hey, my apologies this has probably been asked many times before but i couldn't seem to find anything specific to my question (probably looking in the wrong spot), anyway my question is what is the best way to work out an ideal barrel twist rate for a purpose. i know i can just go online and see what everyone else is using but someone had to be the first guy to work it out right? im looking at using either a 140 or 147 ELD match in 6.5 creedmoor for target shooting Just for some context to my question. cheers guys
Barrel twist rate
- Thread starter Sheppard391
- Start date
Knowing what bullet you want to shoot is a good starting place. Then, experiment with stability calculators like the one from JBM to see what twist rate + muzzle velocity will give you stable bullet flight.
https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
For the 140 ELD-M in 6.5CM, you are fine with a 1:8 twist.
https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
For the 140 ELD-M in 6.5CM, you are fine with a 1:8 twist.
Another option is to pick your preferred bullet and contact the manufacturer tech support. Ask for the recommended twist rate and muzzle velocity for the chosen projectile. They almost always are great at giving out that information.
Bringing this to the top with my question. My new (to me) 300 wsm has a 1:11 twist. All of the specs I see on these threads and on Mfr websites talk about much faster twists like 1:8.
What will be the consequences or bullet limitations of my 1:11 twist?
Talking only factory ammo for me. I have been using 150 gr Winchester ballistic silvertip on my other 300 wsm, a sako finnlight, and was just going to stay with that for starters.
What will be the consequences or bullet limitations of my 1:11 twist?
Talking only factory ammo for me. I have been using 150 gr Winchester ballistic silvertip on my other 300 wsm, a sako finnlight, and was just going to stay with that for starters.
I am running 190 vlds in an 11 twist with very good results.
Thanks for the quick answer - but it leads me to two questions -
Why would somebody shoot such heavy bullets, or why might I want to? Is that how much weight it takes to make the long super-ballistic bullets with less wind drift?
What is the advantage of slower twist? Why not make them all 1:8 or faster so they can shoot any bullet?
Sorry, my questions might belong down in the stupid question forum.
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more energy on target
higher BC means less drop and/or less wind
but there is a point where too heavy is simply too heavy for the powder pushing it
you can overspin bullets and make them explode just by too many RPMs. and with extra speed you can also use a slightly slower twist. play with the berger stability calculator
a stock 300WSM is meant for hunting. not target shooting. so a 150 or even 175 will be fine from an 11 twist
look at a 22-250 with a 9 or 12 twist? it cant take advantage of 88 or 90 or 95gr bullets until you get to a 7 twist
higher BC means less drop and/or less wind
but there is a point where too heavy is simply too heavy for the powder pushing it
you can overspin bullets and make them explode just by too many RPMs. and with extra speed you can also use a slightly slower twist. play with the berger stability calculator
a stock 300WSM is meant for hunting. not target shooting. so a 150 or even 175 will be fine from an 11 twist
look at a 22-250 with a 9 or 12 twist? it cant take advantage of 88 or 90 or 95gr bullets until you get to a 7 twist
I believe the original question was for a 6.5 Creedmoor running 140 or 147 grain ELD bullets. The "normal" twist on a 6.5 Creedmoor barrel is 1 in 8, and that is just fine for running the 140 or 147 grain bullets.
Some competitors are starting to run 1 in 7.5 barrels in 6.5 creedmoor but that is typically to run bullets in the 150 or higher grain range like the new 150 grain Sierra Match King. Then there are also "gain twist" barrels that can run a wider variety of weights.
Some competitors are starting to run 1 in 7.5 barrels in 6.5 creedmoor but that is typically to run bullets in the 150 or higher grain range like the new 150 grain Sierra Match King. Then there are also "gain twist" barrels that can run a wider variety of weights.
I went with a Bartlien 1-7.5 twist for my first 65CM build.
After a lot of reading and research I figured it would allow me to use the heaviest offerings and wouldn't handicap me if I wanted to run the 130 class of bullets.
Part of the decision was also that I had no intention to run a really long barrel and settled on 23" as it seemed the best combination of compact and balance without giving up much performance.
With the 150smk loaded with a moderate charge of H4350 at 41.2 grains and .015" jump in new Lapua brass averaged 2675fps.
After a lot of reading and research I figured it would allow me to use the heaviest offerings and wouldn't handicap me if I wanted to run the 130 class of bullets.
Part of the decision was also that I had no intention to run a really long barrel and settled on 23" as it seemed the best combination of compact and balance without giving up much performance.
With the 150smk loaded with a moderate charge of H4350 at 41.2 grains and .015" jump in new Lapua brass averaged 2675fps.
