Yes, FLINTLOCKS is a Scrabble word!

Letter values in Scrabble US: F 4, L 1, I 1, N 1, T 1, L 1, O 1, C 3, K 5, S 1.

Is it a valid word?

FLINTLOCKS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a muzzle loader that had a flintlock type of gunlock
an obsolete gunlock that has flint embedded in the hammer; the flint makes a spark that ignites the charge