I have a 375 ultra mag that I love,it is one of the more accurate factory rifles I have had,300gr partition@2800fps,never over 1" @100yds with a 3 shot group and very consisent.The only thing it needs is a bigger diameter bullet say 458.I have a rem mag action sitting around and am thinking about necking up the ultra mag case to .458.Has anyone played with this caliber?I'm thinking about a 450gr X bullet@ close to 2600fps and a 500gr@ close to 2500fps,I believe that's about 100fps-150fps faster then the 458 lott.Any info would be great.
thanks

griz

There is a place called Ultracats or Ultra Cats. If search on the internet you will get their site. They have the reamers and dies for the lot from 6.5 to 458.

There is also a wildcat called the 460 G&A (Guns and Ammo) which is the 404 Improved necked up to 45 and that is essentially the 450 Ultra. Also, if go to Saeed's loading table page you will see 450 Vincent Long, which is another version of the 404 Improved necked upto 45.

Mike

The 458 Canadian Magnum is very similiar - rebated version of the 404 Jeffery and improved to the max. Might want to use a 40 or 45 degree shoulder for better headspacing, the Canadian uses a 30 degree shoulder. Don't scrimp on the neck length; you aren't going to be gaining much powder space if the bullet base is below the neck.

I find it really strange that the .450 vincent long, bypasses .460 Weatherby magnum, using only 104 gr. of powder compared to 120 gr.in the .460,,and the .460 Weatherby is larger,with more volume.
So my question would be ,were Vincent pushing it too far( was thinking of the fast powders)?
Maybe case design, powders and rifle allowed him to load a 500 gr.fmj to 2650 fps ?(even though i find it very strange that a case of less size bypassing the .460 !?
If one loaded hot with faster powders like longbob with imr-4320, it would have a velocity of 2650+ fps i think( long bob got 2685 fps with a 500 gr.fmj and 113 gr.imr-4320).

Griz

Why don't you neck it up to .423 with a 400 grain bullet? That would be a cool cartridge.

Per,

This is a recap of those loads.

460 Weatherby, 26" barrel, and muzzle brake (thank goodness!). 500 gr. Hornady FMJ.

IMR 4350

120.8 gr.
2546 fps
-0- Error
2591 fps

123 gr.
2646 fps
2659 fps
2661 fps

IMR 4320
107.8 gr.
2560 fps
2555 fps
2589 fps

113 gr.
2685 fps
2680 fps
2667 fps

Factory 500 gr. FMJ
2625 fps.

folks- some observations on the 460 wby-26inch barrel-wby brake!
1. IMR4350,500 gr Hornady crimped solidly,fed 215 primers
110 grs- 2440- no belt expansion
112 grs- 2485- no belt expansion
114.5 grs- 2513- no belt expansion
116.5 grs-2583- .002 belt expansion- same as factory- My max load!
118 grs-2621- .004 belt expansion, evidence of extractor marks,sticky extraction
I know others have obtained higher velocities but they apparantly don't crimp the bullets and load them out to just touch the lands ( won't feed through the box). Perhaps IMR4320 is a better powder, but be darn careful of this cartridge and attempts to push the 2700 fps barrier.- I'm a lil chicken here and when I see evidence of extractor marks and serious belt expansion I quit!
I also bet that the 458 ultamag is a super cartridge. It will work great in a Rem 700 unlike the 460 WBy and will beat my all time favorite Buff cartridge the 450 Ackley in a affordable rifle. I think a 458 Ultramag would be just the ticket for Africa ( push feed or not). This cartridge should be able to hit the magical 2400fps with a 500 gr bullet at much lower pressures than the 450 Ackley/lott/ watt crowd and avoids the over-velocity problems as well as action issues of the 460 wby. A super choice I believe.-Rob

[ 10-11-2002, 07:25: Message edited by: Robgunbuilder ]

Thanks, folks, and i'm really into the business of changing or convert my .416 Wby into .460 Wby.I''ll change barrel, and you are free to speak.How would you change this thing to get well beoynd 2600 fps !Robgunbuilder,help me out ?

