This email is in response to the R.I.P. bullet paragraph seen on your blog. It is, as you suspected, limited in performance due to the nature of its design. I imagine the developers of the RIP theorized they could take the principles of bullet fragmentation (effectively demonstrated from 5.56mm ball ammo within certain distances) and apply them to a pistol caliber. The lethal effectiveness of bullet fragmentation relies heavily on its velocity upon impact. Since pistol rounds don’t travel nearly as fast as a rifle round, they depend on the summation of bullet mass, rather than speed, to deliver terminal energy.
In short, you want all 124gns of 9mm to terminally dump its energy within a target without over penetration, hence the FBI 12″ rule. The RIP bullet, however novel, is essentially a 50gn slug after the initial impact. It’s shards would be traveling too slow to cause any real damage, unless by chance it severed an artery or a critical nerve. – D.R.