Complex sentence: The M829 has a ballistic cap and five tail fins made of aluminum; it also has a long carbon fiber sabot, which holds the sub-caliber round in place in the barrel, that breaks off into five "petals" as the round leaves the gun tube.
Split into simpler sentences: The M829 has a ballistic cap and five tail fins made of aluminum; it also has a long carbon fiber sabot. The sabot holds the sub-caliber round in place in the barrel and breaks off into five "petals" as the round leaves the gun tube.