Optimal twist rate .308
- Thread starter JLK
- Start date
bamaranger
New member
duly noted
All the above is duly noted. Why does Savage ( and others) twist their .308 rifles in 1-10? I have an older Winchester 88 twisted 1-12.
All the above is duly noted. Why does Savage ( and others) twist their .308 rifles in 1-10? I have an older Winchester 88 twisted 1-12.
bamaranger
New member
thinking
I should think before I post.
Sorry
I'd expect 1-10" is a good compromise twist rate for GP applications like a sporter.
I should think before I post.
SorryI'd expect 1-10" is a good compromise twist rate for GP applications like a sporter.
Ask them.
A common premise is the 30-06 normal twist is 1:10 and the 308 slightly less muzzle velocity needs the same rate of twist. Remington and others twisted some 308 target barrels 1:10.
Savage model 12 Palma rifle's 30" barrel has a 1:13 twist. Perfect for best accuracy with 150 to 155 grain bullets leaving 3000 fps heading for targets 800 to 1000 yards down range. 7.62 NATO M80 ball ammo with 145 grain bullets in like barrels oft times shot most accurate from 1:14 twist barrels at those ranges.
It's all about the bullets rpm rate calculated with this formula:
muzzle velocity in fps X 720 / twist in inches = rpm
What is a GP application?
Last edited:
Jim Watson
New member
General Purpose.
I think they use a 10 twist in .308 so they can use the same barrel blank in all .30 cal. except the specialty Palma rifle Bart mentions.
I think they use a 10 twist in .308 so they can use the same barrel blank in all .30 cal. except the specialty Palma rifle Bart mentions.
This has been discussed on every firearms forum on the Planet. 8,990,000 results from a net search for 'M-14 match rifle rifling twist'.
"...Why does Savage..." Cost. A .30 calibre hunting rifle is a .30 calibre hunting rifle to them. Costs more to make a barrel with a different twist for every .30 cal. cartridge.
The standard M-14 rifling has right-hand twist in 1:12 inches with 4 grooves for 147 grain 7.62NATO. (There was no .308 prior to the M-14.) An M1A National Match has a 1 in 11 twist. Unreliable sources(a web site) says National Match M-14's had 1 in 10 with M118 Match ammo(173gr FMJBT).
I really think the last thing you need to concern yourself about when building/buying a .308/7.62 rifle is the rifling twist. The trigger, bedding and sight are more important. With what you're doing with it being most important.
"...Why does Savage..." Cost. A .30 calibre hunting rifle is a .30 calibre hunting rifle to them. Costs more to make a barrel with a different twist for every .30 cal. cartridge.
The standard M-14 rifling has right-hand twist in 1:12 inches with 4 grooves for 147 grain 7.62NATO. (There was no .308 prior to the M-14.) An M1A National Match has a 1 in 11 twist. Unreliable sources(a web site) says National Match M-14's had 1 in 10 with M118 Match ammo(173gr FMJBT).
I really think the last thing you need to concern yourself about when building/buying a .308/7.62 rifle is the rifling twist. The trigger, bedding and sight are more important. With what you're doing with it being most important.
The 1:10" twist in 30 caliber was adopted decades ago by the industry as appropriate for everything up to 220 grain bullets. Most people don't shoot 220 gr bullets, but for mass production you want "one size fits all". Different special application rifles will have different twist rates.
The 308 Winchester was introduced 2 years before Frankfort Arsenal finalized the 7.62 NATO cartridge. Its twist in Winchester barrels was 1:12.
7.62 NATO M14 and M1A rifles had 10, 11 or 12 inch twist barrels across all makes. 7.62 M1 rifles rebuilt by the USN all had 1:12 twist 24" barrels.
7.62 NATO M14 and M1A rifles had 10, 11 or 12 inch twist barrels across all makes. 7.62 M1 rifles rebuilt by the USN all had 1:12 twist 24" barrels.
Last edited:
The original 30-06 load was 220 gr so the 10 twist made sense. By the time the 308 came on the scene much lighter bullets were the norm and most manufacturers used 12 twist in 308. In fact in my experience 308's with 10 twists are pretty uncommon. Off the top of my head the Ruger American's are the only factory rifles I can think of.