Per577- I'd be happy to help you. Perhaps by E-mail! Just remember though that a 500 gr bullet at 2700 fps may be a Terrible combination to use for hunting! In Africa, all you hear from the PH's is reports of 460 WBY's giving terrible results on game due to the high velocity causing even solids to perform erratically. IMHO the 460 WBY is really at it's best in a M77 Ruger with three or four in the box at No more than 2400FPS with 500 gr Woodleighs! The WBY action is OK in my book, but why they chose to limit the mag capacity to two rounds is beyond me! Nothing that walks this Earth today will not be killed by this and the difference in your shooting ability due to reduced recoil will also help you.
If you just want velocity and don't care about using this on game, then load the bullets way out and don't crimp. Perhaps with IMR4320 you can beat the 2700 fps barrier ( but please Mike your cases at the belt and watch the number of times they are reloaded, quit at the first sign of ejector marks). If you want more velocity you will need more case capacity. I'd change cases at that point.
You could probably build a 3.0 inch version of the 585 NYATI in 45 caliber if you wanted that would exceed 2700 fps. By the time your done you could have bought a Tactical .50bmg for less money!
The 458 Ultramag in a Ruger M77 would be a slick African gun IMHO. I'd also use one in a Rem 700 anytime as long as there were more than two in the mag and one up the pipe. -Rob

Thanks Robgunbuilder !
I have really thought about the 3.0 inch Nyati which's called .585 Gehringer. That cartridge,will do 2600-2650 fps with a 750 gr. bullet,,so .460 Wby is the alternative(maybe .475 A&M Magnum).I was thinking about a 28 inch barrel without brake, like the Douglas SS custombarrel,what do you think,,and a fast twist, like 1 : 12,or 1:14 ?
I'm not sure about powders here in Norway ,but i think it's hard to get hands on imr-line of powders,, so i think maybe vvn-550(similiar to imr-4350), and vvn-540(like imr-4320,i'm not sure).There were a guy here who used 123 gr. of vvn-150, to get 2730 fps in his .475 A&M Mag. and 500 grainers( the only one to own a .475 A&M Magnum in Norway).

In the future i'm considering following cartridges; .585 Nyati,.505 Gibbs(heym),.585 Nyati Imp.,.577 T-rex,.620 Belted rimless.........or .600-50 BMG & .700-50 BMG !!?

Per577

Do you have any loading data for the 416 and 450 Rigby with VV powder?

I'm currently using MRP for my 416 but I rather use VV if I got some data.

Norma is perhaps good but its too expensive I think.

Per577, you are having altogether too much fun. The fun police are going to come and arrest you...

It seems to me that over on Mingo's .510-.505 Ninja thread, that somebody posted a bunch of case capacities, which I then stashed in an MS Works file for future reference. So it's easy for me to quote:

.460 Weatherby 140gr.
.500 Jeffrey 160gr.
.505 Gibbs 180gr.

The .500 Jeffrey is considered to be a particularly vile cartridge because of the slightly rebated rim and short neck, however these shortcomings are reported to be corrected with no other changes (?) by the .500 AHR. Twenty more grains might get you the velocity upgrade you want...

If you must have the largest of everything, I would yield to the expertise of others with regard to the relative merits of necking up the .408 Chey-Tac or necking down the .505 Gibbs.

I'm sorry Thomas.
I don't have load data with vvn-line of powders.But i have another suggestion.try to get the Quickloadprogram.I think they have lots of data with Vithauri powders(at least cartridge of the world, lists some of them).Their load book is also available(vithauris own loadbook).
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And i'm really not sure about my choice in regard of the "beast" i'm thinking of.Thjere are some factors i cannot push aside.
.460,.475,.500 All based on Wby case:the .460 Wby for the big range of bullets(300 gr.-600gr.)It's commercial.
.475 A&M Mag - because it could be loaded to 2700 fps with a 500 gr. !!(it's a wildcat )There are almost none who have it here in Norway, making me "special".
.500 A2 this is the most powerful cartridge,giving me big(hard) time recoil.It can deliever those famous 8000 ft/lbs+++.It's a wildcat ,,and it's the biggest cartridge my rifle can handle, since mine has the Mark V ,wby action. the stock is laminated.
I think .460 is the choice here since i'll be happy with 7800 ft/lbs,and it's easier cause it's commercial,,and if i get a custombarrrel, i'll be able to exceed 8000 ft/lbs,and that makes me happy,(not my shoulder).therfore i'm considering a F990 pad !
Well, in the future a necked up .408 chey tac would also be something to twist my mind on.Wth case capacity over 180 gr. this thing will send 600 gr. bullets to 2750 fps,,and 570 gr. to 2800+fps !!, that's really something !!

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Even though,,it's really hard to get over the mammoth cartridge .577 T-rex with a case capacity of 225,4 gr( german cases)

Ouch! My shoulder is getting sore reading these posts... You guys are into some real big stuff. Hang in there, and have fun! Guy