Ruger P-89's have a big top end on them, and you might want to try shooting +P rated 9mm ammo out of it, or something zippy like NATO grade fmj. The big Ruger P-series autos are happiest when feed normal powered 9mm ammo, and a lot of the under-loaded 147-grain sub-sonic loads don't have the recoil "oomph" to reliably cycle the slide, especially if you're moving while you shoot or somehow limp-wristing. Winchester used to put a warning on their LE ammo boxes stating that the sluggish 147-grain loads might not reliably cycle all 9mm pistols.
Any of the "premium" jhp loads like Gold Dot, Golden Saber, HST, etc., have been engineered to pass the FBI's excellent (and nowadays industry standard) series of "barrier" tests. So they'll do about as much as can be expected from a handgun bullet. In the end though, even "premium" jhp defensive ammo isn't as important as the skill of the defensive shooter...so even if you're carrying Wal-Mart's "Winchester White Box" jhp's you'll be fine as long as you get good hits on the target. The grain-weight of various loads within a given caliber aren't nearly so important as finding a load that cycles as close to 100% reliable in your handgun as you can make it.
