I have had some experience with the Ackley line of improved cartridges. I have had a 250 AI, about a dozen 257 AI, a couple of 7MM AI's and 4 '06 Ackleys. The improvement is much more pronounced in the smaller case as opposed to the 06. GB is correct in the increased case life and it is by a considerable margin. Also a large majority of the rifles I've had showed some improvement in accuracy, the lone exception was in the '06. It didn't change the grouping in any of the 06's. The smaller cases suddenly became less "fussy" to load for. Regarding the velocity increase with improved cartridges, the smaller the case the greater the gain. MY 250 showed about 200fps gain, the 257's about 100 to 150, the 7MM only about 100 and the '06's not any measurable gain. The '06 just required more power to reach the same velocities. It did allow for the use of slower burning powders however. The real drawback has been almost all actions (bolt) will have to be altered to feed without problems. :?