@JC Steel is sponsored by them buy also one of the best shooters around.. Maybe ask him.
I will say this I had a 35mm tube 58mm obj ER25 it really was on par with my S&B -- maybe I was the lucky one but I miss that scope.. Again, I'd ping Jake. I think he might be biased but honest
No, not lucky, I have one but 34mm I'm pretty and not only is it a tank it's also a very nice scope with lots of usable elevation due to the EREK turret. It's bright and super clear. Positive clicks on the turret and they seem to track well. I also have an LR17, their spotter and a 1-8x. All bought in the PX on here for half price. So it was hard for me to go wrong. I can't say anything about the B series other than that they look nice and don't have the slightly complex, yet singular feature that set them apart, the EREK repositionable erector. It's a love/hate relationship at best unless you use +MOA mounts like they were designed for. When it's zero'd, what's not to love? Other than length and weight I guess, they had that going too. But I don't think anyone made a scope as tough as USO did. Again, can't speak for B series other than I'd like a 1.8-10x. USO always had and still does have great magnification ranges IMO too.
Supposedly they use or used Schott glass? Am I correct about that? Made in USA. They can/could be ordered completely custom from tube size to obj. size, erector type, reticle, side or front focus, etc., you name it. So that's nice if you order direct (and if they still do some of that). I think the B series is the answer to people having problems with the EREK, perhaps it was ahead of it's time. It was probably a costly scope to make, the LR's and ER's, etc. So maybe it just didn't work out as planned. IMO, it looks like they were working for a govt. contract that didn't pan out too.
I still like 'em. Didn't plan on being a USO fanboy, they were just great optics for a great price. I paid $2100 for the ER25, all bells and whistles, $1400 maybe for the LR17, all bells and whistles, $600 for 1-8x dual focal plane w/tree reticle, blue illum., and $600 for the observation scope with a custom made rubber eye shutter, all with the milGAP reticle except for the 1-8x that has the simple tree reticle. So for those prices, I can't complain and you can't find a better scope with those features in that price range. Then or now. And as far as I know, nobody else makes a repositionable erector so you can actually use all the 35mils or 110MOA or whatever they advertise. Having matching reticles in two scopes plus the spotter/observation scope is pretty nice too. I like it.
I use the LR17 on an SR25 and the ER25 on an HTI .50BMG. The LR17 is a bit longer and heavier than I'd like on the SR25 but the ER25 matches up with the HTI like it's made for it. No complaints, they're clear and bright and I see way on out with 'em. They're very solid scopes that you can probably pound nails with and recoil hasn't been an issue on the .50. Length and weight are sorta absorbed by the rest of the weapon here so no complaints on that this time.
The dual focal plane 1-8x is really nice in that it works like a ringed dot sight at 1x or so and as mag goes up, the basic tree reticle becomes more visible and the ring just disappears. At higher powers, it's just a FFP tree reticle. I put it on an SBR'd Grendel that I felt could take advantage of something like that. It's 24mm I'm guessing, maybe a bit more? It looks as good as it should given it's size and it's clear downrange. Weight and length on it are negligible given the size. Still solid.
Then they made the massive SN9. A true looooong range scope, one of the first I guess. External adjustments, built in base, up to 40x w/235mm obj. IIRC. I only mention it because they actually made this monstrosity for the very few people that actually needed one. That's pretty cool. I'm guessing they're not as open to stuff like that today though.
Anyway, hard to go wrong on the old stuff, can't say much for the new stuff. But a good deal on a B10 is something I'd be interested in if I can't find a killer deal on a NF of similar range, similar options. And I'd like one of those super compact S&B's. But I'll probably be keeping my USO's either way.