Question on twist for 338 Lapua

[cadborg]

I am having my first full custom rifle built. Caliber is going to be 338 Lapua. I currently have a factory barreled 1/10 twist Remington LSS left hand 338 RUM. It shoots 210-265 grain bullets fine, but I am planning on shooting 250-300 grain bullets with this new build. I prefer mono metal bullets for hunting, such as the Barnes LRX, Cutting Edge Lazer or Badlands Bulldozer type. When I plug these bullets into the Berger stability calculator at 338 Lapua speeds, it looks to me like I should be looking at between a 1/8 or 1/9 twist barrel for "solid" stability through the full range of conditions I hunt in (300 feet to 7000 feet elevation, 10 degrees to 80 degrees F temp depending on the game animal). My only experience is with my 1/10 twist 338 RUM, so I am hoping for some info on what will be the best twist for the types of bullets I described. I also don't want to make a mistake and go with too fast a twist, leaving me possibly stuck with a small selection of bullets the rifle will theoretically shoot well.

In case anyone is wondering - I am moving away from the 338 RUM, mostly due to the availability of brass and reloading data, but also because I might eventually re-chamber the rifle to 338 Lapua improved.

Any help would be appreciated.

 

[Barehandlineman11]

I run 1-9.4 in my lapua ai from sea level too 9,000 with 300 bergers. Youll be around 250gr coppers with that twist. But youll also be single feeding with anything heavier

 

[FEENIX]

I went with 1:8" on my .338 Thor (NMI).

 

[TopPin]

If your going to run sub 280 grain cup and core bullets a 1-10 should be fine, but if your going to shoot a mono bullet, all copper your going to need to run a minimum of 1-9.3 above 260 grains. Heavy for caliber copper bullets will require more twist to stabilize past 800 yards. Trust me, I've tested it, a lot. If you're going to build a rifle I'd recommend at minimum to run a 1-9.3 twist or faster. It will not be detrimental to cup and core bullets, and will give you a broad spectrum of mono bullets to shoot as well. I look at barrel twist like spinning a top on a table especially with all copper bullets, the faster you can spin it the longer it takes for it to start to wobble. After that begins everything starts to unravel. Most common factory options are 1-9.3 and above in 338, now if you wanted to customize a barrel for heavy for caliber 338 offerings in a monolithic bullet (all copper) I'd order a 1-8 or 1-8.5 to stabilize the heavy coppers. Cup and core offers a lot more breathing room in barrel twist, as to responding better to slower twist rates at heavy for weight.

 

[cadborg]

If your going to run sub 280 grain cup and core bullets a 1-10 should be fine, but if your going to shoot a mono bullet, all copper your going to need to run a minimum of 1-9.3 above 260 grains. Heavy for caliber copper bullets will require more twist to stabilize past 800 yards. Trust me, I've tested it, a lot. If you're going to build a rifle I'd recommend at minimum to run a 1-9.3 twist or faster. It will not be detrimental to cup and core bullets, and will give you a broad spectrum of mono bullets to shoot as well. I look at barrel twist like spinning a top on a table especially with all copper bullets, the faster you can spin it the longer it takes for it to start to wobble. After that begins everything starts to unravel. Most common factory options are 1-9.3 and above in 338, now if you wanted to customize a barrel for heavy for caliber 338 offerings in a monolithic bullet (all copper) I'd order a 1-8 or 1-8.5 to stabilize the heavy coppers. Cup and core offers a lot more breathing room in barrel twist, as to responding better to slower twist rates at heavy for weight.

Thank you, this helps. So, if I am understanding correctly, a lead core 265 or 300 grain like the Nosler Accubond LR should still theoretically shoot OK in a 1/8 or 1/8.5 twist barrel, but those twist rates should be spot on for the heavy copper types, like the 250 or 275 grain Badlands Bulldozer's? I will primarily be using heavy copper types or hunting, but I live in Oregon and get to frequent the little shop next door to the Nosler factory, so I have been able to pick up the factory second Nosler ABLR's and regular Accubonds for practice, etc.

