When DocCoyote said he never saw any published data on 25-06 AI loads, I only pointed him to a site that had some data, and quoted one 120 gr. load mentioned. I assumed he would go to the site and look at some load data, worked up by 25-06 AI owner's. The reaction to my post was mainly something like "that one bent the needle on my BS meter", but not by all posters, most of which seemed more informed.
Now, in my Speer Reloading Manual #13, it shows an 87 gr. bullet at 3552 fps. out of a 24 in. barrel. The info below was pasted out of the "Ammo Guide" site. Compare the "Nominal Performance" of the 87 gr. bullet at 3850 fps. About a 300 fps increase in velocity. Out of my old Nosler #3 Reloading Manual from 1989, it shows a 120 gr. Nosler Partition out of a 22 in. barrel at aprox. 3100 fps. The load I quoted was shot out of a custom 24 in. Pac Nor super match barrel with aprox. a 3400 fps velocity. Also about a 300 fps increase. When you figure in the 2 in. longer barrel, and the below quotes from old P.O. Ackley himself, maybe this velocity isn't so far fetched. He quotes a lot of the things mentioned in the posts, but also mentions that the 25-06 AI still gets the most velocity out of a .25 caliber, even though over-bore.
Scroll completely down to the bottom: (I am only doing this as food-for-thought for some of the posters).
SPECIFICATIONS:
Bullet Diameter:
.257 in.
Max Overall Length:
3.250 in.
Rifling Twist:
1-in-10 in.
Rifling Lands:
Case Capacity (est):
68 gr. water
Primer Size:
.210
NOMINAL PERFORMANCE:
Bullet Weight:
87 gr.
Muzzle Velocity:
3850 f.p.s.
Muzzle Energy:
2864 ft-lbs.
"Easy Link" to this cartridge (copy and paste into emails, forums, etc.):
.25-06 Ackley Improved -
http://ammoguide.com/?catid=326
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(Above dimensions gleaned from Pacific Tool & Gauge chamber drawing #14-25/06. 40 degree shoulder variation shown.)
Formed by reducing the neck diameter of the .30-06 to .25 caliber and then fireforming, Ackley described the .25-06 Improved as "somewhat overbored" for the small diameter bullet. This means it's internal case volume is a bit too large to achieve an efficient expansion ratio, even with the use of very slow powders. As a result, increased sensitivity to charge variation may be expected between rifles. Accordingly, reloaders should always start a given load 2 or 3 grains below the recommended charge weight, and if deemed necessary, incrementally increase the charge while watching for signs of over-pressure.
Ackley was also careful to warn against the use of light loads during the fireforming process with the .25-06 Improved, describing the practice as "quite dangerous". He claimed that even though the resultant case would visually appear fully fireformed, headspacing might be short by as much as .05 inches!
For these reasons, Ackley normally recommended the smaller .257 Improved over the .25-06 Improved as being more of an "overall satisfactory cartridge" (Ackley's words). However, he did recommend the .25-06 Improved "for shooters desiring the highest velocity from the .25 bore regardless of other considerations."
The .25-06 Improved can propel an 87 grain bullet at nearly 4000 fps.
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Now, we need to hear from some actual 25-06 AI owner's and the velocities they have worked up to from this forum.
I do not have any experience with the 25-06 Rem myself and do not know what volumetric increase there actually is in the AI case, but do realize that with modern powders, primers, case preperation, and knowing that every barrel does not shoot the same velocity, many factors have to be considered. I certainly don't want to ruffle any feathers here, but thought provoking comment and different views can be appreciated by most everyone in a non beligerent way, and should be. Best regards to all poster's.
Gary
PS I do have experience with 250-3000 AI and .223 AI.