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1 in 14 twist 458
- Thread starter epanzella
- Start date
In my 458 SOCOM (AR15 platform, 16"), 1 in 14 twist, the Lee 460-350 bullet cast from wheel weights (lead, tin, antimony, arsenic), water quenched from the mold (hardens it up to maybe 16-20 brinell), with gas check, seems to have a nice SD at 1550 fps with 26.0 grains surplus WC820 powder. But this is just a mild, comfortable plinker with enough powder to reliably cycle the action, then increased incrementally to tweak the SD small, and I haven't tried to drive them faster.
Data for the Lee 460-350 cast load (10 shots):
WEIGHT: 366
AVG FPS: 1545
ST DEV: 15.98
ES: 43
FT LBS: 1941
For more serious work I use the Remington 300 JHP at about 1875 fps, Hornady 350 JSP at about 1750 fps, or the Remington 405 JSP at 1575. And the 1 in 14 is a fast enough twist to stabilize 500 grain cast bullets at subsonic velocity, ~1050 fps, for suppressed use, as well (great for hog hunting with night vision, when hoping for multiple engagements per night).
This, below, from the .458 SOCOM article in Wikipedia, may be closer to what you originally asked about and what can be expected to work well from a 1 in 14 twist 458 barrel:
----------------------------------
Ballistic performance
Bullet weight/type Velocity Energy
250 gr (16 g) SP 655 m/s (2,150 ft/s) 3,478 J (2,565 ft•lbf)
300 gr (19 g) HP 580 m/s (1,900 ft/s) 3,261 J (2,405 ft•lbf)
325 gr (21 g) FTX 566 m/s (1,860 ft/s) 3,384 J (2,496 ft•lbf)
405 gr (26 g) JFP 489 m/s (1,600 ft/s) 3,148 J (2,322 ft•lbf)
600 gr (39 g) RN 304.8 m/s (1,000 ft/s) 1,811 J (1,336 ft•lbf)
--------------------------------------
The .458 SOCOM cartridge was developed specifically for use in an AR15 platform and so the pressure spec is limited by the AR15 bolt and lockup strength, and stronger guns made to shoot the .458 at higher velocities use slower twists for reasons previously mentioned.
Also, the water quenching of lead alloy cast projos, dropping them directly from the mold into water, hardens them up and allows good results up to maybe 2200 fps, if all other factors are ideal.
I'm no expert, but the 1 in 14 may have been a bit too fast for your stated goal, and it sounds as if you should have no problems pushing 300 to 400 grain hardened, cast, gas checked bullets at 2000 fps from your 1 in 18 .458. Might be ideal, especially with a really good recoil pad...
Data for the Lee 460-350 cast load (10 shots):
WEIGHT: 366
AVG FPS: 1545
ST DEV: 15.98
ES: 43
FT LBS: 1941
For more serious work I use the Remington 300 JHP at about 1875 fps, Hornady 350 JSP at about 1750 fps, or the Remington 405 JSP at 1575. And the 1 in 14 is a fast enough twist to stabilize 500 grain cast bullets at subsonic velocity, ~1050 fps, for suppressed use, as well (great for hog hunting with night vision, when hoping for multiple engagements per night).
This, below, from the .458 SOCOM article in Wikipedia, may be closer to what you originally asked about and what can be expected to work well from a 1 in 14 twist 458 barrel:
----------------------------------
Ballistic performance
Bullet weight/type Velocity Energy
250 gr (16 g) SP 655 m/s (2,150 ft/s) 3,478 J (2,565 ft•lbf)
300 gr (19 g) HP 580 m/s (1,900 ft/s) 3,261 J (2,405 ft•lbf)
325 gr (21 g) FTX 566 m/s (1,860 ft/s) 3,384 J (2,496 ft•lbf)
405 gr (26 g) JFP 489 m/s (1,600 ft/s) 3,148 J (2,322 ft•lbf)
600 gr (39 g) RN 304.8 m/s (1,000 ft/s) 1,811 J (1,336 ft•lbf)
--------------------------------------
The .458 SOCOM cartridge was developed specifically for use in an AR15 platform and so the pressure spec is limited by the AR15 bolt and lockup strength, and stronger guns made to shoot the .458 at higher velocities use slower twists for reasons previously mentioned.
Also, the water quenching of lead alloy cast projos, dropping them directly from the mold into water, hardens them up and allows good results up to maybe 2200 fps, if all other factors are ideal.
I'm no expert, but the 1 in 14 may have been a bit too fast for your stated goal, and it sounds as if you should have no problems pushing 300 to 400 grain hardened, cast, gas checked bullets at 2000 fps from your 1 in 18 .458. Might be ideal, especially with a really good recoil pad...
- Joined
- Apr 8, 2013
- Messages
- 2,040
Thanks for the good info. Once I found the cheap 1 in 14 barrel was no longer available and I would have to have it built, I decided to fall back to my original choice of 1 in 18.
