CREATE TABLE table_17834 ("Colt model no." TEXT, "Name" TEXT, "Stock" TEXT, "Fire control" TEXT, "Rear sight" TEXT, "Forward assist" TEXT, "Barrel length" TEXT, "Barrel profile" TEXT, "Barrel twist" TEXT, "Hand guards" TEXT, "Bayonet Lug" TEXT, "Muzzle device" TEXT)

What is the barrell profile that goes with the gas piston carbine?
SELECT "Barrel profile" FROM table_17834 WHERE "Name" = 'Gas Piston Carbine'
SELECT "Barrel profile" FROM "table_17834" WHERE "Name" = 'Gas Piston Carbine'