1 in 12 in 308

[avfromvt]

Just getting my first long range rig I really want to start with a factory rifle. I settled on the CZ 550 varmint in 308. The barrel twist rate is 1 in 12, the standard seems to be more like 1 in 10. I will be shooting factory ammo probably 168 or 178. Is there any disadvantages to the faster twist rate. This will be a deer rifle for out to 500-600 yards.

 

[blipelt]

A slower twist like the 1:12 might not stabilize a heavier bullet. Don't have much experience with the 308 yet just picked one up yesterday. Cooper classic weighs only 7.5lbs with 4.5-14 CDS on top. Mine has the 1:10 and from the group and load from the factory they shot was one hole group with 168smk. I would try and find a 1:10 if it was me.

Brent

 

[hatfield954]

I can't think of a disadvantage of having a faster twist rate right at this moment. I found out a faster twist rate requires a heavier grain bullet to stabilize better for accuracy. A 1 in 12 twist rate is slow and should stabilize better with a lighter grain bullet, like 150's. You can find factory ammo even lighter than that if you just had to. I don't know what the terminal ballistics would be like at that range with a bullet lighter than a 150. I had a remington .270 and had to use the heaviest grain bullet i could find to get it to shoot good groups. It had a fast twist of 1 in 8. Barrel length may be one factor to your question.

 

[liltank]

I have been shooting a .308 for 4yrs. It has been my conclusion that 1:12 is all a perspective user of the.308 needs. I initially had a 1:10 twist. This caused higher pressures in heavier bullet loads. I have found no evidence that a 1:12 twist barrel is any less accurate than a 1:10. For the weight bullets a .308 can fire efficiently, the 1:12 will handle anything you can put in it. I have had success with bullet weights up to 210gr. However, my current accuracy of .25 to .4 MOA is with 175 Nosler Custom Comp hand loads out to and beyond 810yds. I have also had success with Hornady 178's with .25 and .5 MOA groups. This is of course with an aftermarket barrel (1:12), but most factory barrels will do just as well with proper break in and ammo. The CZ is a very capable rifle. I have full confidence that it will fulfill all your needs. Just a little FYI, the 1:13 twist used by Palma shooters will stabilize up to a 180grn bullet. Have fun and hope you enjoy your new toy.

Tank

 

[blipelt]

Tank have you ever tried to see if the faster 1:10 will stabilize a little better when the projectile goes subsonic? Get a little more distance out of her. Just something someone visited with me once.

Brent

 

[WildRose]

This rifle is built specifically as a varminter, that's why it has the slower twist rate than a tactcal or "hunting model".

Stick with the 150's or lighters bullets and it should work very well for you.

 

[Guy M]

The 1:12 twist normally handles up to 180, even 190 gr SMK's well. At least that's been the case in my rifle.

I prefer to shoot the 155 - 175's from the .308 Win, but the rifle certainly handles the heavier bullets fine, even out at 600 yards.

Regards, Guy

 

[Greyfox]

I've had 308's with 1:10, mil-spec 1:11.25, and 1:12. Used them all with 168 and 175 SMK's. Haven't seen a difference in accuracy with these weights. I'm partial to the Mil-Specs with 168's. Seems to clean up faster, and I have shot as much as 200 rounds before cleaning and still hold zero, and accuracy , hot or cold. Accuracy good to about 2500 rounds. Would probably get more, but shoot hot frequently. Typical performance is between .25 and .5 MOA /5 shots.

 

[liltank]

Tank have you ever tried to see if the faster 1:10 will stabilize a little better when the projectile goes subsonic? Get a little more distance out of her. Just something someone visited with me once.

Brent

I've got to be honest I have not shot it far enough to give hard data. I have shot to almost 1100yds and impacts are consistent to that distance.

Tank

 

[Willfully Armed]

Late to the party but maybe it will help another in the future. Ive had a 550 varmint 308 for about a decade now.

It sits in the 750 "sniper" stock. Harris BRM pod, Bushnell elite tac 6-24×50 in CZ rings, and SiCo Specwar7.62 on the end. Shooting it sounds like a wheezing cough with the can on. The bullet impact on a deer at 240 yards is audible over the muzzle blast, whump.

My first load results were 168 SMK over 44.2 RL15 at 2.815". 0.015 jump. 0.38" groups at 100. I then developed a sierra 2130 150gr Spitzer load over win748 that chronoed at a meager 2600 fps, but also held 1/4-1/3MOA out to 300 yards. 4 years ago I hot a few boxes of 168 factory speer Gold Dots, and was immediately amazed. A factory load that ran a 3/4" group at 300 yards and has exhibited perfect terminal capabilities on deer.

It runs 155gr sierra Palmas as well as it does 168 smk. It wouldn't run sub MOA with 175smk. For grins someday I will see what the 178 hornady and 175 VLDs will print.

RL15, win748, xbr8208, h335, h4350 have all shown good groups with previously mentioned projectiles. 8208 is easily my favorite.

Suppressor changes POI approx 2", but it never gets shot without it. Suppressor did not negatively impact groups.

It weighs 16.8# with the bipod, suppressor, and loaded 10rd mag. I hunt from a prone position, so it only sucks to carry to and from the truck. Off hand shots aren't really a thing.

 

[javman]

I've got the same one as you but it sits in a Boyd's Taticool stock and it is a .30 shooter with the 168Amax and NoslerBTHP 168s. It will out shoot my buddies custom action 308 all day long. 168Amax have never let me down on deer.

 

[shooter7]

I got my start into long range shooting with a 1-12 twist 308 win. It absolutely loved 168 Sierra Match Kings and the 168 Hornady AMax. I got useable accuracy with 175 and 180s but it definitely shot best with 168's.

 

[Coldfinger]

Just getting my first long range rig I really want to start with a factory rifle. I settled on the CZ 550 varmint in 308. The barrel twist rate is 1 in 12, the standard seems to be more like 1 in 10. I will be shooting factory ammo probably 168 or 178. Is there any disadvantages to the faster twist rate. This will be a deer rifle for out to 500-600 yards.

For the average .308 seems a 1/12 would be fine.

 

[ButterBean]

I have a Rem 11.25 twist, 178 ELDX with Varget , or RL15 all shoot the same same, RL 15 is the fastest and 8208 is the slowest