Need a little more context maybe for a better understanding but this is what is in the Ky hunting guide as a definition: Modern gun (breech-loading firearm): a rifle, handgun, or shotgun that is loaded from the rear of the barrel. It also states elsewhere that "modern firearms include centerfire rifle or pistol or shotgun used with slugs."
My Glock 17 from my modest collection is my favorite now - very controllable and accurate even in rapid-fire. And some emotional aspect - its design! It is my personal feeling that a Glock has all of the warmth, charm, personality and character of an industrial tool.