[cwink]

How do you determine the twist rate of your barrell.. Got a 223 and 22-250 that I want to load a little heavier bullet in say 70 grains, but not sure if what twist rate I have in the guns..

 

[nonnieselman]

What are the brands and models of the rifles?

 

[captain-03]

I have never done it; however, this seems like a simple method:

[flash=425,350]http://www.youtube.com/v/hq8DM6Do72A" allowscriptaccess="always" allowfullscreen="true[/flash]

 

[cwink]

What are the brands and models of the rifles?

The 223 is a 16" Thompson Center Contender barrell..

The 22-250 is a Ruger MK77.

 

[nonnieselman]

:cheers:

http://ruger.com/products/m77HawkeyeStandard/models.html

 

[nonnieselman]

:thumbup:

http://www.tcarms.com/firearms/chart_contender.php

 

[cwink]

Ok great, so it says the Twist rate on the 223 = 1:12 and the 22-250 is 1:14??? Am I reading that correctly?? Is that twist rate going to be to fast for the heavier bullets???

 

[nonnieselman]

my Remmy 700 in .22-250 also has a 1:14" twist.
my AR bull barrel has a 1:9" twist

I have some 68 gr bthp bullets i can try thru them and see. Never really shot many of them.

the AR shoots 55gr Vmax bullets .75 at 100yds easy. Ive loaded a few heavy bullets but didnt have many of them to do test on so i stuck with the 55gr.

 

[DBChaffin]

Yes, you are reading that correctly, but I think the problem is your twist will be too slow for the heavy bullets, not too fast.
For the .223 anyway, a 1:12" twist is versatile and will allow up to probably 60-64 gr. bullets. A faster twist is needed for heavier bullets and for the 62 grain steel core military rounds due to their length, which is as long as most 70 gr. bullets. A 1:9" twist will let you shoot up to about 73 gr. bullets. A 1:8" or even 1:7" twist is preferred for the 77 and 80 gr. bullets. Not sure on the 22-250, but I would be surprised if it wasn't nearly identical in its requirements as far as barrel twist. Velocity does play a component, so the 1:14" 22-250 may stabilize the same weight as the 1:12" .223, for example.

 

[cwink]

Yes, you are reading that correctly, but I think the problem is your twist will be too slow for the heavy bullets, not too fast.
For the .223 anyway, a 1:12" twist is versatile and will allow up to probably 60-64 gr. bullets. A faster twist is needed for heavier bullets and for the 62 grain steel core military rounds due to their length, which is as long as most 70 gr. bullets. A 1:9" twist will let you shoot up to about 73 gr. bullets. A 1:8" or even 1:7" twist is preferred for the 77 and 80 gr. bullets. Not sure on the 22-250, but I would be surprised if it wasn't nearly identical in its requirements as far as barrel twist. Velocity does play a component, so the 1:14" 22-250 may stabilize the same weight as the 1:12" .223, for example.

I have some 64 grain Soft point for the 223 that I will try and see who they work. I would like a little heavier bullet but sounds like that might not be a good idea..

 

[DBChaffin]

Yeah, from what I have read, the 64 gr. should be fine but that is about it. Some really good info here, including a chart that shows 65 gr. FB as the max bullet weight for a 1:12" twist barrel in the .223.

 

[cwink]

Finally got out there and shot the 223 with my first reloads.. The groupings were about the same as the factory loads I had, which is not my concern.. But the holes from the 62 grain Barnes TSX looked a little more ragged than the 55 grain soft point.. Could that mean the bullet is tumbleing??? Or that they are not properly stabalized??? The bullets says the twist rate should be 1:9 or faster.. May need to go down to a 55 grain.

 

[Doug Bowser]

In my experience, the .22-250 is not a good choice for heavy bullets. Accuracy suffers at velocities faster than you can get in a .223 rifle with fast twist barrels.

Doug

 

[cwink]

I am for sure going to back down on the 223.. I am shooting a 16" barrell.. I think the 55 grainers would do better..

Haven't tried the 22-250 yet.

 

[vranasaurus]

To answer your question, yes a larger or out of round hole could indicate the bullett is not completely stabilized.