Barrel twists on your fav .338 long range gun

Black Diamond 408

Well-Known Member
Sep 6, 2003
Im currently working on a project by necking the 505 down to .338 cal. I'm wondering what twists your longrange guns have, bbl length and the speeds you run with the Sierra 300gr bullets. I want to compute the twist i will need for this bullet, the new case should be capable of launching the bullet at speeds over 3500fps. I need to have a twist that will not over spin the bullet so it will stabilize out at 1000yds or farther. I have a pic of the formed case if any one wants to see it i can email it to you. It most likely will have a 35deg shoulder.

DC did a workup on the wildcat and it looks very promising!!

Darryl Cassel

Well-Known Member
May 7, 2001
My two 338/416 IMP has a 10 twist.

The 37" barrel on the one has produced 3310 FPS using the 300 Gr Sierra MK.

The case has a 35 degree shoulder.


chris matthews

Well-Known Member
May 14, 2001
Urich, MO
I don't feel you can "over spin" a bullet as I have shot several fast twist guns with light bullets and had no problem. However I tend to go with the slowest twist I can get away with. For example- 1 in 11 for 300 Win Mags up to 210 gr bullets. Boots Obermeyer uses a 13 for 190.
You can literally spin the jacket off in too fast on light made bullets.
To answer your question a 10 will work great or maybe a little slower. Remember, the faster you push the bullet, you can get away with a slower twist.


Well-Known Member
Dec 11, 2002
According to almost everyone here,the twist for .338 300 MK:s is 10". Man,I was more than happy to find out that my TRG-S has a 10" twist (instead of the still advertised 12"), otherwise I´d stayed with 250 grainers.

Very low ES,some bedding things to fix now but my first shot is always where it´s supposed to be with the MK:s and the deer are out there now...

The Greenhill Formula gives you 9.95" for that combo too.

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