.25 heavy slug twist

[mercado]

I wanted to know from those shooting heavy. 25 slugs what is the twist used .I want to have a tj made for my AF.. that all could benefit since I have to had the tooling made.. I also since I'm already having tooling made I want to make one in .177
So for .25 is 1-15.5 .. or 1-16 ..?
For .177 .. should we try 1-8 or 1-9 .. 1-9 is the twist used to shoot 26gr cast slugs in .172 .. I really don't see my self buying many more guns but .. I could have plenty of different barrels to play with my AF guns.

 

[JaceSpace1369]

I wanted to know from those shooting heavy. 25 slugs what is the twist used .I want to have a tj made for my AF.. that all could benefit since I have to had the tooling made.. I also since I'm already having tooling made I want to make one in .177
So for .25 is 1-15.5 .. or 1-16 ..?
For .177 .. should we try 1-8 or 1-9 .. 1-9 is the twist used to shoot 26gr cast slugs in .172 .. I really don't see my self buying many more guns but .. I could have plenty of different barrels to play with my AF guns.

Does the necessary twist rate for a projectile size get determined by the velocity or it the only determining factor the length and weight of the projectile?

I have both a 17hmr and a 17wsm, both are 1/9 twist rate, I think my 17wsm is supposed to be a 1/8 due to the faster velocity but I'd have to look into it again.

Either way, I've found that .177 16hr slugs work well down to 1:17.7 twist, and the 20gr zan slugs are working for guys shooting with 1:16 twist barrels as well 1:14 twist. But then again that's .177 and not .172 like you mentioned.

How fast are you going to sling this bullet?

 

[JaceSpace1369]

I wanted to know from those shooting heavy. 25 slugs what is the twist used .I want to have a tj made for my AF.. that all could benefit since I have to had the tooling made.. I also since I'm already having tooling made I want to make one in .177
So for .25 is 1-15.5 .. or 1-16 ..?
For .177 .. should we try 1-8 or 1-9 .. 1-9 is the twist used to shoot 26gr cast slugs in .172 .. I really don't see my self buying many more guns but .. I could have plenty of different barrels to play with my AF guns.

Also how long are these slugs? The .172

 

[mercado]

Does the necessary twist rate for a projectile size get determined by the velocity or it the only determining factor the length and weight of the projectile?

I have both a 17hmr and a 17wsm, both are 1/9 twist rate, I think my 17wsm is supposed to be a 1/8 due to the faster velocity but I'd have to look into it again.

Either way, I've found that .177 16hr slugs work well down to 1:17.7 twist, and the 20gr zan slugs are working for guys shooting with 1:16 twist barrels as well 1:14 twist. But then again that's .177 and not .172 like you mentioned.

How fast are you going to sling this bullet?

Thank you.. AF platform there is almost no limit. It will not be hard to shoot a 26 to 28gr 1000fps + In low power will verify the cast bullet length I really have no idea.. what gun have 1-14 n 1-16 .. twist in 177

 

[mercado]

Also how long are these slugs? The .172

.493 that is the length of 26gr in 172 .. but the barrel will be made in 177 .. just wanted to have a general idea.. with the barrels made .. having slugs done will be the easy part ..

 

[Scotchmo]

TJ already sells a 1:14 twist 25 Auto liner that should work good with 60gr+ slugs.

 

[JaceSpace1369]

.493 that is the length of 26gr in 172 .. but the barrel will be made in 177 .. just wanted to have a general idea.. with the barrels made .. having slugs done will be the easy part ..

The fx panthera sells their 600mm with a 1:16 twist. I'm getting a 450mm alpha precision barrel that comes in 1:14 twist, that I thought would work for those really heavy slugs, but I guess it's going to be pretty much trial and error.

For what you're trying to shoot 1:9 twist would be good, but 1:8 would be better.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

This is the data I got with the info you gave along with a guesstimate of the bc, weather and average altitude in PR.

 

[mercado]

The fx panthera sells their 600mm with a 1:16 twist. I'm getting a 450mm alpha precision barrel that comes in 1:14 twist, that I thought would work for those really heavy slugs, but I guess it's going to be pretty much trial and error.

