The more precise the fit, the less chance that the Glock 30s will fit. Obviously, since it is thinner overall than a Glock 30, the 30s will fit in most Glock 30 holsters. However, I have not found this to be true with Glock 19/23 holsters. The Glock 30s will fit in some, but not all Glock 19/23 holsters. Obviously, leather will stretch a bit, but I have no interest in stretching out my Glock 19/23 holsters. However, I am comfortable putting my Glock 30s in my Mitch Rosen ARG which was made for my Glock 30 because the gun is thinner. Rather than make due, I simply went ahead and ordered a Raven Concealment Phantom holster for the Glock 30s and it fits perfect, like a glove. The 30s was a bit tight in my 19/23 Phantom and a bit loose in my 30 Phantom, by the way.