Help Finding twist rates for various barrels?

[cavedweller]

I’m trying to find barrel twist rates for the following .177 stock platforms for inputting data into my StrelokPro APP
I really know if my numbers are correct. ?? i have conflicting info from differing sources.

Any help appreciated!

BSA Goldstar - i have conflicting info from 1:17,7 to 1:18.5. to 19 ??

Daystate Tsar - 1:17.1 ?

Daystate Revere - 1:17. ?

Daystate Redwolf - 1:17.7 ?

Daystate Alphawolf - 1:17.7 ?

Daystate Huntsman - 1:17. ?

Brocock Commander XR/XT 1:17. ?

RAW TM1000 - 1:17.7 ?

Air Arms S510 - 1:17.7 - confirmed - thank you!

Air Arms TX200 - 1:17, ?

Steyr LG110 - 1:15,75 ? Hunting Challenge HP model 2 year old model

Steyr LG100 - 1:18,75 ? 23 year old platform

Crossman 1702T pistol - 1:15,5 ?

Any help appreciated!

I found this relalted thread on GTA: https://www.gatewaytoairguns.org/GTA/index.php?topic=117383.60

 

[Nico5999]

Air Arms S510 in all calibers is 17.7" Lothar Walther Choked Poly as far as I know.

 

[Scotty1]

yes but i need the (twist rate) if it has one, for strelock pro or other app input

That IS the twist rate 1:17.7”

 

[cavedweller]

That IS the twist rate 1:17.7”

ohhh i had a brain dead moment......thank you.... i'll just keep updating the first message as new info comes in.

 

[nomojo65]

It’s pretty easy to do this your self, just use a cleaning rod “Dewey stainless or coated are best” put a tight fitting patch or brush on the handle end mark and measure then push or pull through barrel. Example would be one full turn in 17in. Is a 1-17 twist barrel. If your barrel isn’t that long math then comes into play!

 

[Scotty1]

ohhh i had a brain dead moment......thank you.... i'll just keep updating the first message as new info comes in.

Brain cramp, I get them all the time…

 

[cavedweller]

thank you.... i'll just keep updating the first message as new info comes in.

 

[cavedweller]

i did find an interesting PA thread on how twist rate affects accuracy

How does rifling twist rate affect velocity and/or accuracy? Part 13 | Pyramyd AIR Blog

by Tom Gaylord, a.k.a. B.B. Pelletier Part 1 Part 2 Part 3 Part 4 Part 5 Part 6 Part 7 Part 8 Part 9 Part 10 Part 11 Part 12 This is the summary report in this series. I'll give you my thoughts on how this test went, and I expect you to comment, as

www.pyramydair.com

 

[Ballisticboy]

You may find this post on the GTA forum of interest. It is a modelled comparison of lead and lead free pellets, but if you ignore the lead free results it shows computed group sizes for different twist rates, all else being kept constant.

External Ballistics of Pellets by Ballistician Miles Morris - Airguns & Guns Forum

External Ballistics of Pellets by Ballistician Miles Morris, Air guns, Airgun Forum

www.gatewaytoairguns.org

I have done a lot of other work on the subject, but it was all sub 12FPE for UK forums.

 

[cavedweller]

You may find this post on the GTA forum of interest. It is a modelled comparison of lead and lead free pellets, but if you ignore the lead free results it shows computed group sizes for different twist rates, all else being kept constant.

External Ballistics of Pellets by Ballistician Miles Morris - Airguns & Guns Forum

External Ballistics of Pellets by Ballistician Miles Morris, Air guns, Airgun Forum

www.gatewaytoairguns.org

I have done a lot of other work on the subject, but it was all sub 12FPE for UK forums.

Thank you!

 

[cavedweller]

You may find this post on the GTA forum of interest. It is a modelled comparison of lead and lead free pellets, but if you ignore the lead free results it shows computed group sizes for different twist rates, all else being kept constant.

External Ballistics of Pellets by Ballistician Miles Morris - Airguns & Guns Forum

External Ballistics of Pellets by Ballistician Miles Morris, Air guns, Airgun Forum

www.gatewaytoairguns.org

I have done a lot of other work on the subject, but it was all sub 12FPE for UK forums.

So i asked Igor Borisov on the Facebook StrelockPro App site:

"how important is the twist rate field numbers on a pellet gun"?

Answer:

"not very"

!!!!

 

[Spinach]

So i asked Igor Borisov on the Facebook StrelockPro App site:

"how important is the twist rate field numbers on a pellet gun"?

Answer:

"not very"

!!!!

I saw that response, I'm still scratching my head.
Speed? Perhaps the biggest factor for twist rate.

 

[Ballisticboy]

So i asked Igor Borisov on the Facebook StrelockPro App site:

"how important is the twist rate field numbers on a pellet gun"?

Answer:

"not very"

!!!!

Well, he would say that as his software does not use spin rates in a proper manner, if at all. Point mass trajectory models, which most of the readily available trajectory models are, do not use spin. Some have attempted to incorporate spin into their models in a crude way without using the necessary aerodynamic coefficients, which simply are not available. This was done on some of the early artillery fire control models about 60 years ago. The simplest trajectory model which uses spin is the Modified Point Mass which, in addition to drag coefficients, also needs spin damping, aerodynamic lift and pitching moments, yaw induced drag and pellet moments of inertia. I do not know of any models available to shooters which ask for those parameters. However, even the modified point mass model cannot calculate pellet yaw, for that you need a full 6DOF modified point mass model and all the additional aerodynamic coefficients that go with it.

The data I have produced used a 6DOF model, with the input data having been carefully produced over years and calibrated against firing results, just as is done in armed forces fire control systems. This is why the models are able to reproduce pellet spiralling and the effects of twist rate and forward speed, and why I only have it for a very few types of pellets, as it takes a long time and a lot of effort to produce.