I'm currently setting up my SCAR 17 as a DMR.  Rifle weight with atlas bipod and all mods I want is like 9lb 5oz minus scope and mount.  Currently it holds my Kahles K16i in a Delta mount until my MDR arrives.  I'm looking at the Nightforce 2.5-10x42 and the U.S. Optics B-10 1.8-10x scopes figuring 10x is a good enough top end, even after I eventually put a match 20" barrel on the rifle.  I had looked at the Trijicon 1-8x but decided against it due to the lack of a parallax adjustment knob (and I really, really like these other 2).  

Anyone use the 1.8-10x? I like the idea of the lower bottom end, but wonder if it is worth caring about.  And if it is, is it worth the extra half pound weight? My door kicking days are done, and since this will almost always be shot off a rest (tripod, bag, bipod, etc), I think I'm OK with the extra weight especially if I plan on the 20" barrel upgrade down the road. I mean, yeah it's still a half pound extra to carry but if it's a dedicated DMR role then it shouldn't be as big a deal.

If the lower end difference isn't worth it, the NF has everything I want from a non 1x scope.  

So aside from specs, anyone have experience with both?  What are your thoughts on them for this setup?

But damn, if someone makes a reasonable 1-10x that runs fine on a SCAR 17, let me know!

I haven't used a US Optics 1.8-10, but I have the NightForce 2.5-10.  The 2.5-10 NF is top notch.  The one I used was one of the non-illuminated, but now they come both ways.  I felt the 2.5 was plenty low enough magnification for close in shots.  I was hammering steel at close range with no follow-up shot problems at 2.5 with a 5.56.  The 10x felt like just enough at longer ranges.

Hope that helps.

It does. heh

Given the range of the rifle, and magnification level optics your looking into you don't need adjustable parallax. Actually you'd probably be better off without it one, less things to have to adjust.

Going out to 600 to 700 yds you don't need 10x magnification.   In the 400yd to 600yd range 8x is fine.  You don't need 10x until you are 800yds+ and that is the outer limit with a semi 7.62 gun.

I got back from a 5-day "Combat Rifle" class at Gunsite a few weeks ago.  Essentially a DMR class for 7.62 guns.  Great Class.  There were 9 students in the class and 7 (including myself) were running SCAR 17's.  One guy had a JP Enterprises .308 and the other was running some other AR-10 type rifle.

For the glass - a few of the guys were running Leupold 1.1-8x scopes, I was running a Bushnell 1-8.5x, one guy had a Trijicon VCOG 1-6x.  There was only one guy with a scope that didn't go down to ~1x.  He was running a 3-9x Leupold.  One instructor was running a Leupold D-EVO (6x) with an Aimpoint T-2 micro.

About half the class was short range (15 yds to 50 yds) and the other half of the class was long range (~250yds to ~800yds).  Most of the long range was 300yds to 550yds and we did a little bit at 600yds to 800yds.  Even at 800yds the 8.0x to 8.5x was absolutely fine.  The guy with the VCOG actually did fine out to 600yds as well.

If you are ever shooting under 75 yds being able to go down to 1x is a blessing.  For me, I think being able to go down to 1x trumps the bit of extra magnification on the upper end (8x or 8.5x vs 10x).

USO 1.8-10x MR10 is flat amazing. I much prefer it to the smaller optics. Much more flexible. I would say screw it and just use a fixed 10x ST-10 if there's no need for shooting closer than 75yrds. FWIW, I have a buddy selling my old ST-10. You could probably pick it up for a song. MPR mil reticle, EREK, non-illum.

A lot depends on the type of shooting you will be doing.

What type of targets are you going to be shooting at? Will they be moving? Do you hold or dial for wind?

If you will be shooting movers, especially faster movers; 10x will be too much magnification. Of course you can dial down but on a SFP scope, holding the lead is not as straightforward.

I've taken shots at 1/2 and even 1/4 MOA targets at 500yards+(I don't hit every time, but I do get hits) with my DMR. 10x mag may not be enough to see your target depending on what type of target your shooting at.

If you will only be shooting at 10x then either of the options will work. But really I'd need more information on the type of shooting you do before I can recommend one scope over another.