At work (with like 800 different firearms) I've been quietly testing this stuff... the worst of the AR-15's. The gnarliest of the shotguns. The raggedest of the revolvers... even a Glock. Funny thing... with the Glock you don't think it really did that much... until you feel the other Glocks. Then you realize that you are not hearing the same noises and feeling any grit... it's just... smoother. And the old used Taurus I put Slipstream it... it went out the door today. Gone. "Hey, this is pretty nice." Sold. There is a pattern here.
The AR's I put it in... some didn't feel much improved at first. But you keep cycling the action... letting that stuff work in... and all the sudden you realize that it's almost like it's a different gun. A better gun.