By midbore, I mean .585 to .620 diameter of big

bore cases of regular length(2.8 to 3.2 in)--





A-Bottleneck cases--



1-585 Nyati-Base .660--Sh .650--Length 2.8 & 3.0



2-585 AHR--Between Nyati and T-REX I think



3-585 Gehringer-Like Nyati--3.0 long.



4-577 T REX--Base .688 --Sh .673--Length 2.99



5-585 African--Base .685--Sh .670 --Length 3.0



6-585 Van Horn and 585 Wells early versions

and built similiar to Nyati.





B-Rimmed cases--



1-577 NE --Base--.660--No shoulder--Length 3.0



2-600 NE --Base---.697--No shoulder--Length 3.0



3-600 JDJ--Base--.660--No shoulder--Length 3.0





C-Belted straight cases-



1-600 OK--Base .658--No shoulder--Length 3.0 & 3.2





D- The best for the average Joe to set up in an

economical rifle, with case design allowing the most

reloads, simplest chambering reamers, simplest reloading

dies, and greatest power---600 OK----And I ain't

buttering up Rob.In fact the original specs for the

OK had the sides to straight,with brass thicker in

the neck than needed, but when they got back from

Deiter they had the right thickness and perfect taper.

The heading says regular length cases,

and we all know my super long ones are the best

overall..HahHa..Boy this hobby is fun...Ed.



E-Any other cartridges in this category please

post info.Thanks in advance-Ed.

Ed,
How old were the van horn and Wells 585 calibres?
I remember hearing about them now that you mention them.

Karl.

The first of these sort of calibres I remember reading about was the 475 LTD which was Lott Tanner Dinosaur....if memory is working

That was a 577 made rimless and necked to 475 with Jack Lott so today it would be a 475/585 Nyati.

Mike

Ed- There are other things to consider. The rim diameter of the original 585 NYATI was .590 which is the same as Karl's 585 Gehringer( same case rim as the 416 Rigby). Severely rebatted rimmed cartridges often display serious feeding problems particularily when stroked quickly. My original attempts at a Seyfreid 585 Nyati displayed enormous feeding problems compounded by the poor neck design and the use of crappy Bertram Brass. The classic problem with rebated rimmed cartridges was the porpose and bolt override. That's why most successful rifles with cartridges like this require single stack magazines. The .600 Ok-1 has a slightly rebatted case rim of .640 as it was first designed for the CZ550 Bolt diameter .700. The .600 OK-2 which is designed for the GMA action has a full size rim. In addition all the OK series cartridges have a bevel on the cartridge rim to facilitate feeding. The OK's work through std magazine's and don't require a single stack. I've been quite pleased in fact at how the cartridges line up against the right and left walls of the GMA action and slide smoothly into the chamber.-Rob

Rob--And that is why I figured that the case needed the
little more slant that it finally came with,after Deiter made them, to help feeding as well as cut the chances
of the case sticking, if load got to higher pressures in hot weather.When you get a chance send me the load info
on the H-414. You typed wrong figures for Nyati base.Base was .660 as Ross made case from 577 NE.The base not the rim.
Ross and other wildcatters made the rims all over the size scale to adapt to different bolts.The OK is a winning case design and now with knowledge available on getting them to
work in various actions, it's going to take off.Ed.

Mike- Yes that was an early one that was done on a
577 case with the rim turned off.At that time there was
quite a few guys playing with 577 brass, making them rimless, for different ideas.

Mike, what is the minor diameter of a Wea Mark Five
bolt, IE at the base of the lugs.Never measured one.Ed

Karl- They were a 3-4 years before Ross did his if I remember right.Never were out in public like Ross did
the Nyati.He has done the most in the gun realm to help
push big bores, and the Nyati was the catalyst.Along with
Bruce willing to make cases from scratch.Ed.

Ed,

I will get one measured for you in the next day or two. I am gunless until about May.

But I know what you are getting at and the answer is that in my opinion the 378 case rim is already at the limit. Well you could go a bit bigger but if you dropped the bolt..well enough said...just make sure you drop into water But they are slightly bigger than a Rem 700.

Apart from dropping the bolt any of those counterbored bolt heads that were made super thin might present some problems with an overload.

