I am building an upper with a 16" SS match barrel (M4 profile sans cut), mid gas, and want to know what options are available for a very light weight free float forearm assembly+gas) that will still allow a flip up front sight and a side rail for a small flashlight. If there is a comprehensive weight chart, a pointer would be appreciated.  Options seem to boil down to the following:

#1: Clark carbon fiber (rifle length) cut to mid length (not sure this will work) with a combination gas block, flip up front sight and flashlight rail. I think this will be in the 10oz range (complete forend, gas block, front sight, and rail), but I wonder whether there will be problems with the carbon fiber forend or other problems I have not considered and I am not sure I can cutoff the carbon fiber forend cleanly.

#2: JP enterprise alum mid length forend with modular rails. I think with gas block and flip up front and a rail for the light this would run 19oz or so.

#3: YHM has a mid length FF with modual rails, but I can't locate any weight information.

#4: what other options should I consider.

thanks in advance

I am in the same boat, with pretty much an identical build in mind.  If anyone can shed light on how the upper balances on the lower as well that would be fantastic.  Mine will have a CTR stock on the lower and its primary use will be plinking/practice and it will be used as a coyote calling rifle as well.

Thanks!

You can cut the Clark carbon tube, just use an EXTREMELY fine toothed saw. Like, the finest hacksaw blade you can get. Then just sand off the cut end. Potentially I would cut the rear end off so you still have a nice factory edge on the front. I haven't tried it though, so double check before you cut.

I actually use the JP V-Tac on all my builds. I have 1 rifle length tube on a 14.9" middy, 1 rifle tube on an 18" rifle gas with the PRI flip up gas block (the only one worth using IMO), and, in progress, a 16" 6.8 middy with a middy V-tac and a PRI gas block.

I like the Barrel nut system on the V-tac, but if I were going for super light I would use the Clark tube.

They actually have several.  The lightweight models are listed on the following company product info page, with weight info for each (the mid-length model, which I have, is listed as 12.4 oz.):

http://www.yankeehillmachine.com/store/forearms.html

Daniel Defense OMEGA rail.

9.7 ounces.

$289.00

Easy to install. Uses standard delta ring. No gunsmithing required. Free Floats. Extremely light weight. Rock Solid.

/thread

thanks. Cutting the clark to mid length and using a Young Front Sight gas block (that appears to have a tiny rail allowing a light to be added once in a while on top) would result in under 10oz for both. (Anyone have experience with the young system?)

The V-TAC looks like a great system, but at 13oz plus gas block and sight, we are talking about roughly 1/2 lb more weight.