Welcome, Guest
Username Password: Remember me

Reloading the 458 win mag
(1 viewing) (1) Guest
  • Page:
  • 1

TOPIC: Reloading the 458 win mag

Reloading the 458 win mag 5 years, 11 months ago #544

  • Frederik
  • OFFLINE
  • Gold Boarder
  • Posts: 254
  • Karma: 4
Myself and Charl just bought ourselves a Sako 458 win mag for the company. So now the long process and wait is starting.

But in the meantime we can always gather reloading info for the 458. I'm thinking of going the 450gr route and skipping the heavier 500gr bullet all together. Any load data with certain bullets will be appreciatted as well as on hand experience.

Also does anybody know where to get good affordable brass as well ? And which dies would be the best suited ?
Frederik Cocquyt

Sleeping under the African Sky I cannot see anything wrong with the world !

Re: Reloading the 458 win mag 5 years, 11 months ago #546

Hi Frederik

Sako's in the heavier calibres are known to suffer split stocks behind the tang. My 375 H&H has done it and I've seen a lot of posts on AR in that regard. I'd suggest while your'e waiting for it have the bedding checked/done and considder an extra cross bolt.
I hunt because I'm human; hunting is the expression of my humanity.
Life's too short to hunt with c***s

Fast is fine, but accuracy is everything.
Xenophon-c. 430 – 354 BC

Re: Reloading the 458 win mag 5 years, 11 months ago #547

  • Frederik
  • OFFLINE
  • Gold Boarder
  • Posts: 254
  • Karma: 4
No problem there its a synthetic stock, the rifle was used by an ex PH from Zim
Frederik Cocquyt

Sleeping under the African Sky I cannot see anything wrong with the world !

Re: Reloading the 458 win mag 5 years, 11 months ago #550

Big Bore Journal No. 9 contains an excellent article on page 10 by Fred van der Westhuizen with the title “Open Your Eyes: The .458 Win Mag is the real deal”. The .458 Win Mag got a bad reputation because it failed to deliver the claimed muzzle velocity of 2130 - 2150 ft/s with 500gr bullets. The British .450 cartridges achieved the +/- 2150 ft/s muzzle velocity (apparently with 28 inch proof barrels at the factory while the rifles used by hunters probably had shorter barrels) and got good reputations in Africa. Fred’s article shows that it does not make sense to sing the praises of the British .450 cartridges, including the .470 NE, while bad-mouthing the .458 Win Mag since these calibers all fall in the same +/- 2150 ft/s muzzle velocity range with 500gr bullets.. However, the question remains: how do you achieve +/- 2150 ft/s with Somchem propellants?

Fred’s answer to this question comes from a little soft-cover book titled “The South African Hand Loader”, Reloading Association of South Africa, 2002. On page 103, Org Hamman recommends a duplex load of S335 and S265, with 85 % of the load S335 and 15 % S265, for 500gr bullets. Start load is given as 68gr and maximum as 70gr. Org claims to have achieved 2160 ft/s muzzle velocity, without signs of excessive chamber pressure. I decided to follow Org’s advise, to see what muzzle velocity I can achieve with my 1970 Brno ZKK 602.

I used new Winchester cases, CCI 250 primers and 500gr Hornady soft point bullets. I ran the new Winchester cases through my RCBS sizing die and trimmed the cases to 63.3 mm.

I calculated the duplex load as follows:
68gr: 57.8gr S335, 10.2gr S265
69gr: 58.7gr S335, 10.3gr S265
70gr. 59.5gr S335, 10.5gr S265

The intention of the faster burning S265 is to provide the required boost to up the muzzle velocity from 1999 ft/s (70gr S335, Somchem Ballistic Data Manual, November 2004 with 500gr Hornady FMJ) to hopefully +/- 2150 ft/s.

I weighed the propellant with my RCBS Chargemaster electronic dispenser/scale combo. The S335 was dropped first in the case, with the S265 dropped on top of the S335. I seated the 500gr Hornady bullets to the cannelure (COL: 85.1 mm), and crimped the cases with the Lee Factory Crimp die. Loaded as such, the duplex load is compressed and mixing of the two propellants is probably limited. On 1 September 2008, I set out to the range, armed with my Chrony.

I set the target at 25 meters, rested the rifle on shooting sticks and from a sitting position, took a full bead with a six o’clock hold:

I decided to up the bead slightly, and I set the Chrony. Note the muzzle velocity on the targets:

68gr


69gr


70gr


Needless to say, I am satisfied with the groups and the muzzle velocity of 2130 ft/s from the 70gr load. While visual inspection is not a reliable indication of chamber pressure, I can report that the fired primers were still rounded at the edge and the bolt not sticky on opening after the shot. In this instance, crimping with the Lee Factory Crimp die does not affect accuracy negatively from a hunting perspective,
as opposed to a bench rest shooting competition perspective. Anyway, the crimped cartridge is robust and need not be carried in a protective box while hunting.

The only remaining problem with the ammo loaded as above, is compaction of the compressed propellant over time. I am going to load some ammo, store it for let’s say 2 years, and then test it on the range. I will also pull bullets to visually inspect the propellant. The obvious solution for now is to shoot only freshly loaded ammo.

The afternoon of 1 September 2008 was windy and chilly as usual. The Chrony was +/- 7 meters in front of the muzzle. By placing the Chrony closer to the muzzle and on a warmer day, slightly higher muzzle velocities may be obtained. Should I worry to reach exactly 2150 ft/s? I think not. Should I go the Lott, 3 inch etc. route? The rifle shoots fine and the 5 cartridges in the magazine feeds flawlessly. It is only when I notice the available length in the magazine of the long 602 action and with the compressed load problem in the back of my mind that I wonder …

Re: Reloading the 458 win mag 5 years, 11 months ago #551

  • Frederik
  • OFFLINE
  • Gold Boarder
  • Posts: 254
  • Karma: 4
Thanx Johnannes very informative, have you done any testing with 450gr bullets ? I want to try and concentrate to use those instead of the 500's.
Frederik Cocquyt

Sleeping under the African Sky I cannot see anything wrong with the world !

Re: Reloading the 458 win mag 4 years, 7 months ago #1177

Hallo Johannes
Het jy weer nuwe nuus oor die mengsel? Het jy enige van die ou ammo getoets om te sien wat gebeur?
  • Page:
  • 1
Time to create page: 0.30 seconds