I am in a similar situation as you and building a lightweight 6.5 Grendel. Long story short I need a light rifle and my match gun is too heavy, 15lbs, and my .223 doesn’t meet the requirements. I have looked at going with carbon fiber stock and barrel for my matchbox rifle but that only shaves 4lbs from my match rifle, I really want to be in the 8-9 range fully equipped. Hence, I started looking at the 6.5 Grendel.
Right now my build with the NF2.5-10x24 specs out at 7.9lbs. This is overly conservative as I think it’ll be more in the 7-7.5lb range. I am just using the NF 24 because it is a donor scope from my MK12 for the time being.
So onto scopes, I need to be able to engage targets out to 1000yrds and the scope needs to be bombproof, but I also want it to be lightweight in keeping with the trend of the build.
Personally, I think it is a fools errand to build this lightweight rifle and then throw ~2lbs on tops of it (25oz scope + mount) unless you are getting something significant in return for the extra weight. Staying with your budget and magnification I would go with the SWFA 3-15x42 as it is the only one that meets the criteria. If you can loose some mag on the high end than look at the Burris XTRII 2-10 and Sig Sauer Tango 4 3-12. Obviously I would put these in a lightweight 3.5oz AeroPrecision Mount.
If you can be patient, I know it is hard to do and I have trouble with it, I would try and save some coin and can’t see if you can move into a Mark6, T5Xi, or ATACR F1. Yes, it adds and additional 6oz for the T5Xi and ATACR, but I think you will be satisfied with the upgrade in glass. I would not go above the 24-25oz weight unless I knew I was getting a major upgrade in the glass department. So if you have to stay on budget and magnification go with the SWFA. I have seen a handful of Mark6 in the PX around the $1500-1800 range. ATACR F1s had a slew of them in there a while back right at 2k but they have dried up recently and the T5Xi can be found at $1300-1500.
Lightweight (<25oz)
Leupold Mark 6 3-18x42 24oz ($2200 New, $1600-1800 used)
SWFA 3-15x42 24oz ($700 New, $600 used)
Nightforcs NXS 2.5-10x24 17oz ($1500 used)
Burris XTRII 2-10x42 23oz ($800 New)
Sig Sauer Tango 4 3-12x42 24oz ($750-800 New)
Heavier (>25oz)
Nightforce ATACR F1 4-16x42 30oz ($2500 New, $2000 used)
Steiner T5Xi 3-15x50 30oz ($2000 New, $1200-1300 used)
Bushnell DMRII 3.5-21x50 34oz ($1500 New, $1300 used)
Bushnell LRTSi 4.5-18x44 27oz ($1500 New)
Bushnell LRTSi 3-12 28oz ($1300 used)
Burris XTRII 3-15x50 31oz ($890 New, $750 used)
Vortex Viper PST GENII 2-10x32 26oz ($950)
Vortex Viper PST GENII 3-15x44 28oz ($1000)
Nightforce NXS 3.5-15x50 30oz ($1800 New, $1500 used)
Nightforce SHV F1 4-14x50 30oz ($1250 New, $1000used)
Athlon ARES BTR 2.5-15x50 27oz ($800 New)
Sig Sauer Tango 6 4-16x44 26oz ($900-1000 New)
All this info came from SWFA, Sport Optics, Midway, and the PX Section
A couple of notes: I have tested the 2-10x42 version of XTR II and liked that scope very much. G2B reticle is sorta simple by modern standards, but it works exceedingly well and I have a lot of mileage with it.
Generally, if you are OK with previous generation scope, I keep on seeing 1st gen Sig Tango 6 scopes on a significant discount. I tested the 3-18x44 (
http://opticsthoughts.com/?p=1748 ) and liked it. I have seen both 2-12x40 and 3-18x44 models recently in the $800-$1k range and at those prices they are an exceptional deal.
Fundamentally though, since there are several options available, you should think about the reticle that works for you and whether you want to primarily use the reticle for wind and trajectory compensation or whether you plan to spin the turrets a lot. Both are viable approaches, but they will drive the reticle choice, which, in turn will drive the scope choice.
I am sorta comfortable with both approaches, so comparatively simple reticle like G2B and Mil-Quad really work well for me. However, my favourite scope has a somewhat simple version of a Christmas tree reticle (Gen 2XR in Tangent Theta TT315M).
If having a reticle that allows easy wind holds at distance is important, then you should be exploring designs like Vortex' EBR-2C in the Gen 2 PST (I should have the 3-15x44 and 5-25x50 Gen 2s in my hands next week).
Similarly, Athlon Ares has a pretty modern reticle and is worth a look.
Now, my original opinion remains and for the money, SWFA 3-15x42FFP is not yet matched by anything I have seen.... as long as you can live with the reticle and lack of illumination.
Lastly, while this scope does not get as much attention here as it should, my 8lbs Grendel most of the time has a SWFA SSHD 3-9x42 scope on it and I like it immensely. It is a simple, but well executed scope. As it happens, it site in a Aero Precisoin mount because I was curious about how well they do. I bought several of these mounts on sale and proceeded to be rather disappointed with every single one of them. I made them work, but on all of the ones I have, the rings are out of round and with some scopes, they will squeeze the tube in ways that hurt the scope's internals (for what its worth, the 3-9x42 SS seems to work just fine in that mount even when I tested it on a 458 SOCOM).
ILya