Would like some "real life" feedback regarding the best twist rate to go with for shooting both 120 and 140 gr bullets in a 260 Rem. Which twist would be best for this range of bullets 1:8 or 1:9 ? Would using a 1:8 cause accuracy problems with the shorter bullets?
Optimum twist rate for a 6.5
- Thread starter JEC
- Start date
From what I read and have seen 1:8" handles 120-160gr without any issues. Recommended for larger cases such as 6.5x55 and 6.5x.284 more often as you use 139-142gr bullets and able to push them @ 2800+fps.
While 1:9" designed for 107-140gr and will do 107-130grs best. .260 and 6.5x47 as most is most usefull with 120-130gr for competition and is able to push those @ 2800+fps.
While 1:9" designed for 107-140gr and will do 107-130grs best. .260 and 6.5x47 as most is most usefull with 120-130gr for competition and is able to push those @ 2800+fps.
Best bullet for 1:9...................260 Rem
I have learned a lot since asking about twist rates and have still not decided....what is best.
To date, I am convinced that the 1:9 twist will handle most bullets ranging from 107 gr to 140....depending upon the length of the bullet. For instance, a "match/varmint" profile in a light (107 gr) bullet is long enough to perform well with the 1:9 twist. That seems to apply to all the "pointed profile" bullets up to 140 gr..... After that, a 1:8 twist would be best. Given that not many 260 owners will use bullets over 140gr, I suspect the 1:9 is quite adequate at stabilizing most bullets. "Game profile" bullets are ususally less pointed and therefore even the heavy 140' can be easily stabilized by 1:9.
Then, there is the question of loading a long (pointed) 140 gr bullet in the 260 case given that most 260's are not "long throated" like the 6.5 X 65 and therefore, the long bullet may protrude further into the case than some reloaders want.
I am still trying to find out the effect of spinning a bullet too fast (over-rotating). It seems that a fair amount of over rotation can be tolerated without adverse results unless the bullet is not concentric...and then the lack of concentricity is amplified. This would mean that 1:8 twist might over rotate a 107gr bullet and if it was not concentric...cause it to lose stability.
Then, there is the issue of velocity ... The higher the velocity, the faster the bullet spins. This may become a factor when muzzle velocities exceed 2800fps.
Well, I still haven't figured out the answer! In the end, it is testimonials from folks who actually have expeience with the twists and bullets that are most helpfull. Sometimes, there is just no substitute that has the credibility of real experience!
I have learned a lot since asking about twist rates and have still not decided....what is best.
To date, I am convinced that the 1:9 twist will handle most bullets ranging from 107 gr to 140....depending upon the length of the bullet. For instance, a "match/varmint" profile in a light (107 gr) bullet is long enough to perform well with the 1:9 twist. That seems to apply to all the "pointed profile" bullets up to 140 gr..... After that, a 1:8 twist would be best. Given that not many 260 owners will use bullets over 140gr, I suspect the 1:9 is quite adequate at stabilizing most bullets. "Game profile" bullets are ususally less pointed and therefore even the heavy 140' can be easily stabilized by 1:9.
Then, there is the question of loading a long (pointed) 140 gr bullet in the 260 case given that most 260's are not "long throated" like the 6.5 X 65 and therefore, the long bullet may protrude further into the case than some reloaders want.
I am still trying to find out the effect of spinning a bullet too fast (over-rotating). It seems that a fair amount of over rotation can be tolerated without adverse results unless the bullet is not concentric...and then the lack of concentricity is amplified. This would mean that 1:8 twist might over rotate a 107gr bullet and if it was not concentric...cause it to lose stability.
Then, there is the issue of velocity ... The higher the velocity, the faster the bullet spins. This may become a factor when muzzle velocities exceed 2800fps.
Well, I still haven't figured out the answer! In the end, it is testimonials from folks who actually have expeience with the twists and bullets that are most helpfull. Sometimes, there is just no substitute that has the credibility of real experience!
lejarretnoir
CGN Ultra frequent flyer
- Location
- 162km from Connaught
From real experience and having shot several 6.5's in both 1-8" to 1-9" and worn them out, stick with the 1-8". It will do anything the 1-9" can do with any bullet you put in it and outstanding accuracy. Why limit yourself when you can use long VLD type bullets too.
You cannot overstabilize any 6.5 bullet I've seen and I have used 85gr in a 1-8".
You cannot overstabilize any 6.5 bullet I've seen and I have used 85gr in a 1-8".
X2! I now opt for the 1-8" twist in any 6.5 I put together. Regards, Eagleye.
In theory a bullet can be over stabalized. This creates problems at long range, but if loading for long range one would use a long heavy bullet - which would not be over stabalized.
An over stabalized bullet will not tip over as it starts back down towards the target. It comes down still pointed up as it left the barrel.
The diffference in barrel quality from one maker to the next is probably a much bigger issue than the twist (1:9 vs 1:8). And the differences between chambering quality from one gunsmith to the next are big variables - so trying to attribute good results to twist is wishful thinking.
All my custom 6.5s are 1:8.
An over stabalized bullet will not tip over as it starts back down towards the target. It comes down still pointed up as it left the barrel.
The diffference in barrel quality from one maker to the next is probably a much bigger issue than the twist (1:9 vs 1:8). And the differences between chambering quality from one gunsmith to the next are big variables - so trying to attribute good results to twist is wishful thinking.
All my custom 6.5s are 1:8.
