Harry O and targetguy: I've never had a problem with 9mm cast loads tumbling, but I've never cast out my own 9mm bullets, either. I have just purchased pre-cast slugs in the 125 gn rn configuration and shot them with different Unique powder charges from the old Lyman manuals and they all seem to have shot fine from: a 9mm Luger, a 9mm P-38, and 3 different 9mm Tokarevs.
But, the 9mm has a 1:10 twist and has a history of not stabalizing cast bullets well. Of course, if you take the same bullets and load them into 38 Spl cases and fire them down a S&Ws 1:18-3/4 twist they probably stabalize a lot better.
Harry - when you described the results of your testing, you mentioned the softer bullets sized at .356 tumbled all the time, the harder ones cast at .358 tumbled about 25% of the time. Have you tested the harder ones at .356 diameter - I'm thinking those are closer to bore size than oversize and harder like a jacketed bullet and may shoot - maybe not....
The 9mm was never designed around a cast slug - the 38s/357s were and the slower twist reflects that application. The faster twist of the 9mm may only like jackets or hard cast bullets.
My old Lyman manual lists 3.5 gns of Bullseye with Lyman's 356402 - 121 gn slug, which is truncated, as an accuracy load for that bullet. 4.4-4.5 gns of Unique should put you in the same ballpark. With the 158 gn 358311 bullet (roundnose) the accuracy load listed is 3 gns of Bullseye for 869'/sec. I used to use 3.5 gns of Unique under this bullet for subsonic loads at the same velocity and didn't see any tumbling. HTH. Mikey.
