Jul 182016

Review of the U.S. Optics LR-17 3.2-17×44 Illuminated Optic

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Les (Jim) Fischer

July 18, 2016

Table of Contents:
– Background
– Unboxing and Physical Description
– Reticle
– Comparative Optical Evaluation
– Mechanical Testing and Turret Discussion:
– Summary and Conclusion
– Testing Methodology:  Adjustments, reticle size, reticle cant
– Testing Methodology:  Comparative optical evaluation


U.S. Optics LR-17 .32-17x44mm in Bobro dual lever mount atop Remington 5R

U.S. Optics LR-17 .32-17x44mm in Bobro dual lever mount atop Remington 5R



Over the past number of years I have done quite a few reviews of U.S. Optics products. During most of those years, my primary long range scope was one or another U.S. Optics SN-3 3.2-17x44mm scope. This model has since been renamed the LR-17 in a much needed bid to make the USO product line, which had a number of very different designs under the SN-3 designation,  a bit less confusing. Also during that time, U.S. Optics modernized its production methods in order to gain ISO 9001 certification, changed from a totally custom maker to one with some standard models, began to offer it’s products via some retailers, and was purchased internally from the founder’s son by some of its employees. Probably the most important of these was the ISO 9001 certification because of what those changes brought to U.S. Optics. The previous organization of production focused completely on one-off customs was not very efficient. This inefficiency led to higher costs and more QC problems than was possible. Since the change, the greater efficiency has not only improved QC but allowed USO to actually lower prices on a number of models. I probably don’t need to tell you that nobody else has lowered prices on existing models. Do you remember what an S&B PMII 5-25x went for 5+ years ago? I do, and it wasn’t the $3.74k it goes for now. I actually had to add another $500 to this just from the time I started this review to when I finished it. The scope has now basically doubled in price over the years. We in the firearms industry have grown accustomed, in recent times, to increasing prices on existing products though S&B is really in a class of it’s own in magnitude. This general price increase is a byproduct of inflation, currency fluctuations, and most importantly, soaring demand from a series of panic buy events. It is decidedly not the norm for products produced in a capitalist economy to behave this way. The norm is the ever greater efficiency and cheaper prices you see on say flat screen TVs. This year I have seen the reality of this begin to come home for companies in the firearms industry as product stock is soaring and some, seeing the writing on the wall, have slashed prices. Perhaps USO was ahead of the curve in understanding this, or perhaps it is all internal numbers and has little to do with macroeconomics. In either case, USO has lowered prices and quite a few others will have to do so as well.

I often get asked by people what is new and better in optics and this review somewhat addresses that new is not always better. It has been my experience that many new designs, which rely much more heavily on computer simulations than older designs, could have used some more hands-on prototype testing. There are a lot of compromises in optical design that are difficult to quantify and, more and more, I seem to be encountering designs that are difficult to use due to some of the design choices. Of particular concern are problems with having the whole image focus substantially in the same location so that your eye does not have to move around behind the optic to get different parts of the image in focus. I did not see this issue much in the past, but it has become prevalent, particularly in physically short and high magnification multiplier designs. This review looks at a very old optical platform that is a less aggressive design in its physical dimensions than many new competitors but also more thoroughly tested and often better optical design.


Unboxing and Physical Description:

For years, USO has been famous for its plain crappy white box with U.S. Optics tape. It has even become something of a cult symbol for its total divergence from the industry trend and complete lack of marketing. It reminds me somewhat of the boxes that Nikkor lenses come in, which have remained unchanged since at least the 1980’s:  black and gold and stylistically obsolete. U.S. Optics has since updated this design to include a snazzy slipcover and more aesthetic end sticker, but has, I think wisely, elected to retain the core, original, classic, tapped white box. The example I am reviewing today was one of the first to bear the new LR-17 designation and, by a printer’s delay, predated this new slipcover as well as new manuals which are a glossy, bound, affair in contrast to the  previous corner-stapled printed loose sheets.

Inside the box whose plainness I am far too enamored with, you will find what I consider the usual adornments of a scope. There are factory marked caps, a manual, and the wrenches necessary for adjustment. In the case of a USO with an EREK knob, you will also get the cap with a hole in it for EREK adjustment.


U.S. Optics LR-17 3.2-17x44mm with box and accessories. New manuals and box sleeves were not yet ready at the time I obtained this review sample.

U.S. Optics LR-17 3.2-17x44mm with box and accessories. New manuals and box sleeves were not yet ready at the time I obtained this review sample.

