Another Ultra Long-Range caliber

[gvnwst]

Hey guys, had an idea. I was thinking about ULR shooting, and i decided to design a new cartridge. Wadda ya think:

Caliber: .458
Bullet weight: 550gr-600gr
Muzzle Velocity: 3,250-3,500fps
Ballistics are better than the .408 Cheytac, .50 BMG, and .416 Barrett.

I originally decided to base it off the 14.5x114, but then i learned about recoil impulse. So i am thinking a 20mm Hispano or a completely new case, somewhere between the BMG and the 14.5. Any ideas?

I know that this doesn't fill any niche, or fix any problem, i do this for fun. I can get .458 match bullets meant for the .458 Steyr, so that isn't a problem. Tell me what you think!

Thanks,


gvn

P.S. does anyone have a link to the hispano's case dimensions?

 

[Nolo]

Recoil impulse is very important when you are talking about big calibers like these being shoulder fired.
But I am not sure the differences in impulse between, say a 20mm HS and a 14.5x114mm.
Maybe it's similar... maybe it's way different.
You're going to need a very effective muzzle break at any rate. Maybe a hydraulic recoil-reducer?

 

[gvnwst]

I have contacted flint 'n firzzen gun shop about a mcaurther(i think that is what it is called) muzzle brake. they are very effective

Maybe a hydraulic recoil-reducer?

yeah, i was thinking about that, but where can i find those, or even drawings?

 

[Nolo]

As far as I know a hydraulic recoil reducer is just a normal hydraulic actuator, I believe.

 

[dirtyjim]

in finland a few of the long range shooters are making 50 cal willdcats off 20mm brass shortened & necked down for the 50bmg bullets, looks like a 50 PPC. should be able to do something similar in 458. lehigh makes match 458 bullets

 

[gvnwst]

in finland a few of the long range shooters are making 50 cal willdcats off 20mm brass shortened & necked down for the 50bmg bullets, looks like a 50 PPC. should be able to do something similar in 458.

exactly.

 

[gvnwst]

I would probably make a 50 cal version, as well as a shorter .416 and maybe even .375.

 

[Nolo]

You should totally make a .17-20mm...
XD
I am terrible. It would be the .17 Eargenblastenmuchloudenerboomer.

 

[VARifleman]

Why not just make it from 20mm Vulcan? It's short and not too crazy...well, kinda crazy.

 

[gvnwst]

Why not just make it from 20mm Vulcan? It's short and not too crazy

Thought about it, i can't find any more info on the vulcan than the hispano, and the base size is HUGE. massive action needed. this is supposed to fit in a .50 size rifle or something like that

 

[gvnwst]

You should totally make a .17-20mm...

does anyone hear barrels exploding in TX???

 

[VARifleman]

The base size of a 20mm vulcan (20x102) seems to be the same as 14.5x114, which is 27mm.

Sources:
http://www.specialistauctions.com/auctiondetails.php?id=1053696
http://en.wikipedia.org/wiki/14.5x114mm





There is the 12.7x108 Russian you could work off of, but that's hard to find too.

 

[Bendutro]

Cool.

The cost and complexity required to motivate a bullet accurately at those ranges is impressive but it seems that the next step beyond .408 range would be an electromagnetically propelled projectile. 10,000 meters per second takes a little edge off windage effects.

 

[VARifleman]

http://en.wikipedia.org/wiki/12.7x108mm

60 gr water more case capacity than .50 bmg, more of an improved style shoulder, should go well.

 

[VARifleman]

http://www.quarry.nildram.co.uk/an_introduction_to_collecting_20.htm

Down at the bottom is a list, I was wrong on the rim size for the vulcan, it's 29.5mm.

Hispano rim size is 24.5mm.

 

[dirtyjim]

pull out your cartridges of the world & look up the 50 mcmillan fat mac.
mcmillan already built a bolt action rifle base on the 20mm vulcan case shortened & necked down to 50 cal.

 

[gvnwst]

yeah, i know about that. i think a longer necked, .458 cal version...


VARrifleman: i am shortning the case to a more acceptable length, so the 1mm gained by going with the 12.7x108 is not enough to just go with the BMG. the hipano looks about ideal... Thanks.

Cool.

The cost and complexity required to motivate a bullet accurately at those ranges is impressive but it seems that the next step beyond .408 range would be an electromagnetically propelled projectile. 10,000 meters per second takes a little edge off windage effects.

Don't worry, i am working on it....



Does anyone out there have quickload and can run these numbers?

Rim dia: .930"
Case head dia: .932"
Shoulder Dia: .882"
40 degree shoulder
.482" neck OD
.458" bullet dia
.5" neck length
3.5" case length
600gr bullet.

Can you run this with a target velocity of 3,500 fps?

Thanks

 

[VARifleman]

12.7x108 is 9 mm longer than .50 bmg which is 12.7x99, and 12.7x108 is quite a bit fatter at the front than the BMG. It looks like the shape of .300 Win Mag versus .30-06.

 

[gvnwst]

12.7x108 is 9 mm longer than .50 bmg which is 12.7x99, and 12.7x108 is quite a bit fatter at the front than the BMG. It looks like the shape of .300 Win Mag versus .30-06.

Yes, but i want the COAL to be within a BMG length action even though it will be too fat. I would blow out the shoulder and case wall with whatever cartridge i started with. the case wall taper will be about 1/16th of an inch. see above numbers for teh basic outline that i am using. Thanks for the input

 

[gvnwst]

the '108 has just below my target case capacity though.

 

[gvnwst]

Hey, Nolo. Got a cool name for this cartridge? What if i said please?