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I hope this is not off your subject too far.I wounder why 1in 7 twist not 1 in 9 twist on barrel.Are you shooting full auto on your upper?If not you might have better accuracy with 1in 9 twist 16"M4 profile barrel by using common 55 gr or 62 gr bullet.
For 1 in 7 barrel,since you already have Spike lower,Spiker upper might be a better choice as far as color match plus the customer service is excellent at Spike.