Twist Rate

[bench]

Fellas
Need help to find twist rate to stabilize Hornady 80gr GMX monolithic bullet for 6mm
I need to order a new barrel and cannot find any info.
Thanks

 

[Murray Brook]

I believe a 1/8 would do. But need more info
http://www.bergerbullets.com/twist-rate-calculator/

 

[22BRGUY]

MURRAY has it right I think

 

[Dusty Stevens]

10 would do fine, id use a 12 unless its an unusually long bullet.

 

[Curmudgeon]

How long is the plastic tip. At 1.105 length not considering the tip an 8 twist would be needed. I shoot a 75 grain tipped in a 10 twist. I use the list of lengths and stability calc. on the JBM site. Cheers

 

[bench]

From all the info I can find it looks like a 10 twist is the magic number.
As I dont like to be on the edge of twist rate I might go with a 9 twist.

 

[Baddog0302]

http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

Even has a place for the tips length

 

[Murray Brook]

In my limited testing I've found the Berger calculator give me better real world info than some of the others.

 

[22BRGUY]

From what I've read it seems that to "overspin" the bullet does not hurt anything, in fact can be helpful keeping the bullet stabilized in flight better and longer and can even help in the wind.. Unless the bullet has a very thin jacket that might come apart, I think why limit yourself when down the line you may wish to play with some heavier bullets?

 

[Webster]

Fellas
Need help to find twist rate to stabilize Hornady 80gr GMX monolithic bullet for 6mm
I need to order a new barrel and cannot find any info.
Thanks

E-Mail or phone Hornady. They are the experts. You will get 20 replies on this website.

 

[dcali]

Over-spinning hurts accuracy. Under-spinning, while still remaining stable, can result in drag due to large yaw. Grossly under-spinning will make bullets tumble. Ideally, shoot for a 1.4-1.6 Sg.

 

[bench]

So just to let everyone know I ordered a 9 twist
Hornady said they would shoot out of a 10 twist,which works out to a extra 26,000 RPM
The solid copper and zink monolithic bullet will take all extra RPM
Thanks Guys