While 9x19 is not my usual preferred cartridge for primary carry, I've been known to carry 115, 124, 127 and 147gr. loads in different 9mm pistols. Most often, if I'm carrying a 9x19 as primary, it is loaded with either 127gr. WW RA9TA +P+, 124gr. +P Gold Dots, or 115gr. Cor-Bon +P JHPs. I'm confident in expansion and penetration capabilities of all three loads, and feel adequately served by any of them. I know very knowledgeable folks who like 147gr. 9mm loads, but I prefer the lighter bullets. Insufficient penetration just is not likely to be a problem with very many factory 9x19 loadings these days. Overpenetration, however, can be an issue, especially with ball. I'm told that the latest generation of 147gr. WW Ranger ammo is performing well in the field, unlike much of the earlier 147gr. loads, which were iffy on expansion. I'm hearing good things about 147gr. +P Gold Dots, too.

One other factor worth mentioning is point of impact of various bullet weights. While not as extreme as in revolvers, even in autoloaders, heavier bullets will strike higher than lighter ones. Typically, fixed-sighted 9mm pistols will hit near POA with 124 gr. bullets, with 147s hitting higher and 115s hitting lower. This is due to recoil occurring during the bullet's travel down the barrel, with more muzzle rise occurring with heavier, slower bullets, raising POI.