I too have been working with a .30-30 Ackley Improved. My started life as a Super 14, 6 Land & Groove, 1 in 14" Twist .30 Herrett Barrel. SSK Industries did the rechamber for me, and I am quite pleased with their work. The turn aroiund time from SSK for this service was only a couple weeks.
I have only tested two bullets so far.
First was the 125gr. Nosler Ballistic Tips. With this bullet I tested 5 different powders, IMR-4198, H-4198SC, H-322, AA #2230, and W-748. The prefered load uses IMR-4198 (just like Shortgun said it would), and is producing 2683 FPS average Velocity in my 6 Land & Groove, 1 in 14" Twist Barrel. The extreme spread of 5 rounds over the chronograph was 57 FPS, with a Standard Deviation of 9.59. The average groups size at 100 yards for 5 shot groups is .673". Cases fall right out of the chamber. The charge is below the MAX listed in P.O. Ackley's Handbook for Shooters and Reloaders.
With the 150gr. Nosler Ballistic Tip, again I borrowed Shortgun's Load for this one, which uses IMR-3031 Powder. The charge is again below the MAX listed in P.O. Ackley's Handbook for Shooters and Reloaders. Average Velocity for the 150's was an amazing 2437 FPS, with an Extreme Spread of 50 FPS, and a Standard Deviation of 9.38. Accuracy with this one wasn't as good as the 125's, but is still quite good enough for Whitetails. The average for the 100 yard 5 shot groups came in at 1.462" for the 150's.
I am not sure if there is anything to it or not, but I have always heard that the Old Style 6 Land & Groove, 1 in 14" Twist Barrels produced higher velocities and and don't build pressures as fast as the Newer Style Equal Land & Groove, 8 Land & Groove 1 in 10" Twist Barrels. If indeed there is something to this, this could account for the added velocity I am getting while using the same loads as Shortgun is using.
So far I have not found anything with this project or cartridge that has changed my mind about it. I also like the fact that in a pinch I can still shoot factory .30-30 Winchester ammo in it, if for nothing more than fireforming brass.
Considering how much I like this cartridge, IF I insisted on shooting bullets 165grs. and heavier I think the .309 JDJ would be a better choice.
Larry