Complex sentence: The R5, when compared to the larger R4, has a shorter barrel, gas system and handguard, it lacks a bipod and the flash hider does not support rifle grenades.
Split into simpler sentences: The R5, when compared to the larger R4, has a barrel that is shorter, together with a shorter gas system and handguard. It also lacks a bipod and the flash hider does not support rifle grenades.