 

[cadborg]

I went with 1:8" on my .338 Thor (NMI).

Thanks for the info. If you don't mind sharing, what brand of barrel did you go with and any regrets on the 1/8 twist? Assuming I plugged in the data correctly on the Berger stability calculator, it looked like the 1/8 twist was going to work well for the bullets I want to shoot, but I have no in field experience with that twist rate.

 

[WeiserBucks]

Whatever bullet you want to shoot, the manufacturer will list the minimum required twist rate.

 

[338 dude]

I am having my first full custom rifle built. Caliber is going to be 338 Lapua. I currently have a factory barreled 1/10 twist Remington LSS left hand 338 RUM. It shoots 210-265 grain bullets fine, but I am planning on shooting 250-300 grain bullets with this new build. I prefer mono metal bullets for hunting, such as the Barnes LRX, Cutting Edge Lazer or Badlands Bulldozer type. When I plug these bullets into the Berger stability calculator at 338 Lapua speeds, it looks to me like I should be looking at between a 1/8 or 1/9 twist barrel for "solid" stability through the full range of conditions I hunt in (300 feet to 7000 feet elevation, 10 degrees to 80 degrees F temp depending on the game animal). My only experience is with my 1/10 twist 338 RUM, so I am hoping for some info on what will be the best twist for the types of bullets I described. I also don't want to make a mistake and go with too fast a twist, leaving me possibly stuck with a small selection of bullets the rifle will theoretically shoot well.

In case anyone is wondering - I am moving away from the 338 RUM, mostly due to the availability of brass and reloading data, but also because I might eventually re-chamber the rifle to 338 Lapua improved.

Any help would be appreciated.

I'm running a 28 inch bartlein 9.3 twist on mine.

 

[FEENIX]

Thanks for the info. If you don't mind sharing, what brand of barrel did you go with and any regrets on the 1/8 twist? Assuming I plugged in the data correctly on the Berger stability calculator, it looked like the 1/8 twist was going to work well for the bullets I want to shoot, but I have no in field experience with that twist rate.

CarbonSix .860" at the muzzle; no regrets. Yes, it will work for your intended purpose.

 

[TopPin]

Thank you, this helps. So, if I am understanding correctly, a lead core 265 or 300 grain like the Nosler Accubond LR should still theoretically shoot OK in a 1/8 or 1/8.5 twist barrel, but those twist rates should be spot on for the heavy copper types, like the 250 or 275 grain Badlands Bulldozer's? I will primarily be using heavy copper types or hunting, but I live in Oregon and get to frequent the little shop next door to the Nosler factory, so I have been able to pick up the factory second Nosler ABLR's and regular Accubonds for practice, etc.

Yes the Accubond will stabilize just fine, along with many other cup core bullets in a faster twist. As far as cup and cores are concerned running a faster twist may or may not decrease velocity in the same length barrel. In comparison testing typically mono bullets in comparison to cup and core bullets of the same weight class produce higher velocity. If your shooting a mono bullet typically you will see an increase in speed due to cooper being lighter, decrease in bearing surface, and decrease in bullet constriction traveling down the barrel (hypothetical as there is no proven hard evidence as the bullet moves down the barrel) but an all copper bullet does not deflect as much as lead core copper jacketed bullet while moving down a barrel due to not having duel materials reacting to pressures being created. This is my hypothesis. Depending on bullet manufacture typical speed increase of 25-100+ fps copper vs lead core bullets in the same weight class.

 

[C.O. Shooter]

30" 1-9 5R Heavy Palma

Currently hunting/shooting the 275 Badlands SBD2s, no issues.

 

[skipglo]

30" 1-9.25 here 5R as well. Shóoting 300 A-tips, 300 Nosler, 300 SMKs...

 

[sierracharlie338]

1-9.4 on mine

 

[cadborg]

Thanks all for the replies, I appreciate it.