Firearm safety block devices and methods of use increase the pressured needed to pull back on triggers to cause a firearm to discharge the first shot A block member can be mounted on the firearm at different locations such as above, inside the trigger and behind the trigger. The invention can provide different block members having frangible areas that are broken or bent at selected side imposed pressures. Breaking, shearing or bending the block members is required to operate the firing mechanism as needed to cause the firearm to discharge. A spent frangible block member can be removed and replaced. When the firearm safety block is not applicable the block member can be removed.