Tag Archives: 5-25

The US Optics Foundation 25X

Many years ago, when I first stumbled down this rifled rabbit hole, I would daydream about the high-end and prestigious rifles I saw in magazines and movies. The internet had not yet become the superhighway it was destined to be, but as it developed I could also visit websites and court those beautiful works of art. Not only was it the rifles, but the impressive optical sights that accompanied them. My dreams of owning such a piece of artisanship seemed unattainable at the time, but I never could have foreseen just how far down this hole I would go.

Years would pass, more than a decade, and I found myself the proud owner of what I had always considered a dream scope. US Optics had always been one of the brands I was smitten with, maybe it was the incredibly robust design that seemed overbuilt for what many would consider standard use. On top of their strength, US Optics scopes had a mechanical attractive flair. It was like looking at top-fuel race engine, you could see all the little things that made it work its magic, and that enticed me even further.

That first US Optics scope was an ER-25, it was the first but far from the last. I’ve since had four more, with the latest being the newest offering from US Optics, the Foundation Series 25X. The Foundation series is USO’s latest line of top tier telescopic sights, made here in the US. The FDN25X boasts some impressive features, some you would expect, and others you might miss if you didn’t pay close attention. The 25X uses a fairly standard 34mm tube and 52mm objective, manufactured from 6061 T6 aluminum, it shares a nearly identical body with its predecessor the B25. But there is more, the FDN25X has the new EREK3 elevation turret with 11 MRAD per revolution, a 180-degree throw magnification ring, the new JVCR reticle (my favorite) with illumination available in red, blue, or green, smooth parallax adjustment, and an internal bubble level.


As I opened the box of the 25X and first picked it up, I was surprised at the weight. At thirty-four and a half ounces, it’s not exactly light but it seemed light for its size. I was expecting it to weigh more. I surely wasn’t going to waste much time, I wanted to get this scope mounted and get shooting with it. I mounted it on the rifle it was ordered for, my custom built 257 Blackjack. It is a lightweight carbon fiber hunting rifle to haul all over these Rocky Mountains for Mule Deer, Elk, and likely a few Antelope as well. The 25X makes a great companion optic for the Blackjack, it stays supersonic beyond two thousand yards, and its energy, drop, and wind deflection makes it ideal for long-range shooting. The 25X has been designed and built for just such shooting, with high-quality lenses to give a clear picture of distant targets. The JVCR reticle gives fine wind holds and holdovers, with .1, .2, and .5 subtensions.

JVCR Reticle detail, and green illumination

So with the 25X mounted in rings on a 20 MOA scopebase, I wandered off into the hills to get it zeroed and to put it to the test. Zeroing the scope was simple, the new EREK3 elevation turret was easy to figure out with a brief revision of the manual. I removed the center screw on top of the turret and adjusted my reticle with the provided hex wrench. After a couple adjustments, it was zeroed perfectly and my elevation set to zero. Normally I slowly work my way out from closer targets to more distant ones, but that day, I went straight for the long shots. The first shots after zero were 1230 yards, I dialed 6.5 MRAD on the EREK3, and fired a few shots. After getting the wind call right, they were hammering the steel. The EREK3 turret is a good combination of stiff, and crisp. Not too hard to turn, but firm enough to avoid accidental movement.

As it happens, my first trip out with the FDN25X was a shoot with Donald Trump Jr. He was impressed by performance of the 257 Blackjack, and the FDN25X

The clicks are both audible and tactile, adjustments are easily made from the shooting position by simply counting the clicks either felt or heard. The magnification ring is also a welcome improvement, with only 180 degrees of rotation, you can go from 5x all the way up to 25x with one movement. Instead of having to release and turn again like other scopes. It’ also easier to turn than previous models.
After zeroing my scope, I swapped out the scope base for a 30MOA, to get the scope closer to an internal mechanical zero (to avoid the extremities of erector movement). And with it freshly zeroed, the turret had a full twenty-one MRAD of elevation available. It is highly unlikely I will ever use that much elevation, according to my ballistic computer, twenty-one MRAD will take the supersonic Blackjack to 2159 yards.

