My experience so far though limited as yet is that as soon as you hit 2400 fps, brass starts sticking. Now keep in mind that this is neck sized brass only, and it has not occured with brass that is once fired and necksized. Some cases will go as many as three firings before sticking, but they are the exception, not the rule.
The AI is probably the best way to get greater velocity out of the 30-30, but I am pretty sure that any velocity increase that is over 150 fps is also exceeding SAAMI pressures. Since the AI is not a cartridge covered by SAAMI, that may not matter to you. The Handi will handle far more than the 30-30 can deliver, but as will be seen, faster is best approached another way.
Case life so far has been very good, and I doubt that the brass will fail after 3 or 4 firings because you are raising pressures, even to as much as 50,000 psi, you will just find that case life is shortened.
Last, driving Hornadys SST 150 grainer at 2365 fps from my Handi using BL-C2 equivilent surplus powder, the trajectory is +2 at 100 and -2 at 200, zero at about 170 yards. The velocity is within SAAMI specs, and the pressures are too, BL-C2 will easily do this. 748 will probably come close as will Reloder 15. A simple bullet change gives the 30-30 a 50 yard increase in point blank range in the Handi and is probably equal to an increase in pressure driving those round nose bricks.
There are people who offer pressure testing of ammuntion, but I can only tell you to do a google search to find them, unless someone here has contact info. It would be worth the expense just to know you are not operating with proof quality ammo. I wouldn't be afraid of using new or once fired 30-30 cases at a pressure 50,000 psi, but the rule of thumb is that it takes a 6% increase in pressure to realize a 3% increase in velocity. This means that to realize a 3% increase of velocity over 2350 fps (70.5 fps) a pressure of 35,000 psi must increase 2100 psi to 37,000 psi.
Now carry that to its logical extreme, a 30% increase in pressure to 45,500 psi in theory yeilds 350 fps or an increase to 2670 (assuming a 150 grain bullet and that reality matches theory) This puts you at starting velocities for a 308 driving a 150 grain bullet and in the maximum we would expect from a 303 Brit or 30-40 Krag. Increasing the pressure to 50,000 psi will still leave you inside 308 velocities and never quite equaling them, using 50,000 psi as a ceiling you can only gain another 140 fps or so from the 30-30 case or 2810 fps. We are now approaching max 308 velocities from a 30-30 case and are well into 30-06 velocity territory while the 308 operates at nearly 60,000 psi to get us in this velocity range. Obvioulsy, the math tells us we don't want to go here.
The 30-30 is very good at what it does, being an accurate short range cartridge that is mild in recoil. If you need more than the 30-30 delivers, the logical way to get there is with more gun.
