Hello

Does anybody have drawing and dimentions of the 585 Nyati case. What is the rim diameter?

Thanks
Mark

2.8 case length, .640 ish rim diameter, but can be .590/.595

http://www.470mbogo.com/BigBoreCompendium/#585Nyati

Thanks Jeff

Do you know what rim diameter is on the horneber and bertram cases?

Thanks
Mark

Mark,

horneber specs

George

converting those millimeters to inches, divide by 25.4,
16.20 mm rim diameter = .638"
16.72 mm head diameter = .658"

The Nyati looks like a VERY nice calibre.

And just able to be squeezed into a CZ. If they can do a 505 Gibbs, they can do a Nyati.

My cause for hesitation is that I like using a cartridge for its capacity and don't like to have a 4-liter engine in a little car driving 55 mph. So I figure that the Nyati is good for at least 9000 to 10000 foot pounds, or more. So there is not a lot of point in building one only to load it to 7000 to 8000 foot pounds.

Something like the 585 Short Hubel Express at 7000 ftlbs.

I vaguely recall some variations that caused problems with the .585 Nyati.
Most problematic: neck diameters of chamber, brass, reloading die
Less problematic: variations in rim diameter and brass length
It never was quite as well known and standardized as the 577 Tyrannosaur.
But it will do much the same thing as the 577T,
as long as you mind your P's and Q's in getting the rifle, brass and reloading dies to be compatible.

The Bertram brass I have measured has a rim and head diameter that is just .002" below the "supposed" max specs listed above.
Very good.
It has headstamp:

585 NYATI
(primer hole)
# BB #

(# = hopping kangaroo figure)
(not pictured at municion.org)
The Bertram brass is basic cylindrical that is 3.345" long.
Needs to be formed and cut to proper length.
I cannot vouch for either make of brass, Bertram or Horneber (nor HWM) regarding proper hardness.

Sumbuddy who know any pitfalls of .585 Nyati?

Was this not a calibre/cartridge thought of/invented by Ross Seyfried? I seem to remember reading an article by him a long time ago about this. Please correct me if I am wrong.

This is my 585 Nyati on a Weatherby action built by SSK. Feeds and cycles great! Off the bench it will do an inch to inch and half. I have 160 case that are Asquare 577 Nitro with the rims turned to the same as a 460WBY that came with the gun. But I would like to try the bertram brass to see if it will fit the bolt face.

Mark

quote:

Originally posted by Esskay:
Was this not a calibre/cartridge thought of/invented by Ross Seyfried? I seem to remember reading an article by him a long time ago about this. Please correct me if I am wrong.

You are correct.

George

quote:

Originally posted by Coloradoyaler:
... I would like to try the bertram brass to see if it will fit the bolt face.

Mark

It will not.
Bertram advertised the case I am talking about as:

585 NYATI 3" BASE
505 RIM ON 577 CASE
Stamped 585 Nyati

But the cases are actually 3.345" long, straight cylinder basic, yes mildly rebated to .505 Gibbs rim.
You have the more severely rebated case, one of the .585 Nyati variants. 2.8" or 3" lengths also exist.
That makes 4 different possible combinations for this cartridge.
It would take a lot of lathe work to put your rim size on the Bertram case.

The big article by Ross Seyfried about his .585 Nyati creation was in GUNS & AMMO/DECEMBER 1991 pp. 56-69
The final paragraph by Ross on pg. 69:

"Is there a purpose? Probably not, but
there is a certain faction of us
who like real horsepower. A Volkswagen beetle
will get us there; a 5-liter Mustang does it
with panache. My own rifle is an exercise
in futility. It is exquisite, too nice to
scratch, but I will carry it against Nyati at
least once. It now belongs to that rare
combination of human endeavors that
few things other than arms ever
achieve--functional high art. Hopefully it
is nice enough to be preserved, to last in-
to the sad days when a young man will
ask, 'What was a Cape buffalo?' If its art
and power can make a statement that
answers the question, then the whole ef-
fort will have been worthwhile."

I wonder what bullet that is in the end of that case?



M

Thanks Guys!

The nice thing is I beleive the 160 rounds of brass I have will last quite awhile. I also talked with a gunsmith who will turn the 577 brass or the bertram brass for me. I have plans to take a few buffalo with it.

Thanks Again
Mark

Lots of Bertram brass is quite soft. It will work, just be careful with it.

