The compressed powdered metal frangible bullets are the defacto standard for training on steel at close ranges and in shoot houses to reduce some of the hazards of ricochet, damage to steel plates, and penetration of some materials (mostly thick plate steel and concrete). I've used them for that purpose, but not for carry. However, I am beginning to be curious about compressed-powdered frangible's ability to transfer energy and still penetrate. I think most people's impression of frangible ammo is the concept of bullets that won't overpenetrate, but just powderize upon impact. For anything other than training, people consider frangible to avoid overpenetration or with the hope that they won't penetrate barriers and cause collateral damage. This is not how the work at all in my experience. Sinterfire bullets penetrate quite well. They will shoot through many materials like dry-wall, wood, plywood, automobile body panels, and plate glass mostly intact and remain very much a hazard on the other side. In fact, I would say they penetrate about the same as hollowpoints. The big difference is how they behave on the materials that will stop both frangible and hollowpoints. Whereas hollowpoints will break into large chunks or bounce intact, frangibles will powderize on those barriers. So what about ballistics gel? I've seen several tests where Sinterfire frangibles designed for the purpose will penetrate a multi-layer clothing barrier and then penetrate the gel to 16". They also fragment and shed weight substantially, which results in energy transfer and wounding, but with still enough weight retention to achieve that penetration. This is fairly remarkable. I already knew that people who thought frangibles would be stopped by drywall were wrong. But hollowpoints remain the overwhelming choice for carry because frangibles are generally regarded as lacking penetration. Is that wrong also? Take a look at the results of this gel test for .38 Special -- a weak cartridge where many people recognize that you can have penetration or expansion, but usually not both. Note also the test used a S&W 640 J frame (short barrel) https://www.ammunitiontogo.com/prod...fire-special-duty-110-grain-frangible-hp-ammo Then take a look at these tests on drywall+gel, plywood+gel, denim+gel and more: http://sinterfire.com/media/videos/ I also want to mention DRT: http://www.drtammo.com They also make bullets with a powdered metal core, but instead of sintering them, the insert them in a copper jacket with a hollowpoint. They offer some rifle bullets that could be interesting for hunting. I wasn't able to find as many videos of their product tested or demonstrated. With the type of results demonstrated above, why do these bullets continue to be used pretty much exclusively on steel?