At this time both sound really good to me and can not tell the difference at the ear if one is louder than the other. The Deadair Sierra 5 is definitely far gassier than the SF. Despite liking the Keymo mount more, currently not a fan that it is an adapter and would've preferred a sold one piece. At this time I'd suggest the Surefire or a Deadair Sandman over the Sierra 5.
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5.56 RC2 - On a 16" BA Hanson barrel, w/ mid length gas system and a H2 buffer.
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Sierra 5 - On a 14.5 BA Hanson barrel, w/ mid length gas system and a H3 buffer.
