It sounds like you're not attaching them properly. I did a quick Google search and found this. It's easier for you to reference the pdf than me try to explain it through text. Scroll to page 13 of the attached pdf link.
http://www.atu.edu/rotc/docs/14_MOLLE_Usecare_1_.pdf
I just weighed my 18" (including brake) with a PRS, no mag, atlas bipods and an empty scope mount and it weighed 11.8. That's as close I can get to a 20" because that's what I have. Hope it gives you a good ballpark idea.
I have a GAP-10 being built right now. 18" finished length barrel including the Surefire brake. It should be pretty handy and shoot out to 800 with no problem.
For most practical use the 1600 is the way to go. I haven't had any trouble out of mine. It's small which makes it easy to carry and it ranges really fast. To the human eye it almost appears instantaneous.
Just as the title says, what is it that you're waiting on to be made/shipped. I'll be happy when my ________ finally gets here.
I'll start.
GAP-10, KAC SR-15E3 IWS Carbine SBR, and Surefire SOCOM762-MINI.
I'll be happy...one day.
Well cutting your base in half wasn't the best idea. It looks like your power adjustment ring is sitting on the base. That would cause you to lose all your elevation.
Re: Paint barrel or not?
Rattle can it. If you don't like it strip it back off. No harm no foul. If you do like it, strip it back off and have it Cerakoted that color.
Re: trigger for 6.5 Grendel
The SD-3G in 3.5 pounds is really light. Almost scary light. I found that I could run the 5lb one more effectively than the 3.5 bc the return spring is so light on the 3.5. They're nice though. Really smooth. However, the SD-3G wasn't designed for a precision...
Re: Kriss Vector
The Kriss Vector is a piece of junk. It's a terrible design that malfunctions constantly. I work at a range where we have one to rent. Very seldom does a customer get through a box of ammo without having some kind of problem with it.