LH Gain twist.

[Bigwheels]

Hi all. I'm in the planning process for my next barrel for my 300wm. I've decided that I want to try a LH gain twist. The question is what twist? I'm probably going to run the 220 berger, 225 ELDM, or 230 berger or a tip.
Depending on what mv I can get out of the new barrel I may also try the 250 a tip. This go around im not planning to use solids because if i freebore the barrel for those I wouldn't be able to run the others.
My thoughts now are to go with a 9.5 to 8.5 but maybe I should go faster like 9 to 8?
What are your thoughts?
Thanks.

 

[BCX]

I have no personal experience w gain twist but i did spoke w Bartlein last year. I believe they recommended .75 gain max for cup and core bullets.

 

[NoLegs24]

@hic28 is running a 8.75 - 8 LH Gain Twist in his 300 PRC. Shooting factory ammo (225gr ELD-M).
Hammering to say the least....

 

[Bigwheels]

I was debating whether or not to make the switch to the 300prc. Hesitant because of all the new 300WM brass I have in unopened bags.
Also wondering if you can really over stabilize a bullet if not also pushing it to obscene velocity.

 

[THEIS]

I was debating whether or not to make the switch to the 300prc. Hesitant because of all the new 300WM brass I have in unopened bags.
Also wondering if you can really over stabilize a bullet if not also pushing it to obscene velocity.

Hi,

That would depend on what type of projectile. Jacketed or Monolithic.....you can indeed spin a jacketed projectile too fast and cause it to rip out of its' jacket; monolithics do not suffer that fate.

Sincerely,
Theis

 

[Bigwheels]

Yes. That was basically what I was asking. Everything I've read says that a fast twist at ultra high velocity can cause blowups. But could I get to that point with 200+ grain bullets in a 300WM or even a prc? What is the point of diminishing returns when it comes to twist? Will a 220gr going 2900-2950 in a 8 twist be too much? Assuming the gain twist is 1 or less gain.

 

[Bigwheels]

My current barrel really likes the 225 ELDM @ 2800 fps but is 100 fps slower than my last barrel running the 230 Bergers. That one was a 10" twist. This one is a 9.5" twist. Can I assume that if I end up pushing the 225's at 2900 in a 8 or 8.5" twist I will e Ok? Need to figure this out asap. I want to order my new barrel tomorrow.

 

[b6graham]

lots of guys running 8 twists with the 300PRC and 300NM. both of which push faster than a winmag

 

[Bigwheels]

Thanks. I went with a 9.5-8.75 twist. Not going to get the 250s going fast enough to outperform the 220-230gr bullets anyway so I went just a touch faster than the minimum twist for the 230 a tips.

 

[Lowlight]

Serge sent me this group of his LH GT 300PRC with factory ammo group

here is the other thing, cause LH GT Is super easy to load for, but this is factory ammo according to @hic28

This is a feature of GT Barrels, super forgiving

 

[Bigwheels]

I'm liking it. Hopefully I'll be able to get the same results as my last barrel. 2900 fps & bug hole groups. Now if the 4DOF app would let me click something for a LH twist...

 

[hic28]

Yup. I’m impressed so far and only had time to put 20 rounds through it.

I had shot 10 rounds of 6.5prc, (standard 1:8.5 RH twist) right before swapping barrels to the new 300prc LHGT. Both barrels are same profile and length. Noticed where my reticle ended after breaking the shot and the LHGT went 12 o’clock about .5 mil over POA/POI. The RH twist with a lower recoiling round bounced at about 1:30-2 o’clock same distance.

my 24” 300wm barrel (Factory AXMC) bounces about a mil off to the 1:30-2

if I get around to it, I can film some scope cam to show better what I’m blabbing about

while zeroing, first round low, came up a 10th then next 3 through a hole that looks like 2

 

[_Windrider_]

I’m a believer. I will always use gain twist from now on

 

[1moaoff]

Unfortunately I have 10 or 12 on the shelf so no gain tw for awhile for me