One other cartride you might like to add to your list is another 585 Nyati that was made in Victoria Australia. This was the 500 Jeffery expanded out to 585 and headspacing on the mouth like a 30 M1 Carbine case.

Mike

Mike--What was the name of the wildcat 585 built on
Jeffrey case.I already figured out the dimensions,
if it was built on a full length expanded case.
It definately would be straight side.And in my big bore
way of thinking makes more sense than a 260 Rem.Ha Hah.
I have notebooks full of all this stuff ,I write down.
The reason I ask about Mark Five is I know it has major diameter of .840(fatbolt)from the bolt rifle book.And if minor diameter is big enough it will handle the OK case with
rebated rim.And if it would work, just make sure all
lugs are seated.I would have put my wildcats in Wea if I had one.Ed.

Ed- Sorry, I meant case rim. not base. By the way I've seen and handled the first 585 Nyati sterling Davenport made for Ross Seyfried. It was made on a M98 mauser action with a schuler single stack mag and used a .590 Rim made from a 577 NE case. The 585 Nyati then was changed to a .640 Rim and both 2.8 and 3.0 inch versions were developed. Apparantly by a number of different people. The final Seyfried version ( I have his reamer print) used the .640 rim but had a neck diameter too tight for even Bertram brass to work.
By the way, 158 grs of H414 has been my top load in the .600OK-1 so far. I am not seeing any significant belt expansion ( < .001), sticky extraction or primer problems and more importantly I have unscrewed the barrel on my GMA actioned gun and carefully measured the action face to locking lug distance for any signs of bolt set back. No change so far. One advantage of doing your own work is that I have all the action dimensions carefully recorded and can readily determine if problems are occuring. -Rob

Ed,



I think it was called 585 Nytati. NitroX might be able to get that confirmed as I think he is a member of The Australian Big Game Rifle Club and most of this sort of stuff in Victoria all has a relationship with that club. NitroX runs the site www.nitroexpress.com



In fact I have a feeling that the 585/500 might have been before Seyfried's 585 Nyati. There is a suprising amount of big bore activity in Australia considering our small population and I think one of the reasons is because for us our counterpartb of your woodchuck shooting is roos, pigs and goats.



I have emailed a mate of mine who is a poster on this forum, Charlie Murray, to do a measurement for you. In fact he can do German, Japanese and USA made.



Mike

Mike,

I remember when I was researching to do mine there was a '585 Nyati' bolt action for sale down in Victoria for about $5000. This was the only one I could find before mine.

I wonder if this was the 500/585 you are talking about..



Ed, since we are getting obscure, in about 1999 JD Jones told me of a shortened 577 nitro case he could get to work through a Ruger. Not sure if he meant 585 nyati or his own creation.





Karl.

Karl-I think it was his creation.And the #1 has been done in 577.There have been a lot of guys that necked 577 brass for all kinds of use, even some
pistol cartridges.Some they shortened by half.How is
your computer working on this site.A lot here are having trouble.Ed.

Ed,

The Weatherby bolt nose is .72"

Mike

Mike-That means it would be big enough to do anything that
a .700 diameter bolt could do.Like Nyati style or the OK.
Wea with the lugs seated is fine.Lug recesses by the way are
on top and on each side, thus allowing more room for a ramp to feed cases into chamber, without affecting lug receeses.
Possibilities that can get more folks involved in
making the OK famous, as there are lots of folks who love
shouldered cases, hate belted cases, especially straight,
even though straight is better, who will promote and wildcat the Nyati style.Which is fine, folks doing what
they like either way promotes big bores.Anything big bore
is much better than 260 Rem syndrome.(that being to introduce junk, in caliber ranges with 5 dozen chamberings already)....Ed.

Ed,

Yes, there are no lug recesses on the bottom of the action. That is one of the things that allowed Wby to have a Rem 700 action length but with a long magazine.

A second hand shot out 30/378 Synthetic, plus McMillan stock (they are bigger in the forend as they will take the 460)and a rebarrel would have to be one of the easiest and cheapest way to the 500 A2. Mitch, who use to be forum leader here before George, has a 500 A2 that was a rebarreled 460.

But if I was interested in having a 585 Nyati type calibre I would find the CZ a more appealing action than the Wby. For me and I suspect many others, the Weatherby rifle and Weatherby calibres simply go together. 500 A2 is a little bit different as it is carrying the 460 headstamp.