While 220's aren't common anymore in 30-06, 180's are and a lot of hand loaders shoot 200's in 30-06 for bigger game. A 10 twist may still be faster than needed, but most 30-06 rifles are bought by hunters who are very traditional thinking. A slower twist 30-06 might not have sold as well as the traditional 10.
The trend to faster 10 twist 308 barrels is recent in my observation. I think this is due to the increase in interest for longer range target shooting. Remember, it isn't really weight, but bullet length that determines stability. The longer 180-190 gr high BC target bullets fired at 308 speeds can benefit from a 10 twist.
And also in my experience the average shooter won't see any issues with lighter bullets in a 10 twist. I have 4 rifles in 308 with 10, 11, and 12 twist barrels. Certain rifles are more accurate than the others, but I can't say the barrel twist is why. The 10 twist barrel shoots 125 and 130 gr bullets more accurate than the ones with slower twists. That isn't how it is supposed to work, but in my case it does.
While 220's aren't common anymore in 30-06, 180's are and a lot of hand loaders shoot 200's in 30-06 for bigger game. A 10 twist may still be faster than needed, but most 30-06 rifles are bought by hunters who are very traditional thinking. A slower twist 30-06 might not have sold as well as the traditional 10.
The trend to faster 10 twist 308 barrels is recent in my observation. I think this is due to the increase in interest for longer range target shooting. Remember, it isn't really weight, but bullet length that determines stability. The longer 180-190 gr high BC target bullets fired at 308 speeds can benefit from a 10 twist.
And also in my experience the average shooter won't see any issues with lighter bullets in a 10 twist. I have 4 rifles in 308 with 10, 11, and 12 twist barrels. Certain rifles are more accurate than the others, but I can't say the barrel twist is why. The 10 twist barrel shoots 125 and 130 gr bullets more accurate than the ones with slower twists. That isn't how it is supposed to work, but in my case it does.
That faster twist will make some bullets, 150 grains or less, jump off the bore axis from centrifugal forces. Best accuracy is often had with reduced loads.
Jim Watson
New member
Some, not all.
I had a .30-06 that was at its most accurate with the little 130 gr Speer hollowpoint.
But the safe bet is a heavier/longer bullet.
I had a .30-06 that was at its most accurate with the little 130 gr Speer hollowpoint.
But the safe bet is a heavier/longer bullet.
All things equal and minimum across all variables, lighter weight bullets will be more accurate because they produce less rifle movement during barrel time. The line of fire cone subtends smaller angles relative to the line of sight when the primer fires.
Bore axis doesn't point to desired line of fire until the bullet clears the muzzle. That's the point above desired point of impact on target equal to bullet drop plus sight height above line of fire. It's only as repeatable as the shooter's position holding the rifle.
Last edited:
Heres just some amatuer observations with my 3 differently configured .308's
Savage 12 FTR 30" bbl 1-12". Outstanding with 155s to 178's . Never could get equal consistiency with 180+ bullets. This barrel seems to be happy with velocities somewhat near published max.
Rem R700 Varmint 26" bbl 1-12" ,. 155s and 168's , this barrel shot outstanding with more mild velocities around 2520 fps.
R600 ACC-SD. 20"bbl 1-10" . This is my heavy bullet supressor host rifle. I shoot mostly subsonic and it shoot 180-190 bullets excellent. For supersonic precision it does well with 168's but even better precision with the 178's. I shoot all said rifles at 600 yds, and shot the Savage FTR at 1000 yds but it did not shoot that well at 1K but i did reach that distance with decent precision.
Savage 12 FTR 30" bbl 1-12". Outstanding with 155s to 178's . Never could get equal consistiency with 180+ bullets. This barrel seems to be happy with velocities somewhat near published max.
Rem R700 Varmint 26" bbl 1-12" ,. 155s and 168's , this barrel shot outstanding with more mild velocities around 2520 fps.
R600 ACC-SD. 20"bbl 1-10" . This is my heavy bullet supressor host rifle. I shoot mostly subsonic and it shoot 180-190 bullets excellent. For supersonic precision it does well with 168's but even better precision with the 178's. I shoot all said rifles at 600 yds, and shot the Savage FTR at 1000 yds but it did not shoot that well at 1K but i did reach that distance with decent precision.