Coyboy, The length and barrel contour, really depends on what type of hunting/shooting you envisage. However, the choice of barrel manufacturer will be limited to those who make (or can make) a 1 in 7.5 or 8.0 twist barrel.
I have a custom 25/06AI, that I built for use as hunting rifle on medium game here in Australia. It was built on a Sako L61R action, Canjar Set Trigger, Shilen SS 24 inch 1 in 10 twist barrel, Fajen Laminated stock, and Bushnell Elite 4200 4-16x50 scope, and the whole rig comes in at about 8lb 12 ozs. The barrel is .610 inches diameter at the muzzle, and at a guess is probably a number 3 contour.
I recently chronographed the Wildcat 130 grain BCFBHP and 142 grain ULD in the above 25/06AI, and found that the 130 grain bullet achieved about 3150 fps and gave excellent accuracy, while the 142 grain ULD failed to stabilise keyholed into the 100 yard target due to the 1 in 10 twist. Based on the above velocities, I estimate that the 156 grain ULD bullet would probably achieve about 2900 fps. I will chronograph them when my shipment arrives in about 2 months.
I would probably choose a 26 inch barrel with 1 in 8 twist the next time that I built a 25/06AI, but if I intended to shoot the 156 grain bullet, a 1 in 7.5 twist may necessary. I suggest you seek Kirby Allens's advice (I would) on that, as he has had far more experience with the Wildcat bullets than anyone else.
While a 22 - 24 inch barrel is great for carry hunting, it is best to remember, that especially with the 142 (and 156) grain bullet, the slowest burning powders (HRetumbo, VihtN170, H870, etc) will be required to get the best accuracy and velocity balance. Consequently I believe you should choose the longest barrel that would be practical for your type of shooting. Hope the above is of some help. Brian.
For the 130s the 1-10 is fine. There are alot of guys using standard 25-06 with this bullet in the standard 1-10 twist.
The 142s will need a 1-7 or 1-8 depending on barrel maker. I say this because they are not always what they say they are. Button pulled barrels are generally a bit slower twist then their advertised numbers.
Personally for the 130s I would use a 1-10 3 groove Lilja. For the 142s I would use a 1-7 3 groove Lilja simply because that is what Dan makes that is faster then the standard 1-10.
This would also allow you to use the huge 156 gr ULD.
Personally I feel the 156 is to big for the 25-06 or its AI brother but that does not mean it can not be useful in these chamberings. We all know how the old 155 gr SMK worked in the 6.5-06 AI so this will be more of the same thing but with a much higher BC.
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
Thanks Brian and Kirby, I checked Broughtons site, they only make a 10 twist. Pac-Nor's only 8 twist is a six groove.
For this project I was thinking a #5 at 26".
Kirby if I go with Dan's 7 twist and shoot the 156's would I be better off with a 28" tube? This may be a irrelevent though, as I was thinking the 142 would be the more efficient bullet in the AI case. Does Dan chamber and thread or will I have to have it shipped to you for that? [img]/ubbthreads/images/graemlins/grin.gif[/img]