For what you're trying to shoot 1:9 twist would be good, but 1:8 would be better.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

This is the data I got with the info you gave along with a guesstimate of the bc, weather and average altitude in PR.

I appreciate it thanks..

TJ already sells a 1:14 twist 25 Auto liner that should work good with 60gr+

TJ already sells a 1:14 twist 25 Auto liner that should work good with 60gr+ slugs.

Thank you..

 

[JaceSpace1369]

I appreciate it thanks..



Thank you..

You're welcome

 

[davhowrd]

TJ already sells a 1:14 twist 25 Auto liner that should work good with 60gr+ slugs.

From my experience, those TJ barrels that I have are GREAT with 44 to 56gr slugs running 940 fps to 1120 fps. Smoking!

 

[LDP]

Does the necessary twist rate for a projectile size get determined by the velocity or it the only determining factor the length and weight of the projectile?

Velocity does play a role. Theres a bottom end velocity for a twist rate to work in stabilizing a given projectile. If you drop below that velocity threshold for that projectile you have to increase twist rate.
Example using FX hybrid .25 slugs @ 26 gr. Barrel twist 1: 20
@ 1000 fps the calculator shows stable with an SG of 1.54
@ 700 fps the calculator shows unstable with an SG of 1.37 and suggests a minimum barrel twist of 1: 13 to properly stabilize this projectile @ 700 fps.

 

[JaceSpace1369]

Velocity does play a role. Theres a bottom end velocity for a twist rate to work in stabilizing a given projectile. If you drop below that velocity threshold for that projectile you have to increase twist rate.
Example using FX hybrid .25 slugs @ 26 gr. Barrel twist 1: 20
@ 1000 fps the calculator shows stable with an SG of 1.54
@ 700 fps the calculator shows unstable with an SG of 1.37 and suggests a minimum barrel twist of 1: 13 to properly stabilize this projectile @ 700 fps.

Is this what causes destabilization down range at long ranges?

 

[LDP]

Is this what causes destabilization down range at long ranges?

It could. As the projectile loses spin its going to lose stabilization as well. Pellets are less prone since they are drag stabilized so they remain stable to lower velocities.
Using the same comparison as earlier but switching to a 1: 18 twist that slug remains above a SG of 1.5 well beyond 300 yds. The slug would have to drop below 500 fps before its no longer considered stabilized. That slug drops to 500 fps @ 500 yds starting at 985 fps. So well beyond what most people are going to try and push it.

 

[RM.510bigbore]

I wanted to know from those shooting heavy. 25 slugs what is the twist used .I want to have a tj made for my AF.. that all could benefit since I have to had the tooling made.. I also since I'm already having tooling made I want to make one in .177
So for .25 is 1-15.5 .. or 1-16 ..?
For .177 .. should we try 1-8 or 1-9 .. 1-9 is the twist used to shoot 26gr cast slugs in .172 .. I really don't see my self buying many more guns but .. I could have plenty of different barrels to play with my AF guns.

Check out Redman Gun Barrel liners...They have .172 liner with 9 twist standard..25 inch finished price $50.00..They have 9 twist .223 barrels also...$50.00... They barrels are sold through brownells too...only .223 16 twist for$38.00 and $10.00 shipping.... Two barrels for$100.00 dollars cheaper than airgun slugs . I think you could sleeve pretty easy with 12 mil outside and 8 mil inside carbon fiber sleeve... Put factory 12 mil Airforce bushing on top of sleeve...

 

[JaceSpace1369]

I wanted to know from those shooting heavy. 25 slugs what is the twist used .I want to have a tj made for my AF.. that all could benefit since I have to had the tooling made.. I also since I'm already having tooling made I want to make one in .177
So for .25 is 1-15.5 .. or 1-16 ..?
For .177 .. should we try 1-8 or 1-9 .. 1-9 is the twist used to shoot 26gr cast slugs in .172 .. I really don't see my self buying many more guns but .. I could have plenty of different barrels to play with my AF guns.

To add to this, my vulcan 3 has a 1:17.7 twist 700mm barrel in .25 and shoot 36gr slugs and up really well. Like up to 46gr H&N cause I haven't tested heavier slugs