Firearm assembly having a locking block and slide

A firearm assembly configured to provide changing of a barrel of a firearm wherein the barrel could be of an alternate caliber comprising:

• a receiver, said receiver having an interior volume, said receiver having a bottom, said receiver having an inner rear wall;
• a locking block, said locking block being configured to be disposed within said interior volume of said receiver, said locking block having an upper surface and a lower surface, said upper surface of said locking block having a front rise member and a rear rise member extending upward therefrom, said upper surface of said locking block further including a valley, said valley being intermediate said front rise member and said rear rise member, said locking block further including a rear edge wall;
• a barrel, said barrel having a first end and a second end, said barrel configured to discharge a round of ammunition at said second end thereof, said barrel having a first portion and a second portion, said first portion and said second portion being integrally formed, said second portion of said barrel being proximate said first end thereof, said second portion of said barrel having a lower portion, said lower portion of said second portion of said barrel having a lower rear wall, wherein said lower portion of said second portion of said barrel includes a front shoulder member and a rear shoulder member, said rear shoulder having a lower rear wall, said front shoulder member and said rear shoulder member extending downward from said lower portion and wherein said rear edge wall of said locking block being axially aligned with the lower rear wall of the rear shoulder of the second portion of the rear end of the barrel;
• and
• wherein the locking block and the second portion of the barrel are mateably coupled so as to facilitate an operable connection intermediate thereto.