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50-505 Gibbs Match?

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11 October 2004, 20:02
Bwana-be
50-505 Gibbs Match?
Anyone have any idea how this would perform?

Gibbs case necked to .510 and blown out to the hilt for a single-feed CZ,with a Hornady seated comfortably in the neck, COL wherever it falls.

Maybe a silly idea, but it's pretty tough to get into the BMG game without lotsa bucks. Thinking this might make for a decent 1km shooter.

Who knows the length and BC of Hornady's A-Max?

BTW, I'm guessing about 165-168g of water under the bullet.
12 October 2004, 03:42
steve505
Bwana,

ran thru QKL using your capacity estimate:

750g A-max, OAL=5.2", 24" barrel gave
2017fps@39.6kpsi (MAP for gibbs)

the low pressure brass and action keep this below 2000fps.

rgds,

steve
12 October 2004, 04:40
Jiri
But what about .50/.408 Chey_tac, I belive it was mentioned hundred times . . .but no personal experience with something like that

Jiri
12 October 2004, 04:42
Jiri
And there is .50 Peacekeeper, I belive identical to .500 A-square, SSK Industries claim that :

SSK is now making new sporting and tactical rifles from Brown and other new actions such as Sako. A wide variety of actions, stocks and calibers are available. .50 Peacekeeper = 88% of a 50 browning from a 23" barrel plus brake in a 13-14 pound rifle. Recoil is not as bad as most 35 pound 50 BMG rifles. It does 2400 FPS with a 650 and 2200+ with a 750 hornady with excellent accuracy.
12 October 2004, 12:43
Paul H
I don't know that you'd really be saving that all much. 505 gibbs brass is more then 50 bmg brass, and getting the gun built isn't going to be that much less. You're real savings will be powder consumption.

I know folks have used the 500 A-square to launch the 650 gr mil surp pills ~2200 fps.
12 October 2004, 18:21
Bwana-be
Is the CZ rated at only 40k psi? The A-Square must be higher than that.
And how do we know what the Gibbs case can handle? Just because the original specs used that pressure to get the performance they were seeking, doesn't preclude a higher pressure load in that case, does it?
The ChayTac may be the ticket, though I don't know how long it is. Brass is way expensive, I'm sure, but when you can get a CZ rebarreled for maybe $1k, I can't imagine getting into a BMG for less than double that.
BTW, I'm thinking more like 30" bbl.
And even at 2000 fps it would stay super-sonic to about 1k (though it would take almost 2 seconds to get there.) 2200 would put you comfortably supersonic.
Very similar actually to the 185g Berger VLD going 3k fps.
13 October 2004, 08:10
Paul H
Quote:

BB,
the CZ loads, factory, 458 lott.. a 60k+ psi load...

you tell me...


if you want to get into the 50 game, have pacnor throat your rifle an +.500 from a 510wells.

jeffe



True, but the gibbs is over 50% larger in dia, so bolt thrust for a 458 Lott @ 60 kpsi would be the same as the 505 @ 40 kpsi.

With a 30" barrel, I'd think the 500 A-sq would perform fairly well, and brass would be cheaper and easier to get. Whatever route you go, make sure you get brass in hand first. With the more esoteric big bores, brass can take many months to obtain.

If you really want to play the 50 game, I think you might as well go all out with the BMG. In the overall picture, the cost isn't that much, and I'm sure re-sale will be much better than a wildcat that won't appeal to big game hunters, nor long range target shooters.
13 October 2004, 03:17
jeffeosso
BB,
the CZ loads, factory, 458 lott.. a 60k+ psi load...

you tell me...


if you want to get into the 50 game, have pacnor throat your rifle an +.500 from a 510wells.

jeffe
13 October 2004, 02:23
steve505
do not really know about the brass. I think horneber has a thicker web than bertram and probably could be pushed.

I was thinking of bolt thrust on the CZ. In some pass threads, someone published the rated CZ action rating and i think the gibbs at normal pressure was about 1/2 of the max. so some room to spare.

steve