About barrel twist rate?

[33rowdy]

I just bought this Savage Axis 223. It has a 1-9" twist barrel. I never loaded for this caliber in this fast of a twist rate. All 9 of my reloading manuals use a test gun of a twist rate of 1-12" and one with a 1-14. So my question is; will the difference in twist rate effect muzzle velocity?

The goal is that I can zero this gun at 200 yards with my handy 100 yard range. Then I can use a ballistic chart or calculator to adjust from their.

 

[jmorris]

The faster rate is better for longer/heavy bullets. Some thin jacketed varmit bullets come apart but with the kajillion AR's out there with 1:7-1:9 barrels they are less common today than they were in the past.

200 is nothing for a 223 but if you don't test a chart is only a good guess.

 

[Cemetery21]

Theoretically, a faster twist could offer a little more resistance. But, if you are using published data to determine your muzzle velocity, the twist rate will not matter. Two barrels with the same specs will usually have different muzzle velocities. You might be within 150 fps, up or down, from the book, if you have the same length barrel.
The only way to know your muzzle velocity (with given load on a given day) is a chronograph.
But, if you are just looking to guesstimate the 200 yard impact (with a 223), a difference of 150 fps isn't going to make much difference at that range. So, use the book, if you don't have access to a chronograph, sight in at 100 and check it at 200 when you have a chance.

 

[33rowdy]

Thank you Cemetery21!

That was what I was looking for. A 200 yard target is in the future, but my 100 yard target is what I have at my front door now. A chronograph is on my shopping list.

 

[Cemetery21]

You are welcome, sir.
You might play with this tool some to see that precise velocity figures may not be required at 200. For example, a 55 gr. at 3200 hits about .6" higher at 200 than the same bullet at 3000 (both dead on at 100). If you can hold a 1/2" group at 200, you are probably better than most of us.

http://www.handloads.com/calc/index.html

 

[tlen]

Twist rate has to do with allowable bullet weights, not velocity.
http://www.shilen.com/calibersAndTwists.html

 

[33rowdy]

Thanks again Cemetery21. I was playing with this one. I'll look at that one also.

http://www.hornady.com/ballistics-resource/ballistics-calculator