I haven't got to play with that one; but it looks like a good system. ARMS claims 8.6oz. I believe the standard M4 double heat-shield handguards weigh 8.3oz. Since you can lose the delta ring, you might even gain a few ounces. The older ARMS SIR were a lot heavier (about twice that or more).
I haven't gotten to play with that one; but it looks sharp and if you want both an uninterrupted top rail and rails only where you want them, I think that rail may be your only option. Loctite everything with screws though or it will come loose.
Had no idea the Bushmaster one was so light, and I do like heaver balanced guns.
It isn't that the Bushmaster one is so light as much as it is that after you had optics, bipod, etc. the rifle just naturally gets nose-heavy. A counterweight in the back helps. For a plain, iron sighted M4, the enhanced six-pos telestock is just right.
Any recommendations on a Good 1 in 7 Chrome lined 16" M4 style barrel then? (or should I go for the 20"?)
Bushmaster has them once in a blue moon. I'd ask them about it if you plan to buy from them. If you are looking at other manufacturers, then CMMG, Sabre Defence, Bravo Co., Global Tactical and several others offer a variety of 1:7 barrels. Also, I've had good luck with Armalite 1:9s handling the heavier stuff well.
If you aren't real tied to the M4 barrel and carbine gas system, I'd also consider a light or medium weight midlength 16" barrel from any of the same manufacturers I just listed.
Do you mean the Reflex sight?
And would the TA01NSN-DOC be a better choice then?
Yes, the Docter Optic red dot on top of the ACOG is way up there. It isn't just a slight raise of your head; but a definite cheek weld change. I've gotten use to a tight cheekweld so I found that awkward. The Doc is parallax-free so it doesn't make a practical difference; but I am just not real comfortable about mixing in two different cheekwelds into my training since both irons and scopes require a solid, repeatable cheekweld to be effective. It was one of those things I thought I was really going to like so I was surprised when I finally got to try it and discovered I didn't care for it.
The TA31DOC is better than the TA01NSNDOC in my opinion. The TA01NSN has the partially illuminated amber reticle that disappears in some lighting conditions at dusk and dawn. The TA31DOC has a red illuminated full reticle.
For the "do everything" optic, I really think the TA11 ACOG or 1-4x variables are the way to go. A lot of it is personal preference though. Some people love the Doc-ACOG combo.