The 585 Nyati is NOT by ANY STRETCH a great cartridge can and has been a major problem for many shooters and almost everyone who has ever built one.Yes Ross Seyfried invented it but he used .577 NE brass as the basis for the case, and neck reamed as well as converted the rim to a rimless case. His rims varied from .590-.640. Depending on who made the brass cases, and what action it was built for. Some of these guns were made on M98 actions! Unless you are a machinist you will not be able to duplicate these cases which were the basis for his reamer design. The necks on his cases were at best <0.008 thick. The case is also not at all easy to make feed , with a real bad tendency to want to porpoise and of course requires the bolt face to be opened up to the maximal limit. I have a few of Ross's original cases and I also have a much modified 585 Nyati that I built myself. Quite a few folks here on AR have shot it. Ross Sigfried's original reamer dimensions, for which some companies still stock reamers is not correct and produces a neck too small for either currently available Bertram or Horneber brass. You load a bullet and you can't close the bolt. Or worse, if the bolt does close ,there is no room to release the bullet resulting in extremely high pressure spikes. If you use soft Bertram brass in a gun with a too tight neck, the case will stick solid in the action and you will have to hammer it out! In the early 2000's I had Horneber make a special run of 3000 pieces of Nyati brass, made to my dimensions,i.e 2.8 inch case and .640 rim. for a group of about 20 of us here on the AR website, all of whom had the same brass issues with the Nyati which helped the situation alot. I still have a few hundred cases from this run. Nevertheless,If you have a chamber cut with a Seyfried dimensioned reamer, and even if you use a cerrosafe mold and then neck trim far enough to get cases to fit properly, the neck may still winds up so thin it collapses even with the Horneber brass. This all can be corrected but requires a custom neck reamer, and extreme care needs to be used so as to not wind up with a oblong chamber. There are many guns out there with this problem. I had corrected reamers made by both JGS and PTG and they were both well aware of the issue.I believe these corrected reamers have been available to the public for at least 10 years now. The Nyati fell out of favor with DGR shooters over 15 years ago because of all these issues as well as the fact that only a handful of shooters could handle its recoil. All of these problems described above led me to the initial idea of the .600 OK many years ago. The .600OK solves all of the problems inherent in the Nyati and out performs it in every possible way. -Rob

I knew Rob could explain what those pesky variations were, but only Ross Seyfried could explain why.

Rob

To small of a neck. Are you talking about outside neck diameter and what size should it be?

Thank for all the input!

How about brass life? Has anyone shot one enough to determine how hard this cartridge is on case life?

Thanks
Mark

I don't know Mark but that 585 just always seems to be problematic. Unless you're married to that round, a 600 Overkills make a lot of sense. Easy to load & get it going. If recoil's an issue, load it with 700-800gr expanding solids & drive them lengthwise through anything.

I've always designed my chamber reamers to produce chamber necks at least 0.003-0.005 larger than the diameter of a case loaded with a bullet (in order to assure that the case can easily release the bullet). A cerrosafe mold should be done to confirm this. A friend of mine used to load 50 Nyati rounds to find 5 that would even chamber in his gun! Bad Idea, as he had to hammer a buch of stuck cases out of the gun! Its best to check this dimension with different brass as they vary in wall thickness between manufacturers, between lots and often an individual case varies itself in thickness. This is why benchrest case necks are uniformed for obtaining minimum pressure variability. I dont ever neck turn DGR cases as I actually want them to have a degree of slop for reliability. I suspect Ross had someone make him some cases from various old .577 NE brass, then made a reamer that worked with those cases. Later when Bertram made cases using thier typical methods out of much softer brass, the cases just would not fit. Its kinda like a chase your tail game.
The best NYATI brass out there is the Horneber stuff I had made in the 2000's. That Horneber brass was made with uniformly reduced neck diameter brass and works well in most guns. I've reloaded Horneber NYATI brass 5-7 times ( neck sizing only) successfully. Bertram , once or twice if your lucky ( avoid fll length sizing and setting the shoulder back at all). My gun was built on a CZ550 and was a huge pain. It feeds OK now, but took a inordinate amout of effort and some mag box tricks to get to work. .600OK brass seems to last forever, like most straight walled cases. At $3 a pop case life is important in my view.
You tend to see .585 NYATI's for sale reasonably often, They tend to show no evidence of ever being fired or maybe just once! -Rob

Thanks!

Rob

I don't have any cerrosafe. My fired case mike out at .608 vs unfired at .605. Does this sound about right? What I am trying to establish is would it be better to machine brass from 577 brass or can I just buy the bertram 585 and just machine the rims. And, Would either or both require neck reaming? I am trying to keep options open for brass in the future.

Also, who is doing 600ok barreling?

Thanks Again
Mark

Well it sounds like it's opening up and chambering ok. I'd try and source some Horneber Nyati brass and turn the rims if you have too. You might also consider having a gunsmith open up the boltface to std NYATI dimensions, but then your current brass would be useless. I had the same sticky case problems with the A square brass I had as I did with the Bertram stuff. If all else fails I have some Horneber brass available.-Rob

fyi -- asquare nyati brass IS bertram

Jeffe- I heard that was the case but never bothered to confirm it. Both A Square marked and Bertrum brass would stick badly at 2400fps ,at least in my gun. My friends gun had a rough chamber and the cases would stick at any speed over 2100.-Rob

Rob

The bolt face on my 585 is an enclosed bolt face as is the 460 wby. I measured the bolt and opening it up would only leave .010 rim on the bolt.

I might take you up on the brass offer! How many do you want to sell and how much?

Rob and all I do thank you for your help getting me lined out with this rifle!

Sincerely,
Mark

Mark-PM me and we will work it out. Yes the rim will be very thin if you open up the boltface. People have done it and had no problems with CZ 550 actions. You will need to do it anyway if you ever consider rebarrelling to a .600OK which of course has the same Rim diameter as the 585 NYATI. No one I know of has ever had a problem with those thin rims but it certainly is a valid concern. The increased bolt diameter of the Montana Arms PH action was designed specifically to eliminate this problem. One thing to remember is if you have NYATI rims turned down, make sure the backside of the rim is beveled or you may have problems with the extractor jamming. -Rob

Rob

Sent you a PM

Thanks
Mark

quote:

The necks on his cases were at best <0.008 thick. -Rob

That sounds very thin. I thought 0.011 to 0.012 would be more normal. Can anyone comment?