18inch barrel and sling question for service rifle

[kidthatsirish]

So I have an 18 inch barrel with a mlok rail. The rule book states it must be attached at roughly 13 inches (m-16) or roughly 8 inches (m-4) from the handguard...where does an 18 inch barrel fit in this and does it matter?

[USriflecal30]

What length gas system are you using? Carbine length MAY be used for barrels less than 20 inches. If you have a rifle length gas system then the M16 configuration rule should apply. If you have a carbine length gas system then the M4 configuration should apply. This is in paragraph (c), just above paragraph (e) you took the inches spec from.

[kidthatsirish]

I have a mid-length gas system.

[HighpowerRifleBrony]

Midlength/18" is more proportional to carbine/16" than rifle/20", so I vote carbine location. You'll probably fit carbine length better anyway if under 6' tall.