Thread: How to get fast twist barrels in NZ

Ive done a lot of work with sub loads in these cartridges over the years and I cant see any advantage of going to such fast twist barrels for them.. in fact I think you will find they will actually add more issues than advantages such as higher case pressures and wobbly over stabilised bullets.
Hornady is just trying to baffle us with the marketing BS one again.

A history lesson for you may better explain. Back when the late J D Jones thunk up the Whisper idea his intentions were to use the heaviest bullets with the highest BC's in a cartridge just big enough to shoot in the subsonic realm in a fast twist barrel that could stabilise such a bullet at low speeds.
For reference I will only speak of the .300 Whisper and the .338 whisper as this is what you have shown interest in.
JD used Shilen to make custom barrels for him for this venture and his twist rate was 1-8" for both the .300 and the .338 cartridges.
At the time the heaviest bullets available for these two were the Wildcat bullets which were 250gr in .308 and 350gr in .338 which were perfectly stable to 1000 yards with a 1050fps muzzle velocity in these 1-8" twist custom barrels.





Later due to more commercial availability they advised and used the Sierra match king 240gr in .308 and 300gr in .338, both of which were also perfectly stable at sub velocities out to 1000 yards. Why? because that's the twist rate JD settled on after a LOT of testing with custom Shilen barrels.

Fast forward to modern day... enter military contracts and the need for the .300 whisper to be Saami spec, out it rolls with a brand new name... .300 Blackout. This also brought popularity and more availability to components for both rifles and ammunition. While JD discovered that the 1-8" twist was by far the most accurate twist for the .300 Whisper with the 240 and 250gr .308 bullets, the trend was for the shorter AR15s to go to a 1-7" twist and a lighter 180gr to 220gr bullet at sub speeds. You guessed it... The shot like crap compared to the heavies through the 1-8" Shilens... but the single ragged hole subsonic groups had long been forgotten with the requirement for military units to only perform to MOA at 100y.

The crazy thing in all this marketing hype is actually the fact that now we have all these lighter weight special expanding subsonic well balanced bullets the twist rates should actually be getting slower not faster.
Take the new Hornady 190gr SubX bullet for example, it is stable at sub velocities out of a 1-10" twist.

The .338 350gr Wildcat bullet was stable in the 1-8" Shilen barrel but not in the Trueflight 1-9 barrel. The 1-9" truflight only just stabilises the 300gr SMK and not the 300gr Berger VLD at sub speeds so a 1-8" is the best for the .338 for the longest bullets in its class. once again the new expanding sub bullets in .338 are lighter and shorter so a 1-9" or even 1-10" will work fine.
Here is the Berger VLD (Left) and SMK (right) side by side, not a big difference which suggests the 1-9" is borderline to slow for these 300gr heavies at sub speeds:



While it seems Hornady is doing ground breaking stuff... they are just to re-invent the wheel, it has all been done before only on a lesser marketing budget.
8.6 Creedmoor is nothing more than the .338 Whisper which is a 6BR or 7BR cartridge necked up to .338.
once Remington stopped making 7BR brass I started to make my own using stronger Lapua SRP .308 Palma brass in the same fashion you can make .300 whisper/BLK brass from .223Rem brass.





Here are a couple of links to threads Ive started previously dedicated to this topic if you are interested:

https://www.nzhuntingandshooting.co....-300blk-44679/

https://www.nzhuntingandshooting.co....-300blk-44692/