Semi-automatic firearm having a safety device preventing conversion to full automatic firing

A semi-automatic firearm having a barrel, an upper receiver, a reciprocating bolt movably mounted inside the upper receiver, a firing pin slidably mounted in the bolt, and a lower receiver having a trigger actuated firing mechanism, wherein the improvement comprises:

• an anti-conversion block fixedly mounted to the lower receiver, said block having a forward section extending into an area behind a hammer operating area of the firing mechanism that does not interfere with the operation of a first type of hammer, but upon replacement of the first type of hammer with a second type of hammer, prevents operation of the second type of hammer by blocking the second type of hammer from full reward movement, and said block having holes that mounting members are fixed into to substantially permanently fixedly mount said block to the lower receiver.

A semi-automatic firearm having a barrel, an upper receiver, a reciprocating bolt movably mounted inside the upper receiver, a firing pin slidably mounted in the bolt, and a lower receiver having a trigger actuated firing mechanism, wherein the improvement comprises:

• an anti-conversion block fixedly mounted to the lower receiver, said block having a bottom section extending into a portion of an area behind a trigger mechanism adapted to prevent replacement of the trigger mechanism with a different type of trigger mechanism, said block having a first notch with a safety switch movably located therein and a second notch connected to the first notch with a portion of the trigger mechanism movably located therein.

A semi-automatic firearm having a barrel, an upper receiver, a reciprocating bolt assembly movably mounted inside the upper receiver, a firing pin slidably mounted in the bolt assembly, and a lower receiver having a trigger actuated firing mechanism, wherein the improvement comprises:

• an anti-conversion block fixedly mounted to the lower receiver by pins that are press fit into holes in said block to permanently mount said block to the lower receiver, said block having a top section extending into the upper receiver and the bolt assembly having an elongate slot for receiving said top section and being movable relative thereto such that upon replacement of said bolt assembly with a different type of bolt assembly not having at least as long an elongate slot, the firearm is unable to operate properly.