Anytime someone is talking bullet choice with 204,223,22-250, etc. We always talk about twist rate. But it seems when asked about bullets for larger like (.308) 150g, 165,168,180. The term twist rate hardly ever seems to pop up. Is it not as big of a factor with the larger rounds?
Why is this
- Thread starter getfoxy
- Start date
Jack Roberts
Moderator - Deceased
There is a lot more difference in length between the shortest and longest bullets in the smaller calibers.
Jack
Jack
Happy_Hunter
New member
Along with what Jack said (of which I do agree) I also think its because many people use projectiles in 22 cal rounds that are closer to the longest that a twist is designed for. Many people shoot 55gr in 22-250 and most 22-250s are 1:14. Go to 60gr and you probably won't stabilise it. Savage accounted for this many years ago by applying a 1:12" twist for their 22-250s.
Whereas, a 308 in many cases is designed to shoot a 168gr pill, but many people shoot 150gr pills.
Whereas, a 308 in many cases is designed to shoot a 168gr pill, but many people shoot 150gr pills.
RonO.
New member
According to "Load from a disc" program, a .308 with a 1 in 10" twist will stabilize bullets up to 200 grain HPBT Sierra bullets. Even having seen it on my own computer screen I find that hard to believe, but there it is.
Just double checked and if a 220 grain RN flat based Sierra tickles your fancy, a 1 in 10" will be enough.
Just double checked and if a 220 grain RN flat based Sierra tickles your fancy, a 1 in 10" will be enough.
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RonO.
New member
Definitely. One of the reasons that the 30 calibers are pretty standard with 1 in 10" twists is that the 30-40 Krag was adopted with a 220 grain bullet. The military being what it was kept the barrel specs and moved up to the 30-03 (also with 220 grn bullet) and then the 30-06.
The 5.56 is the only military cartridge I can think of that has covered so much ground in regards to rates of twist and bullet weight.
The 5.56 is the only military cartridge I can think of that has covered so much ground in regards to rates of twist and bullet weight.
mark shubert
New member
Ron O, Is that with a round nosed bullet, or a spitzer? It's the length of the bullet, not the weight, that makes the difference.
Mark
Mark
RonO.
New member
The 200 grain example was a HPBT, a spitzer bullet. The 220 grain example was for a RN flat based bullet. As I looked through examples using "Load From a Disc" it was interesting that where a 200 grain Sierra spitzer with a boat tail base required a 1 in 11" twist, a Speer 200 grain spitzer bullet with a flat base required only a 1 in 12" twist. You are right in saying that bullet length is the key. For example, a Barnes TSX flat based bullet at the same 2500 fps velocity in the examples above would require a 1 in 9" rate of twist.
Originally Posted By: getfoxyHmm those whitetails around here don't need a 220g lol. I'm just mainly wanting to shoot 150,165,168 and maybe 180. Basically though a 10 twist will be fine for these weights, right?
I have found the 240gr. Sierra MK to be excellent p-dog medicine....especially when the ground is nice and hard. The rifle that likes that bullet is a .30-06 with a 30" Krieger 1:7.5".
John
I have found the 240gr. Sierra MK to be excellent p-dog medicine....especially when the ground is nice and hard. The rifle that likes that bullet is a .30-06 with a 30" Krieger 1:7.5".
John