A friend of mine saw a gun at the store that was labeled as the "most quiet gun". Is this correct English or is it more correct to say, the "quietest gun"?
Short Answer: "quietest" sounds better to me, but both are grammatically correct
Long Answer: For comparatives and superlative(
-est, respectively) forms of words, alwaysuse "most" for words with words for three or more syllables. For words with one syllable, always use "-est." Two syllable words can vary, some with only one correct comparative/superlative and some where both are acceptable. Quiet is a word where both forms are acceptable.
Since quiet is a two-syllable adjetive, the rule-of-thumb would make more quiet and most quiet the expected comparative forms; however, quietest and quieter are six-times more common (or, as many would say, "commoner." Both forms are correct, but the single-word construction is what the American ear expects to hear.