260 rem. twist ?
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Re: 260 rem. twist ?
Some say 8.5, some say 8. Depends if you come from the school which says to be very careful to not use more twist than just needed or if you come from the school which says to make sure to have enough twist for all situations such as cold weather or sea level or using a can and want to minimize baffle strikes.
Some say 8.5, some say 8. Depends if you come from the school which says to be very careful to not use more twist than just needed or if you come from the school which says to make sure to have enough twist for all situations such as cold weather or sea level or using a can and want to minimize baffle strikes.
Re: 260 rem. twist ?
I would normally favor the minimum twist needed to stabilize my heaviest expected bullet. I usually do this to minimize the potential for blowing up bullets at the lightweight end of the spectrum.
But experiments with 95gr Hornady V-Max going 3400fps+ out of a 28" 1:8" barrel have allayed my fears about such self destructions. I no longer have any qualms about 1:8" twists for the .260.
As a caveat, i have also experienced strange ballistic performances from midweight bullets at extreme distances, indicating a possible nose-over/yaw issue resulting in consistently observed significantly exaggerated drop. My conclusion is simply that for longer distances the heavier bullets have good reasons for being preferred, and that for lighter weight bullets at such distances, slower twists have advantages.
Greg
I would normally favor the minimum twist needed to stabilize my heaviest expected bullet. I usually do this to minimize the potential for blowing up bullets at the lightweight end of the spectrum.
But experiments with 95gr Hornady V-Max going 3400fps+ out of a 28" 1:8" barrel have allayed my fears about such self destructions. I no longer have any qualms about 1:8" twists for the .260.
As a caveat, i have also experienced strange ballistic performances from midweight bullets at extreme distances, indicating a possible nose-over/yaw issue resulting in consistently observed significantly exaggerated drop. My conclusion is simply that for longer distances the heavier bullets have good reasons for being preferred, and that for lighter weight bullets at such distances, slower twists have advantages.
Greg
Re: 260 rem. twist ?
All I have ever had were 1:8" barrels, so I can't comment reliably beyond that. If I had my cohices, I'd have a 1:8" dedcated for LR and 140-ish bullets, and a 1:10" for 129gr (SST's) and lighter.
Greg
All I have ever had were 1:8" barrels, so I can't comment reliably beyond that. If I had my cohices, I'd have a 1:8" dedcated for LR and 140-ish bullets, and a 1:10" for 129gr (SST's) and lighter.
Greg
Re: 260 rem. twist ?
Based on all of the threads I have read, most people are having more success with the 1:8.5 twist than the 1:8. Go look at the reloading thread. There are a lot of people doing well with both. I briefly researched the difference when I had my last 260 built. I leaned heavily toward the 1:8.5 twist.
My 140 Bergers say 1:8 twist on the box. They stabilize fine with 1:8.5.
I am by no means an expert, but based on the vast majority of information I found when I was researching you can't go wrong with a 1:8 or 1:8.5. The 1:8.5 does seem to have an edge based on results in the reloading threads.
Search and make your own decision. I don't think you can go wrong either way. If you want to shoot a heavier bullet I wouldn't personally go with a 1:9.
Based on all of the threads I have read, most people are having more success with the 1:8.5 twist than the 1:8. Go look at the reloading thread. There are a lot of people doing well with both. I briefly researched the difference when I had my last 260 built. I leaned heavily toward the 1:8.5 twist.
My 140 Bergers say 1:8 twist on the box. They stabilize fine with 1:8.5.
I am by no means an expert, but based on the vast majority of information I found when I was researching you can't go wrong with a 1:8 or 1:8.5. The 1:8.5 does seem to have an edge based on results in the reloading threads.
Search and make your own decision. I don't think you can go wrong either way. If you want to shoot a heavier bullet I wouldn't personally go with a 1:9.
Re: 260 rem. twist ?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TDH</div><div class="ubbcode-body">My 140 Bergers say 1:8 twist on the box. They stabilize fine with 1:8.5.</div></div>
Twist selection requires specifying the temp and muzzle velocity.
You are in the South. To me that means you shoot in warm weather. I know the military likes to test at -40 or maybe -20 degrees F, but I will set this up for 0 degrees F worst-case.
People tend to shoot 24 inch or longer barrels in this caliber. That means at least 2700 fps.
http://accurateshooter.net/Blog/millerformula.xls
For the Sierra 142, the stability factor with these settings and 8.5 twist is 1.32. That is below the recommended 1.4, but it should be ok most of the time.
