I have two Sorties and a Barrage that would not fire in semiautomatic mode. On firing the bolt would retract enough to cock the hammer but not far enough backward to clear the magazine rotor. The solution was how to get the bolt to retract far enough backward to clear the magazine rotor and allow it to rotate. These guns are blowback and the bolt movement to the rear is caused only by the air used to fire the pellet. On its backward movement the bolt must compress the hammer spring and the reloading spring at the muzzle. To increase the rearward pressure on the bolt I used heavy pellets. To reduce the force needed to compress the two springs I reduced their tension by 6 turns counterclockwise on the muzzle reloading spring and by using only 6 turns counterclockwise on the hammer spring. I further reduced the force needed to move the bolt backward by removing the grease in the reloading gear box and replacing it with a light oil. Now the bolt retracts completely on firing and all three guns fire semiautomatically without a misfire.