I have revised some of my thinking on maximum loads for the .30-30 improved and thought I would share them.
I have been shooting a 20" Winchester M-94 B. B. in .307 and two 20" .30-30 Improved rifles side by side for several weeks now and have reached some new conclusions. I have previously said that with Hodgdon BLc2, 335 and 4895 along with Winchester 748; we can safely achieve 3000 fps with the 110-grain bullets, 2700 fps with the 125/130-grain bullets, 2500 fps with the 150-grain bullets and 2300 fps with the 170 grains bullets. I believe these statements are still valid for the Winchester M-94AE and the Marlin 336 with 20" barrel.
I have suggested that with Hodgdon Varget and Alliant Reloader 15 that 2400-fps with the 170-grain bullets was safely attainable. I no longer feel this is true.
I have been shooting the Speer 170 grain JFN bullet in the 20" Marlin 336 and Winchester M-94AE at 2400 fps using Hodgdon Varget and Alliant Reloader 15. I have had no problems with extraction, case life or any other signs of excessive pressure in either rifle with these loads. By comparing velocities between the .307 (using published load data that has pressure information) with our .30-30 Improved results it has become obvious that our loads are exceeding 50,000 CUP by a considerable margin. Some of our .30-30 Improved loads have generated velocities that exceed those obtained in the .307 utilizing maximum published loads for that caliber.
All of our previous .30-30 Improved load data has been used in several different rifles in hot weather without difficulty. We have used Varget and RL 15 only in cold weather and will not repeat any of our "higher velocity" tests in hot weather. A 170-grain bullet at 2300 fps from a 20" barrel is a considerable increase compared to real world velocities we have chronographed using the standard .30-30 in lever action rifles. I have killed quite a number of deer with the .307 and a 170-grain bullet at 2350 fps. This is a killing combination.
The results we have obtained certainly validate the cartridge case shape theories of P. O. Ackley. His straight wall, sharp shouldered case appears to be able to withstand much higher pressure than I care to regularly work at, without any outward sign of distress. I have obtained a real Improvement with good accuracy and see no reason to tempt fate. 2300 fps with the 170-grain bullet is plenty for me.

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slim