8 twist gives 1.49. That is safer.
But if you are using a 26 inch barrel with hot loads, and shooting for competition and not using a silencer where baffle strikes are a main concern - then 8.5 twist may be the best choice.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TDH</div><div class="ubbcode-body">My 140 Bergers say 1:8 twist on the box. They stabilize fine with 1:8.5.</div></div>
Twist selection requires specifying the temp and muzzle velocity.
You are in the South. To me that means you shoot in warm weather. I know the military likes to test at -40 or maybe -20 degrees F, but I will set this up for 0 degrees F worst-case.
People tend to shoot 24 inch or longer barrels in this caliber. That means at least 2700 fps.
http://accurateshooter.net/Blog/millerformula.xls
For the Sierra 142, the stability factor with these settings and 8.5 twist is 1.32. That is below the recommended 1.4, but it should be ok most of the time.
8 twist gives 1.49. That is safer.
But if you are using a 26 inch barrel with hot loads, and shooting for competition and not using a silencer where baffle strikes are a main concern - then 8.5 twist may be the best choice.
Re: 260 rem. twist ?
ok thanks guy ,
my barrel is a Krieger #17 Heavy Varmint contour 1-8 twist stainless barrel finished at 27 inches.
ok thanks guy ,
my barrel is a Krieger #17 Heavy Varmint contour 1-8 twist stainless barrel finished at 27 inches.
Re: 260 rem. twist ?
My 260 upper is a 24" barrel adn stabilizes the 123 and 140 Amax without a problem, however, I've never shot it below 50F and 800' ASL.
It's a factory DPMS barrelin 8.5 twist. The early gen lR260's had 7.5 twist barrels and a buddy has that one. His rifle shoots anything we push through it, including 160 RN's.
We built him a 6.5-06 with an 8 twist and throated for 140 Bergers, they are stable at 2700 fps in 1800' ASL and 25*F weather. We started working loads up and the first ones shot very well, they're just slow. By the time we finished they are more like 3200+
My 260 upper is a 24" barrel adn stabilizes the 123 and 140 Amax without a problem, however, I've never shot it below 50F and 800' ASL.
It's a factory DPMS barrelin 8.5 twist. The early gen lR260's had 7.5 twist barrels and a buddy has that one. His rifle shoots anything we push through it, including 160 RN's.
We built him a 6.5-06 with an 8 twist and throated for 140 Bergers, they are stable at 2700 fps in 1800' ASL and 25*F weather. We started working loads up and the first ones shot very well, they're just slow. By the time we finished they are more like 3200+
Re: 260 rem. twist ?
8.5 for 123 works great
8.0 better for 140-142 and up
plus with a 260 you have enough power to drive them fast enough
8.5 for 123 works great
8.0 better for 140-142 and up
plus with a 260 you have enough power to drive them fast enough
Re: 260 rem. twist ?
I have built a bunch of 6.5's and all have had 1-8" and that has worked very well for 123g Scenars, 130 Berger VLD's, and 139 Scenars. I have two more 6.5 blanks on the shelf and they are both in 1-8".
wade
I have built a bunch of 6.5's and all have had 1-8" and that has worked very well for 123g Scenars, 130 Berger VLD's, and 139 Scenars. I have two more 6.5 blanks on the shelf and they are both in 1-8".
wade
Re: 260 rem. twist ?
I have a new sako .260 (1:8") and have been experimenting with 120g fed fusion and 140g remington premier corelokt factory ammo. This is alI I have shot so far and I can't say whether its due to the weight or other factors but the 140g's are well sub-moa while the 120s are very inconsistent.
I have a new sako .260 (1:8") and have been experimenting with 120g fed fusion and 140g remington premier corelokt factory ammo. This is alI I have shot so far and I can't say whether its due to the weight or other factors but the 140g's are well sub-moa while the 120s are very inconsistent.
Re: 260 rem. twist ?
I have been verifying this, alternating groups of three, the 140g groups are <1" at 100y and the 120g groups are >3" (negligible wind).
One thing that makes me think it's not just inconsistent loads in the cheaper fed fusion is that there is more variance with the 120g's in both the horizontal and vertical plane. Would a fast rate of spin do this to the lighter bullets?
I have been verifying this, alternating groups of three, the 140g groups are <1" at 100y and the 120g groups are >3" (negligible wind).
One thing that makes me think it's not just inconsistent loads in the cheaper fed fusion is that there is more variance with the 120g's in both the horizontal and vertical plane. Would a fast rate of spin do this to the lighter bullets?
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