This one is a doozie.
The Good Doctor John Mabayoje, of Nigeria, designed it.
Edd Woslum executed the plan to perfection, and wrote the article, pp 45-47 of the journal:



CZ 550 Magnum action with new safety, trigger job (looks like the factory CZ), and take-down job.
A "taken-down" picture of the mechanism is in the article.
3-pound trigger pull.
No. 6 sporter barrel by Krieger.
Stock is custom made of African obeche wood, 26-lpi checkering.
NECG sights, barrel band sling base, and sling base inletted into buttstock.
Talley rings.
1x-4x Swarovski scope.
11.25 pounds as pictured.
No mention of barrel length.
Reported 2400 fps with 535-grain TSX, and 2350 with the 570-grain banded solids, Barnes bullets.

Edd Woslum can build a rifle.
He is also the creator of the .400 Tembo wildcat.

Four Fifties:
500 A2, 500 Mbogo, 500 Jeffery, .505 Gibbs:



King of the Heap, 500 Mbogo:





This 500 Mbogo shopmule needs some work ... maybe I ought to start over from scratch.
The gunsmith just finished the first year of medical school and might be able to turn out another one in the next two months.

"GREAT" hunting bullets available for the "Fast Fifties":
GSC HVs and FNs if you can get the diameters to match your barrel grooves, in the weights you want.
Hornady's are coming, 570-grainers of .510" and maybe tougher than Woodleighs?


Add the 500 Nitro Express to the mix, for a "Big Five of Fifties"
500 NE
500 A2
500 Mbogo
500 Jeffery
.505 Gibbs
... at least one of them is well served by Woodleighs.

Barnes TSXs may be usable, but they are closer to .508" diameter than .510".

Looks like Edd Woslum machined the CZ bases into Talley bases for use of the standard Talley rings with levers on the left side.
Not the Talley-CZ-specific rings.

New bolt handle too.

I think I will rebarrel this BRNO from .510 JAB to 500 Mbogo:



And use these low Warne Rings on it:



That works.
No plans for a take-down ... yet.

RL-17 is the most amazing powder in QuickLOAD for the 500 Mbogo.
All bullet weights from 450 grains to 600 grains give top velocities with RL-17.

A new powder, for a new cartridge.
Temperature variability greater than the Hodgdon Extreme line is my only concern there.
Will see how it turns out from summer to winter testing.
But first to see if the QuickLOAD predictions for RL-17 are anywhere near reality ... in the summertime heat.

You've hijacked your own post!

Interesting rifle on that cover and the wood looks pretty good.

I'm going to have to find an issue! Any load data in the article?




Chuck

Charles,
Right!
The blog continues.

Chuck,
They are going by the A-Square manual, Any Shot You Want.
That is a good book with pressure tested data.
Best Thing Art Alphin ever did, besides coming up with the best name ever for a cartridge: "577 Tyrannosaur"

500 Jeffery top loads there:
570-grain A-Square Monolithic Solid .510" bullet diameter
26" barrel of 1:10" twist (not a Krieger!)
A-Square case
CCI-250 primer

H4895 104.0 grains ... 2348 fps ... 42,100 CUP
RL-15 105.0 grains ... 2291 fps ... 39,800 CUP

A-Square does not have any 535-grain data, but Edd just pushed that one to 2400 fps, no barrel length or load specified.
No loading data in the PS article except the reference to the manual.

I have "Any Shot You Want", it is a very good book. I also have the Barnes reloader manual #4. Most of the loads I find on the internet tend to be on the warm side compared to the manuals. I think that's because they're loading to modern pressures which the CZ can handle rather than the 40,000 PSI in my manuals.

I'm sure you've seen this article online, if not, it's worth a read. This is part 2 of 4 with their load data which I think is on the warm side ...

http://www.realguns.com/archives/157.htm

Regards,

Chuck

Oops, my bad,
The A-Square load pressures were CUP, not psi and fps, will correct above.

The max average pressures for 500 Jeffery, according to A-Square:

41,364 CUP or
47,170 Piezo PSI

CIP max average pressure for 500 Jeffery:

3300 Bar = 47,850 psi

Thanks for that link,
I was reading that once, never got through it all, will go back to it. Joe does nice work.

Yes, the CZ can handle up to 3800 bar or about 55,000 PSI, even in the .505 Gibbs.
So it makes sense that it can handle more than that in the 500 Jeffery,
or way more than 60,000 psi in the 500 Mbogo.
The brass is the limiting factor, or your shoulder.

Highjack still on.

http://www.realguns.com/archives/157.htm

chuck375,
I think Joe did some more good work there.
His Bertram brass cases measured 158 grains of water gross.
He noted the Barnes TSX bullets to be .508", but gave good results.
He estimated pressures should be kept below 57,000 psi in a CZ 550 Magnum.
I think he succeeded well in that.
His loads are "moderate" IMHO.
With the 500 Mbogo being only three grains smaller than the 500 Jeffery cases used by Joe,
his data will transfer directly to the 500 Mbogo.
This will produce only slightly higher pressure and velocity in the 500 Mbogo,
less need for filler volume with the faster powders,
and less than 60K PSI is fine and dandy in the 500 Mbogo.
The .375 H&H has higher pressures than that.

The self highjack continues.

Agree Rip, though I think my shoulder and head will be the limiting factor, not pressure when it comes to the 570g Barnes bullets. I'm thinking 2300 fps is a reasonable maximum for me. It may well be 2150 fps!

Regards as always,

Chuck