.585 Nyati

[Lee Martin]

As some of you know I’ve been planning a .600 Overkill build since 2011. Every winter I was bent on putting one together. And every winter some other gun took center stage. Well this week I’m finishing an express rifle and it inspired me to move ahead (that rifle will be posted here shortly). I only have a few pieces of Overkill brass so step one was to secure more. Regrettably four years of procrastination came back to bite me. In that time Jamison, the shell manufacturer, went out of business. CapTech International took over their operation but have no plans to punch .600 OK. It seems the brass blanks and forming process are a headache and there isn’t enough demand. Custombrass.com is also out of stock making American Hunting Rifles my last resort. They chamber the round and sold empties for $530 a 100. Expensive but I was willing to pay that to get going.  Recently I spoke with owner Wayne Jacobson and he informed me they don’t offer components anymore. All remaining brass is saved for customer builds. I can’t say I blame them. Without ammunition who would drop $10,000 on a .600?

Some brief history on the .600 Overkill. It was designed by Dr. Rob Garnick of Nevada in the early 2000’s. The goal was to duplicate or exceed the .600 Nitro in a bolt action. By turning the rim, cutting an extractor groove, and headspacing off a swaged belt they modernized the old Nitro. And boy did they modernize it. 900 grain bullets are capable of 2,400 fps, which equates to 11,300 fpe. Un-braked recoil is in excess of 300 foot pounds from an 11 pound rifle. Four times that of full-house .458 Win Mag. And yes, you can separate shoulders and detach retinas at those levels. I’m quite aware of what I was getting into.

I was put on this path by Ross Seyfried’s .585 Nyati. He featured the wildcat in a 1991 issue of Guns & Ammo. Ever since that read twenty-four years ago I’ve wanted one (I’ll scan and share the article at a later date). In normal Seyfried fashion the piece was captivating and thorough. Enough to sell me on the conversion but like the Overkill no brass is a non-starter. By chance I was able to get 100 pieces of 3.0” unformed Nyati from Bertram. I thought I’d document the project for those that may be interested.

.600 Overkill (left), .585 Nyati (right):



The base receiver will be CZ’s massive Magnum 550. I’ll cover it plus other suitable actions as the thread progresses. The build will take some time and right now my target date is early 2016.  Dad is up to his neck in gun stuff so we won’t cut the reamer and dies. Instead I’ll get the finisher from JGS. Dies, both the 3-die set and case forming, will be ordered from CH-4D. Pac Nor rifles the blank in 1:18” twist and they’re four months out. Then there’s the stock, bullets, and a muzzle brake we’ll machine ourselves. Look for updates in the coming weeks.

-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[Markbo]

Whoo hooo! Look forward to it very much

[toroflow]

Detached retinas anyone?

[cmillard]

load development will be fun with that!

[kings6]

One shot of that baby and I would be on shoulder surgery number 5!

[grizzly]

Looking forward to seeing this build. I've always been fascinated by rifle like this. While I've not shot a handgun yet where I thought the recoil was uncomfortable I don't have much if any experience with even moderately heavy recoiling rifles. Hats off to guy that actually shoot guns like that without sustaining injury.

[cable]

Aug 19, 2015 19:48:34 GMT -5 toroflow said:

Detached retinas anyone?

Phil Shoemaker wrote about that starting to happen with him while firing one of these super monstrous rifles.

[Lee Martin]

Aug 20, 2015 8:44:20 GMT -5 grizzly said:

While I've not shot a handgun yet where I thought the recoil was uncomfortable I don't have much if any experience with even moderately heavy recoiling rifles. Hats off to guy that actually shoot guns like that without sustaining injury.

Hard recoiling rifles abuse the shooter way more than even the largest handguns. Unlike a revolver there isn’t 3 feet of air between you and the gun. Yes, your wrists and hands take punishment but do so under travel. With a rifle it all lands on your shoulder and face. And your wrists still get wrenched. It may surprise you but I’d rather shoot my .50 Alaskan BFR than our Alaskan Siamese Mauser. Fifty rounds of 585 grs @ 2,000 fps and I return with a headache and sore shoulder. The same holds for a .500 Maximum Ruger from the bench. I’ll take that any day over my .450 Ackley on bags.

We’ll be cautious with the Nyati though. If I’m going to launch 750 gr Woodleighs to 2,500 fps it’ll happen with a brake, mercury reduction, a sling, and 12 pounds of mass. On a lighter note I also designed an 840 gr cast with Mountain Molds. Plain base and out of lino it should do well at say 1,700 fps.

-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[cmillard]

lee, you are crazy. but that is why we like you. cant wait to follow this one too!

[cj3a]

Lee look here forums.accuratereloading.com/eve/forums/a/tpc/f/2711043/m/1071070312

[Fowler]

I know Seyfried decided pretty quick that this cartridge was too much of a good thing and backed it down from what it is capable of.

[bradshaw]

Lee.... reckon you'll want to document this baby. May want to have your father as corner man, certified sawbones. Have him tape you up----before shooting. Whereas the boxer tapes up to protect fingers and hands spreading under punch impact, your Old Man will tape you up like the Mummy----to prevent torso splitting!

Expect document will show a major look at the muzzle brake, with reference to German, American, and Russian research in this area.

One other item: consider double vertical pistol grips and a wide recoil pad hacked from a 4" sorbothane slab.
David Bradshaw

[Markbo]

"The .585 Nyati....

.....when Carpal Tunnel damage just isn't enough...."

[James]

just re-read the Seyfried article yesterday. Would love to see the finished rifle......

[nockhunter]

I remember that article, the recoil sucked the earmuffs right off of his head.

Mike