You're dead-on in the assesment that the SR556 is "nose-heavy".
I have the 556c and I really like it. even though the weight difference doesn't sound like much, it makes a difference in how the gun handles.
anyone tried to take the quad rail off? I've been thinking of sending my barrel to ADCO to get lightened and shortened.
I have one too, i would agree with everything you posted, except mine does have play between the uppen and lower. I went with the Magpul ACS stock and kept the stock grip. I like the factory flash hinder, it reminds me of the M14 .
I am also running and Eotech one mine (517) plus a tango down VFG but will be swaping out to a Magpul VGF (is on the mail). Yes it is heavy, especially up front. I wanted to send mine to get cut to 14.5 but the barrel etching would be ruined. I have a little wear on the tube but nothing serious. From what i have read it will kind of stop after a 1k rounds or so. I still have to replace the bolt pin to a round one, because it has marred my upper a bit.
Does anyone know how to keep spare AA batteries on the Magpul ACS from rattleting(sp).
AFAIK the rails are pinned in place and can not be removed by the end user.