94/H-4895 2338 fps at 61000 PSI, and a nice easy load 92/H-4895 at 2289 fps 57000 PSI....... this bullet drives extremely deep and hits hard as hell up front.......... End to end Elephant and bust bone in between.......

This is my English Stocked 500 MDM used in Africa many trips buffalo and elephant..........

This is my Myrtle Stocked 500 MDM with the barrel cut back to 19 inches. It was the first 500 MDM built in 2009 with a 20 inch barrel, used exclusively in Australia for 50+ buffalo............

My friend Sam has several 500 NE double guns, and we did a big study on 500 NE. Knowing what we knew about the CEB #13 Solids and heavy weights just not needed, he had Dan at CEB make a 510 gr .510 caliber #13 Solid, and matching 475 gr CEB Raptor for his 500 NE guns. We were able to run the 500 NE and 510 solid to 2306 fps at 43400 PSI and the 475 Raptor with the same load of RL 15 to 2312 fps at 39000 PSI...... This combination has been used in 500 NE since 2012 with incredible success on a lot of buffalo and a lot of elephant.

With todays bullet tech heavy weights are no longer required to accomplish the penetration needed.

I had another pet project a few years ago, 500 B&M. This is also a RUM case, but cut to 2.5 inches and uses the same Winchester M70 RUM action and 18 inch barrel. There were two of these built, I have both and never really turned them loose. These are extremely handy rifles at 18 inches.

This cartridge is quite capable as well, and it can run the CEB Raptors with Talon Tips added through the magazine, which was one of the reasons I designed it at 2.5 inches. You can see the Talon Tip load above in the cartridge photos.......

If you want heavy weight, the 500 B&M runs the 525 CEB Solid at 2185 fps with 84/IMR 8208 at 58000 PSI. But again, this would be for elephant only............ I actually used the lighter 450 gr Solids at 2400 fps with 96/X-Terminator for 57000 PSI for buffalo after taking a hit with the 410 Raptors at 2520 fps..... massive destruction........ I also have a Myrtle Stocked 500 B&M........

It is a joint effort, cartridge, rifle and remember, the Bullet Does all the Heavy Lifting, choose the bullet wisely, and the cartridge/rifle can perform as designed.

 

[Luvthunt]

Norma 550 gr in 458 Lott

 

[analog_peninsula]

The readily available factory ammo component is a big one for me. I don’t reload, like the convenience of buying it off the shelf.

That makes sense. It’s a shame A2 is no more as they served a very useful niche in the firearms ecosystem.

 

[neilw]

The 458 SABI might fit the bill. Its a 500 Jeffery necked down to a 458.

Only made by Sabi Rifles/Magnum Arm in Nelspruit in South Africa though.

 

[colorado]

Heym used to make a bolt action rifle in 500 NE Don't think they do anymore


Manufactured By: HEYM AG
.338 Lapua Mag. (disc.), .375 H&H, .378 Wby. Mag. (disc.), .404 Jeffery (disc. 1992, reintroduced), .416 Rigby, .450 Ackley (disc.), .450 Rigby, .458 Win. Mag., .458 Lott, .460 Wby. Mag., .500 NE (new 1994), .500 A-Square (disc.), or .505 Gibbs (disc.) cal., double square bridge Mauser action, express sights, Timney single trigger, available in right or left hand. New 1989.

 

[Aussie_Hunter]

Mate the amount of time and money spent on looking for obscure cartridges, instead you could buy some basic reloading gear and reload for anything and everything you could ever want.

 

[Dewald]

I used to shoot 550gr and 600gr in my Lott. I suppose both the .458 3” express and the .460 G&A would also work with somewhat less chamber pressure.

 

[BigGame]

500 A-SQUARE

 

[Riflecrank]

Mate the amount of time and money spent on looking for obscure cartridges, instead you could buy some basic reloading gear and reload for anything and everything you could ever want.

Aye !!!

The simple SAAMI .458 WinMag will meet all your requirements if you will handload !!!
Allow the COL to exceed 3.340" by just a wee bit,
and allow the pressure to go as high as they allow the SAAMI .458 Lott MAP.
In fact if you just put a SAAMI-chambered .458 WinMag into a 3.6"-magazined rifle action,
and load it to .458 Lott COL and MAP,
use the max .458 Lott loads for starters and work up, or down, from there, you are done.
The throat on the SAAMI .458 WinMag allows it to be loaded to .458 WM+ levels that will beat the
tighty-shorty-throated .458 Lott.
The .458 WM+ will have higher velocity or lower pressures or both.

Before I gained this common sense, I experimented with the .500 A-Square X 2 rifles, and three other 50-cal wildcats of my own design, also X 2 rifles each.
My favorite 50-cal after all is said and done is the .500 Mbogo 3-Inch,
based on basic cylindrical .416 Rigby brass left long and necked down to .510 caliber.
It is a few grains of water bigger than a .500 NE 3" and a few grains smaller than the 500 Jeffery.

My starting load for the 500 Mbogo (second rifle) was 100 grains of H4895 with 570-grain XLC or TSX.
I loaded 20 rounds of that for last weekend's Western KY DR&BB Shoot, last Saturday.
Only 9 were fired there.
The remaining 11 were chronographed with a Garmin Xero the next day, last Sunday.

MV average from 23" barrel = 2258.4 fps
Std.Dev. for those 11 shots = 7.8 fps
Range temperature = 59*F

That'll do ! Excellent when the Std.Dev. in fps is less than the number of shots fired.