The EREK3 elevation, and US #1 windage turrets

The JVCR reticle is one of my favorite reticles, I’ve got another one in another US Optics scope. The .2 MRAD marks are all over the reticle, giving a quick and easy reference for adjustments. The open center floating dot makes a perfect reference point when trying to shoot tiny groups on paper, and the open space around it will make it easy to hold center on any of the animals I plan on hunting this fall. I ordered green illumination on the scope, mainly because I’ve had red on every other scope I’ve ever had and wanted to see something different. I’m not overly worried about it, as illumination has rarely been used in most hunting scenarios I’ve been in. But for that occasional need, it is sure nice to have.

One little thing that I found that did bug me perhaps, is an abnormal crescent shaped shadow when the scope is dialed to either of its extremities. This is normal as US Optics has it listed under their FAQ’s on their website. To be fair, it is only visible at low power (less than 8x), and only when the EREK3 turret is almost all the way up or down. I think it is very unlikely that it will ever be an issue, because if Im dialed all the way up, I’ll very likely be zoomed in at least to 12x or more. And if it is an issue bottoming out the scope, then you’ll need to use an additionally canted base. Like I said, a small issue, but one you may want to know about.

The anti-cant bubble inside. When looking thru the scope and focusing on the target, the highlight of the bubble is seen at the bottom of the reticle

Another very cool feature of the Foundation 25X is the internal level or anti-cant device as it’s often called. I always loved the idea of having it inside the scope, but so many times its been done poorly. Not that I have anything against it being external, especially good ones you can see from the shooting position. But it is so much nicer to see in real-time, through your aiming eye without taking it off the target. The way US Optics executed this level is very nice, I ordered the internal level, but it is so subtle that I didn’t even notice it the first time I looked through it. It is tucked neatly at the bottom of the field of view, and like I said, its so low profile that you actually have to make an effort to see it. I’m not sure if the engineers at USO want you to look at the actual bubble itself, or if you are meant to see the highlight reflecting on the bubble as your reference point, either way, it is very handy when you’re in the shooting position.

I also tested the scope for actual click value, which can vary greatly in rifle scopes. I tested the click value by measuring the turret movements against the values of the reticle, as well as against a ruler at a set distance. By doing this you can tell if the clicks actually represent the value claimed. I’ve never tested one that came out perfect, but this one is close enough for my purposes. Under 10 MRAD of adjustment, the actual value was no more than .02 MRAD off of claimed. And at 20 MRAD, it was just over a tenth MRAD from claimed value. I am not a rocket surgeon, but I think its safe to assume that the difference between claimed and actual is spread progressively across the curve as elevation increases.
In addition to testing click value, while I had the scope clamped down solid I also checked the tracking and for reticle cant. Cranking the turrets up down and left and right shew no inconsistency, they always returned back to the exact same spot as I counted the clicks. No noticeable movement in the reticle either, as I zoomed from one magnification to another.

The only thing I haven’t been able to test so far with the Foundation 25X, is its durability over time. My First US Optics scope took such a beating I was sure it would break, banging into rocks, falling off the tailgate onto concrete attached to a twenty-pound rifle, stuff like that. But I was blown away when not only did it survive these events, but didn’t even lose zero. That is a pretty hefty standard to live up to, and I hope that the Foundation scopes are up to it. Time will tell, I certainly don’t plan on dropping it, or bashing it against rocks, but who knows what the future holds?

There is no way this rifle and scope aren’t coming with me for hunting season this year. The 257 Blackjack will light up anything I intend to hunt, and coupled with the impressive view from the Foundation 25X, it should be unstoppable. I am extremely anxious to get up into the high country, and get comfortable and effective with this rifle and scope. You will no doubt be hearing from and seeing more pictures of us in the fall.
-CBM