Bore diameter tells you almost nothing about whether a cartridge will run in a given gun. The base of the case does. This set splits cleanly down the middle, with one bottleneck and one +P round adding a wrinkle each.

Sorting by that one feature takes a minute.

Rimmed, for a revolver

38 special ammo, .357 ammo, 44 special ammunition and 44 mag rem are the four rimmed revolver rounds here, two parents and two magnums. The brand lines follow their cartridge: hornady 38 special and 38 wadcutters are rimmed .38 Special loads and feed exactly like any other .38 Special, because that is what they are.

Rimless, for a magazine

380 auto ammo, caliber 40sw and 38 super cartridge are rimless straight-walled autoloader rounds. They headspace on the case mouth and stack cleanly in a box magazine; none will headspace in a revolver cylinder without moon clips or a dedicated design.

The one bottleneck

.357 sig ammo is rimless too, but bottlenecked — a .40-caliber case body stepping down to a 9mm bullet. That shoulder is what lets it reach its velocity and also what makes it feed unusually reliably; it is the only bottleneck on this shelf.

Why the look-alikes fail

The dangerous confusions here are length confusions, not rim confusions: a magnum forced toward a Special's cylinder, or a +P round into a pistol built for its parent. The rim tells you revolver or pistol; the case length and the gun's own stamp tell you which one.

Never substitute a similarly-named cartridge without confirming case length, rim design and pressure rating against your firearm's chamber markings or owner's manual, and verify current stock and any state shipping restrictions before ordering.