You have to consider the gun from which it’s fired – primarily its barrel length. Barrel length determines velocity and velocity impacts penetration and expansion in a big way. You have to consider the caliber because Bad Dood Blaster Xtryllium might be great in 9mm but stink in .380 ACP. You have to consider the bullet weight because that’s an essential factor that influences the delicate balance of penetration versus expansion. In other words, Brand X’s 147-grain load fired from a 4-inch barrel Power Pistol Company semi-automatic might work just fine, but when fired from an ACME Pocket Master with a 3-inch barrel, it might fail to expand as designed.
If you want to know if a particular ammo choice is right for you, then you need to test a specific brand , a specific bullet weight, and you need to do that from your gun. Using gelatin blocks is the industry standard, but if you don’t want to invest time, energy, and money in all that laboratory work, you can do the budget method. Just collect a large pile of old newspaper, immerse it in water for a day or so, and use that as a budget gel block. While the FBI ballisticians won’t accept those results, it will give you an idea of how your ammo performs. Be sure to place some fabric layers in front of your soggy pile of fake news.
With all of the previous disclaimers said, there are a few loads in the 9mm category that have stood out and demonstrated excellent performance through a variety of pistol types in our gelatin testing over the years. I should note that all expansion and penetration numbers shown below were all taken in a “heavy fabric” test where the bullet had to penetrate four layers of light, medium, insulation, and denim before impacting the gel blocks. Any bullet will expand in bare gelatin, but many fail when encountering tougher clothing barriers first. All that clothing tends to clog up hollow points and make picture-perfect expansion more elusive.