Would appreciate some direction, I have a old style sendero in 25-06 that needs to be rebarelled.I'd like to go with the AI version in a Kreiger cut rifleing but as you guy's know the 10 twist in a factory gun doesn't work well with heavier bullets. My gun went from rifle groups to shotgun-like patterns with anything over 100gr. So thought about possibly a 9 twist instead. I'd read Kirby's post about not being able to drive the .25 fast enough to stabilise a heavy bullet, so thought about this approach,seems a simple enough fix but then I'm just the wingnut on the trigger.
Thanks in advance,any and all help appreciated. Shorty
You got it, that should fix you right up. Is the Berger 115vld the bullet you had in mind? I know a guy who shoots this bullet out of a 257 wby mag, excellent long range performance. If in doubt on twist rate, the Barnes Greenhill formula will give you a safe number (you can often get away with slower twists than recomended by formula). You don't even have to get the bullet in your hand, if a guy on the forum has one and a micrometer.
Sorry for not answering sooner, have been gone for a couple day's, but yes that was the bullet weight and type I'd wanted to use. Since I use it for coyotes to Muledeer I thought that would be a very good choice, especially at some distance with the wind blowing. Am very glad to hear that the berger works so well out of a 257Wby, I wonder how close I'll get to Wby velocity with a 25-06AI. Gonna be fun to find out! I appreciate the help Landcbeitner, I'll have to dig into the Greenhill formula since I found a website for it called Z Hat.
A 1-9 should allow you to shoot anything up to the Wildcat 130 gr bullets very well in the 25-06 AI. THis is about the heaviest bullet I recommend in this chambering for big game hunting.
Richard offers a 142 gr ULD RBBT and a 156 gr ULD RBBT and they can be made to work in the 25-06 AI but you need a 1-8 twist and they really bring the velocity potential of this chambering down. THe 130 is about max in my opinion with the 25 bore in this capacity class to retain good upper end velocities.
Krieger will cut you a 1-9, just costs a bit extra is all. This twist will still work well with all conventional weight 25 cal bullets also except for perhaps the very thin jacketed bullets but I suspect even then you would not have a problem with its velocity potential.
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