98 until it engages the appropriate tooth 98 associated with the pawl arm 54 being in the upward or ready position the spring 188 connected to pawl 122 tends to assure that the tooth engaging portion 130 is always in contact with the ratchet wheel 90 so that the tooth engaging portion 130 is ready to engage the tooth 98 after another round has been fired as best shown in fig1 the bolt 202 has been rearwardly displaced with the effect that the pawl arm 54 rotates on pin 66 and another shot has been counted it should be noted that the trip pawl 100 has contacted the rearward arm 178 of selector blade 170 and has tripped the selector blade 170 from the burst fire configuration to the semi automatic configuration it should also be noted that the trip pawl 100 rotates past the rearward arm extension 178 in order to prevent binding with the rearward arm 178 after the selector blade 170 has been pivoted to the semi automatic firing configuration then the disconnector sear 157 engages the disconnector notch 146 with the result that the trigger must be squeezed for each and every shot subsequent to entering the semi automatic firing configuration burst firing may be reinstated by resetting the selector blade 170 to burst firing configuration by releasing the trigger and resuming the setting of fig1 the trip pawl 100 has been disclosed as having two outwardly extending arm extensions 110 and.