Like a bolt action "500 Rimless NE 3-Inch" of sorts.
With higher velocity or lower pressure or both compared to the 500 NE 3-Inch.

H4895 is pretty temperature insensitive, good Thermo-Ballistic-Independence (TBI).
I can use it for reduced loads with no filler or compressed maximum loads.
That is like from 60% of net fill to 110% loading ratio, if I dare.

My Norma 500 Jeffery brass has about 161 grains H20 gross.
My Quality Cartridge 500 Mbogo brass has about 156 grains H2O gross.

Here is a listing of algorithm-calculated "relative" case capacities according to the RCBS
CARTRIDGE DESIGNER TOOL, gross water capacity in grains:

505 Gibbs ................................. 186.3
500 Jeffery ............................... 158.8
50-140 Sharps 3.25-Inch .... 157.3
500 Mbogo 3-Inch ................ 153.5 (my wildcat)
500 NE 3-Inch ......................... 147.4
500 A-Square .......................... 146.8
500 Bateleur 2.7-Inch ........... 136.3 (my wildcat)
12.7 x 68 mm Magnum ....... 133.4 (my wildcat)
495 A-Square .......................... 133.1
500 Van Horn Express .......... 129.7

 

[Riflecrank]

Here are the 500 Jeffery and 500 Mbogo drawings from the RCBS tool used for listing above:

 

[Riflecrank]

My culmination of 25 years of .50-caliber questing, ended with
a 500 Jeffery shop mule started in 2003 and completed in 2024,
except for stock painting with truck bed coat yet to be done,
just a cosmetic job.
Meanwhile I killed a cape buffalo with 500 Mbogo The First in 2010:

500 Mbogo No. 2 :

Here is 500 Mbogo No. 2 with shorter barrel:

or with less bulky scope:

 

[Riflecrank]

The accuracy load at 2654 fps (5-yard vel.) impacting cape buffalo at about 50 to 70 yards:

The buffalo bucked upward on bullet impact, ran 50 yards, away from us, and died.

What I really need is a .458 Winchester Magnum built like 500 Mbogo No. 2,
but with a skinnier barrel with a .45-bore hole for same weight,
9 lbs 3.6 oz unloaded.
Gentle in my old age, even if capable of all that he OP requested.

 

[Riflecrank]

Here is how the 500 Mbogo has greater net case capacity than the 500 Jeffery.
Since the CIP 500 Jeffery has such a short, leade-only throat, it can only be loaded,
with the 450-gr GSC HV and the 570-grain TSX,
like this:

Well, not quite no throat, it does have a short and tight leade from the case mouth into the rifling, that is a few thousandths of an inch of throat length.

Obviously the 500 Mbogo has a bit of parallel-sided free-bore.
I did it before I learned how great the SAAMI .458 Winchester Magnum throat was,
when I stopped listening to the Lottite propaganda.
If I had it to do over, I would scale up that throat from .458 caliber to .510 caliber for the 500 Mbogo.

The express sights are "regulated" for 570-grainer at 2260 fps.
Moon bead zeroed with wide V at 50 yards,
3/32" gold bead zeroed with first flip-up, flat-top, U-notch leaf at 50 yards.

With 4 rounds of ammo loaded, weight with express sights, no scope, is 9 lbs 13 oz:
Free recoil of first shot is 100.0 ft-lbs @ 25.6 fps.

Down to last round in rifle, rifle weighs 9 lbs 6 oz:
Free recoil of last shot is 104.6 ft-lbs @ 26.8 fps

Builds character for faultless speed and accuracy with the .458 Winchester Magnum.

 

[Northern Shooter]

Here is how the 500 Mbogo has greater net case capacity than the 500 Jeffery.
Since the CIP 500 Jeffery has such a short, leade-only throat, it can only be loaded,
with the 450-gr GSC HV and the 570-grain TSX,
like this:

View attachment 642437


View attachment 642438

View attachment 642439

View attachment 642440

View attachment 642441

View attachment 642442
Well, not quite no throat, it does have a short and tight leade from the case mouth into the rifling, that is a few thousandths of an inch of throat length.

Obviously the 500 Mbogo has a bit of parallel-sided free-bore.
I did it before I learned how great the SAAMI .458 Winchester Magnum throat was,
when I stopped listening to the Lottite propaganda.
If I had it to do over, I would scale up that throat from .458 caliber to .510 caliber for the 500 Mbogo.

The express sights are "regulated" for 570-grainer at 2260 fps.
Moon bead zeroed with wide V at 50 yards,
3/32" gold bead zeroed with first flip-up, flat-top, U-notch leaf at 50 yards.

With 4 rounds of ammo loaded, weight with express sights, no scope, is 9 lbs 13 oz:
Free recoil of first shot is 100.0 ft-lbs @ 25.6 fps.

Down to last round in rifle, rifle weighs 9 lbs 6 oz:
Free recoil of last shot is 104.6 ft-lbs @ 26.8 fps

Builds character for faultless speed and accuracy with the .458 Winchester Magnum.

Appreciate the feedback, you clearly know what you’re talking about and I’ve always enjoyed your posts regarding the potential of the 458WM with the 458WM+.

I’m personally pretty content with sticking with factory rifles and ammunition, I don’t know where I’d find the time to reload. If and when I decide to step up from my 458 WM / 470NE I’m pretty sure I’ll go with a 450 Rigby as I am looking at both the M98 and Rigby Big Game as my next bolt action.

I’m curious if you have calculated the recoil values for all your 50cal rifles with the loads above?