Although it would be a super easy conversion I could not imagine having a 500 Jeffery in a Wby Mark V To me, that would be about as unattractive as having a classic Mauser style rifle in 30/378

By the way, a 460 Wby compared to Robgunbuliders 600 OK is virtually identical to the differences between a 270 Win and 375 H&H. 458/620*375 = 277016. Actually on powder capacity and pressure of load used it is probably like a 270 Winchester compared to a 375 RUM that has been loaded back to maximum H&H ballistics.

Mike

Mike-The Jeffrey goes with Mauser I guess.But I am not sentimental.To me the WEA ACTION,speaks big bore,And if set up right so that apparent strength is there, IE,lugs bearing.It is an action that to me seems great to me for big bores.Not the bad stock design, that kicks you silly, throw that away.The action..It is perfect for the 550 Mag built in WEa brass even more so than 500 A-SQ.
And a great action for the OK.Singlestack mag.Regular classic heavy duty stock.Gun weighted.Muzzle brake if you want..I am an action person,IE see how the action fits
different cases,
names and sentmentality don't matter as long as built safe.
I mean the OK can be built fine on a 116 Savage that they
sell for Rum cases.Easier than most as they are long.Ed.

Ed,

The Weaterby stock and recoil proves without doubt that we shooters are built different. I personally hate real straight stocks and would take the Wby stock everytime.

As a matter of interest we have a fibre glass stock maker in Australia called Corporal Trading. PC has one on his CZ/585. These are an expensive stock. The maker of the stocks recommends his "Wby style" for all big kickers.

While over the last 30 years I have had a lot of Mark Vs and now have some coming via their custom shop (all steel bottom metal and bit better wood, no big thing as such) I have never really seen the Wby as the ideal action. As a total package I obviously like them a lot. Wby rifles remind me of a General Motors car we out have called the HSV Commodore. That would be similar to what you might have as a factory hotted up engine and handling Chev or something.

I think one potential problems with a Wby action and any of these big wildcats (or 500 J or 505 Gibbs)that generally have soft brass....is the poor primary extraction caused by the 54* bolt lift. On the plus side for calibres like 500 A2 conversion of say a 300 Wby would be many times easier than sayong converting a CZ in 300 Win etc. Wbys do not use the action rails for anything except to hold the front and the rear of the action together

Mike

Mike-I have some here interested in converting to 550MAG,
based on 460 case. No dimension problems like what may happen with Jeffrey.One case and chamber size and die size for 550 Mag.RNS is making sure it is all the same with
reamer and die makers.Some of you WEA guys have got to
go with 550 MAG.Make it and the forum famous.Ed.

Ed,

Well i know where I can get a cheap Japanese 416 Wby. This rifle has really been all over town and has a McMillan stock....one of those stocks they use to mkae that look like woodgrain. A mate of mine bought the rifle when the 416 came out and then a bit a later had a 338/378 fitted (when that calibre was still a wildcat)...then I got the rifle and parted with sometime ago.

By the way, Geoff McDonald the maker of Woodleighs had/has something he calls the 540 McDonalds (I think it is 540) which is the 460 case straightened out.

For 550 Mag what is groove diamter.
Bullets????
Barrels??
Dies and reamer??

I might be interested as I have been toying around with the idea of something a bit different to the upgraded factory Weatherbys coming. I have a pair of upgraded 378s that should arrive around May. There are a pair of 30/378s to be ordered. One an upgraded Accumark and the other upgraded Deluxe. I am just deciding at the moment which 30/378 to order first (50% deposit to the import agent) and that will probably be next week. Then there is also an upgraded 460 Deluxe and a standard 270 Win Ultra Light.

A 550 might make an interesting paper patch calibre. Cast bullets, gas checks???

If it is 550 bullet diameter then a couple of quick calculations show that if loaded to the same pressure as a 460 requires to do 2500 f/s with 500 grainers then the 550 should do as follows:

600 grains 2520 f/s
700 grains 2335 f/s
750 grains 2225 f/s

Assuming if course equally suitable powder for the 550.

Mike

Ed,

Actually to do something like the 550 I would skip the Japanes 416 I mentioned above and start with a Made in USA 30 or 338/378 so as to have everything all nice and new and also consistency with all the actions being Made in USA.

Mike