Re: Noveske 16" Recce SB and DD MK18 rail???
A couple of points to mention on the Noveske SB : the upper part of the Noveske SB is quite a bit higher (around .75" above the top of the barrel) and fatter (around 20/32" excluding the switch detent on the front portion) than a Lo Pro GB. The integral gas tube on the Noveske runs parallel to the length barrel (around 1/2" above the barrel) rather than starting low and having an upwards bend a couple of inches out from the receiver gas port.
The DD RIS II is 9.55" long and has an internal diameter of only 1.15" so you're not going to fit the rear 1/2" of the Noveske under the rail.
I like the pic that salmonaxe posted of the Mk18 with the cut-out RIS - very neat. But it looks like a carbine length gas system and not everyone is going to want to go down the route of cutting up their nice new RIS....
If you don't want to cut the top of your RIS II or you're using a mid-length gas system, why not look at using the Syrac Ordnance Lo Pro Adj GB?
Only possible issue I would see on that is, depending on the diameter of any muzzle device you use (such as the 51T Blackout in the pic) and length of gas system adjusting the Syrac could be a little tricky as you need to access both the hex bolt adjuster and release.
But...as you're using a 16" barrel with a mid-length gas system and not going for an SBR...that is likely not even on the radar for your build.
It may not be quite as "elegant" in operation as the Noveske but the rear 1/2" of the Syrac should fit under the 0.55" extended length of the DD RIS II and you'll get unimpeded access to the adjustment.
Or. as another alternative...look at getting a custom adjustable block made to your specs by Paladin Machine Service?
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2230690&gonew=1#UNREAD
