Can you help to identify these frames, bikes or parts?

Does anyone have any tips or tricks for identifying SLX tubing from SL or lower grade tubing? I'm going to check out a frame later and I don't want to trust the decal badge alone. I've read on another forum SLX tubes have rifling (the twisted effect you get in a gun barrel) in them so I should look in the fork steerer tube for it. Is that true? Anyone have some SLX forks they could check on for me? Or any other ways to spot genuine SLX?

Thanks

not sure if the steerer tube would have the rifling.
putting your finger in the bottom bracket and reaching up the seat tube seems to be the accepted method.