308 rate of twist
#2
Nontypical Buck
Join Date: Feb 2003
Location: west central wi USA
Posts: 2,242
A slower rate of twist will work better with shorter(lighter) bullets. Typically a .308 would have a 1:12 twist. But I've heard of more rifles with the same twist as a 30-06, 1:10, to be accurate with a wider variety of bullet weights.
#3
From Shilen's website:
.308
- 8" for bullets heavier than 220gr.
- 10" for bullets up to 220gr.
- 12" for bullets up to 170gr.
- 13"* Ratchet rifled 4 groove
- 14"* for bullets up to 168gr.
- 15"* for bullets up to 150gr.
- 17"* for bullets up to 125 gr.
.308
- 8" for bullets heavier than 220gr.
- 10" for bullets up to 220gr.
- 12" for bullets up to 170gr.
- 13"* Ratchet rifled 4 groove
- 14"* for bullets up to 168gr.
- 15"* for bullets up to 150gr.
- 17"* for bullets up to 125 gr.
#4
at what muzzle velocity? velocity also plays a roll in bullet stabilization
an 8 twist at 2300 fps will spin a bullet 207,000 rpm's
a 10 twist at 2800 will do 201,600 rpm's
a 12 twist at 3350 fps will do 201,000 rpm's
so if a 308 will stabilize a 230 gr at a max load, then a 300 rum will do it with a 12 twist and a 300 wsm will do it with a 10, do any makers give you a velocity window for these reccomended twists?
RR
an 8 twist at 2300 fps will spin a bullet 207,000 rpm's
a 10 twist at 2800 will do 201,600 rpm's
a 12 twist at 3350 fps will do 201,000 rpm's
so if a 308 will stabilize a 230 gr at a max load, then a 300 rum will do it with a 12 twist and a 300 wsm will do it with a 10, do any makers give you a velocity window for these reccomended twists?
RR
#5
Nontypical Buck
Join Date: Aug 2007
Location: WY
Posts: 2,056
Okay, I'm not sure where a question about a .308 has introduced the possibility of a "magnum"...
If you're shooting a .308, it depends upon your intended use. If the heaviest bullet you intend to send downrange is 150 grains, a 1:12 would be fine. If you're sending something 175-178 grains and heavier, you need to lean toward 1:10. I know a lot of guys who are shooting .308s with 1:11 (and fractions) as a compromise, but I don't see that they work quite as well as a 1:12 with light bullets, or a 1:10 with heavy bullets.
If you're shooting a .308, it depends upon your intended use. If the heaviest bullet you intend to send downrange is 150 grains, a 1:12 would be fine. If you're sending something 175-178 grains and heavier, you need to lean toward 1:10. I know a lot of guys who are shooting .308s with 1:11 (and fractions) as a compromise, but I don't see that they work quite as well as a 1:12 with light bullets, or a 1:10 with heavy bullets.