Original sentence: A 3-prong flash hider and newly-designed ventilated handguards were also used.As with the rest of the 550 family, it uses a modified SG 540-type action, itself based on the AK-47, providing similar reliability and resistance to fouling to those parent weapons.Compared to the SG 550, the SG 552 features a 226 mm barrel with shortened gas tube and piston, the return spring was relocated behind the bolt carrier group, inside the receiver and is guided by a rod that rests at rear of the receiver housing similar to an AK-47.The SG 552 LB incorporates a longer barrel designed to fire rifle grenades and mount a bayonet.This firearm is used by police/military forces around the world and is available to civilians in some areas
Edited sentence: A long barrel version of the SG 552 designed to fire rifle grenades and mount a bayonet, known as the SG 552 LB, is also available.As with the rest of the 550 family, it uses a modified SG 540-type action, which itself is based on the AK-47, giving the rifle extreme reliability and a high resistance to fouling.Aside from that, a screwed 3-prong flash hider and special, ventilated handguards were also used.Compared to the SG 550, the SG 552 features a 226 mm barrel with shortened gas tube and piston, the return spring was relocated behind the bolt carrier group, inside the receiver and is guided by a steel (polymer in newer production models) rod that rests at rear of the receiver housing (design similar to an AK).SG 510.SG 540.SG 550.The shorter piston was also integrated into the bolt carrier group.This firearm is used by police/military forces around the world and by a limited number of civilians