I need some help here. I simply necked up some 404 Jeffery cases to .458. The way I understand it, this is the 460 G&A round. Am I done?

So just order a 460 G&A reamer, dies, gauges, and I have a 460 G&A DG rifle? Or is there some variation to the expanded cases that needs to be performed to make them a "standard" 460 G&A cartridge?

Any experience you would want to share would be appreciated.

Bill,
I believe it is also "improved" off the 404 cases. Which means fireforming.. not a big deal, but it is.

The 404 cases mean the longer actions and/or the associated feeding issues.

It also means $2 brass.

May I humblely suggest the 458 AR?
50¢ brass (headstamped will be available sooner or later) (rum)

standard actions (anything that will hold a 7/300/338/458win)

easy feeding

matches the lott, and then some

cleans up a 458 winmag chamber nicely!

no need to buy the reamer/gages and THEN the barrel

ch4d makes dies

and, after all, it IS named for Accurate Reloading

link to AR diagrams

Bill, I keep pushing someone to build a .458 African Express, also based on the 404 as designed by a new AR member Pierre van der Walt of South Africa. I'm sure you saw some of the posts on that. I keep pushing because I want someone to build one and then tell us all what it's worth. Probably not much different at the muzzle from a .460 G&A or 458 AR, although each designer will probably tell you his is the best.

Will I am looking at the 460 G&A demensions & they are as follows:

OAL 2.800
Base of case to bottom of shoulder 2.248
15 degree shoulder
diameter at shoulder .530

here is a photo from the artical. Its from a old gun rag.

The GA short has a pretty long neck, which leaves some case capacity on the <designing> table, if you will.

jeffe

Thanks for the help.

But if one just leaves the expanded 404 case as it comes out of the epander die, a 404/458 case, how much worse can it be than the 460 G&A case? The case capacity is greater than the Lott and I do not appreciate whether the case really needs a sharper shoulder than as comes out of just the expanded case. In other words I do not know how this shoulder angle affects velocities or pressure. My gut instinct is that the effect cannot be much.

So if one has to pay $250 for dies, $200 for a reamer, and $100 for gauges, does it really matter, cost wise, whether the case is a 460 G&A cartridge or a simple 404/458 case?

Bill,
the shoulder angle, and amount, is a HUGE effect.. venturi effect, or why rockets work, rather than a "flare stack"... more or less, the more shoulder and angle, to a point, the more efficent it will be, in the operating zone... or when the pressure/volume goes up enough ot make the shoulder make a nozzle vs just a constriction. goddard might have written a book or two on that

150 for dies, from CH4d, and find a smith with a reamer.. or rent one

The big issue is reliable headspacing. I'm of the opinion within reason case capacity is case capacity, so a slight increase on capacity by a sharper shoulder is of little concern to me when the case is already large enough.

What is of concern to me is a round that has enough shoulder to reliably headspace on, and a 458-404 IMHO doesn't have enough shoulder for that.

The 450 AR was designed to have a proper shoulder for headspacing, as it was first designed to have enough shoulder to headspace the 470 AR, and necking it down resulted in even more shoulder.

If you're going to pay $2 a case, you might as well go with a 450 Rigby or 460 Weatherby. Even lower pressures and no headspace issues.

even if I concede that the shoulder does have some effect it could hardly be even vaguely related to a venturi!

Admittedly there is not much of a shoulder on the 404/458 and the angle is pretty shallow, but it does have a shoulder. It seems to me that there are at least a few cases that are worse, like the 470 NE.

Will see what RCBS says, or sell all my Jeffery cases. Thanks for the input.

quote:

Originally posted by Will:
even if I concede that the shoulder does have some effect it could hardly be even vaguely related to a venturi!

heh..

take a 308 case...

cut it off 1/3" below the shoulder...

go to a hobby store...

buy a pack of D sized rocket engines....


look at the nozzle/venturi.....while you have the cutoff case (neck/shoulder/part of body)...

and recall that the throat/neck/rifling is NOTHING but an expansion chmaber....



http://en.wikipedia.org/wiki/Venturi

jeffe

quote:

Bill, I keep pushing someone to build a .458 African Express

Wink, I would love to hear from someone who has one...it just seems like the perfect .458 cartridge to me!!! Fits well in a STD Mauser without opening it lengthways (obviously mag needs work), keeps pressures reasonable, gets desired ballistics from a 22" barrel!! I am sure a 'normal' mag box could easily keep 4 down too. Its my dream big bore right now!!

Let me know if you see one! I have emailed Phillip Pfieffer (Africanhuntinginfo) and hope Pierre v.d. Walt can help us.

quote:

Originally posted by Will:
(sic)

Admittedly there is not much of a shoulder on the 404/458 and the angle is pretty shallow, but it does have a shoulder. It seems to me that there are at least a few cases that are worse, like the 470 NE.

Will see what RCBS says, or sell all my Jeffery cases. Thanks for the input.

Yeah, but the 470 NE has a rim to headspace on!

There are plenty of folks who have loaded for rounds with marginal shoulders for headspacing, and to a man they'll admit that it is a PITA.

DGR's should be reliable, which includes a cartridge design that will reliable feed and fire.

Yeah! what Jeffe said.

Rich

Will,
What Paul H said: ditto.

The 10.75x68mm Mauser has less shoulder than the .458/.404 Jeffery (in the step per side) but the shoulder angle is made 28 degrees in the 10.75 and it works.

The .404 Jeffery has minimum case body taper already, so it cannot be improved by blowing out, except in that long sloping shoulder area that is only 8.5 degrees.

That is the weakness of your .458/.404 Jeffery.

The 460 G&A is only 15 degrees. It ought to be 30 degrees, like the .404 Dakota.

quote:

Originally posted by RIP:

The 460 G&A is only 15 degrees. It ought to be 30 degrees, like the .404 Dakota.

36.5deg .. like the AR.. stops like a BRICK