The appearance of the LR-17 itself is unique. The T-Pal (turret parallax) feature makes for a long saddle section of the scope that, at 2.89″, does not accommodate many of the existing one piece mounts. There is no integration of features in this design so elevation, windage, illumination, and parallax are all separate knobs. The usual configuration is with illumination and windage one in front of the other on the right side, but configurations actually exist with left hand windage. The EREK knob itself is very low and very wide. This is a well loved feature of the design and the wide nature makes it easier to read and gives better feel while it remains low and unobtrusive. A joint will be noticed in the objective bell. It is unusual for a scope of this cost to have a multi-piece main tube, but USO does due to material length limitations of the lathes used. At 2.1 lbs and 16.5″, the LR-17 is about average for weight and a bit longer than most competing scopes. The 3.2-17x range comes out to a 5.3x erector ratio. This is still a little above average, but was unheard of when the design first came out.



The production LR-17 comes in seven reticles. Two of these are in IPHY. They are the PCMOA and MDMOA reticles. Five of the designs are mil. They are the Gen II XR, MPR, H-102, H-59, and, most popular, GAP design.  These designs represent only a piece of what was once the whole custom catalog, beyond which USO used to actually work with users to create new reticles (this was obviously not free and had substantial minimum orders, so don’t go bugging them about it). The result of this is that some old esoteric reticle designs such as “Jon Beanland” are floating around and some new designs, the Big Dog Steel reticle comes to mind, have been proposed. I mention all of this reticle strangeness because the existing mil reticle options are not what I would like to see. They really whittle down to basic or Horus in nature and it is my hope that at some point the offerings might be improved.

GAP reticle as used in many U.S. Optics models. No exotic dear were harmed for this magnificent photo.

GAP reticle as used in many U.S. Optics models. No exotic dear were harmed for this magnificent photo.


Comparative Optical Evaluation:

The USO 3.2-17x design, in one example or another, has been more tested than any other optical design by me. I have used it, with my Zeiss Conquest 4.5-14x, as reference scopes in virtually all of my reviews. This is probably much to the annoyance of many a scope manufacturer as both of these are very solid optical designs in terms either of cost per performance or absolute performance and both are also very old designs.

In my latest set of reviews, I sat a brand new LR-17 side by side with a Vortex Razor HDII 4.5-27×56, Nightforce SHV, Burris XTR II 4-20×50, Leupold MK6 3-18×44, and my trusty Zeiss Conquest 4.5-14×44. To learn more about the exact methodology of the testing, please refer to the testing methodology section at the conclusion of the article.


The comparison lineup from left to right- Vortex Razor HDII 4.5-27x56, Nightforce SHV 4-14x56, Burris XTR II 4-20x50mm, USO LR-17 3.2-17x44, Leupold MK6 3-18x44, Zeiss Conquest 4.5-14x44* not pictured*

The comparison lineup from left to right- Vortex Razor HDII 4.5-27×56, Nightforce SHV 4-14×56, Burris XTR II 4-20x50mm, USO LR-17 3.2-17×44, Leupold MK6 3-18×44, Zeiss Conquest 4.5-14×44* not pictured*


The LR-17 and Razor HDII were pretty clearly in a league of their own. In many ways, parsing the optical performance of the Vortex Razor HDII 4.5-27×56 vs. the USO LR-17 is splitting hairs. Both were quite exceptional and I doubt very much anyone will be unsatisfied with the optical performance of either. Some of what we are here to do though is split hairs, and since we can probably see those hairs though either of these two scopes, we had best commence – keeping in mind the difficulty of this as the slightest changes in lighting as cloud thickness changed (or whatnot) were enough to constantly make me change and reverse opinions about who had better resolution (USO), contrast (USO), or color rendition (Vortex). A more certain judgment is that the eyebox on the Vortex was more forgiving of head position than the USO and that its edges were better. Also certain is that Vortex suffered more image loss as adjustments were moved near max adjustment range and farther from optical center, though given the much greater range of the Vortex in adjustment vs. the USO, it would be unfair to fault it on this. It should be noted that this USO has the largest field of view for any high power scope I have tested, an especially impressive statistic given its exceptional edge-to-edge clarity.

In general, given the many hours of shooting and testing I have had behind LR-17 designs, I can say with confidence that they are very well balanced and comfortable optical platforms that do not lag in optics relative to the much newer optical designs with which they now compete. It was good fortune that the most recent scope I tested the LR-17 against was the Vortex Razor HDII 4.5-27x, as this is probably the hottest new scope on the market today. The LR-17 is right on par with the HDII in optical performance, though the HDII does have a more aggressive 6x erector ratio.


Mechanical Testing and Turret Discussion:

Here is where we talk about the EREK knob. This was one of the first knobs that could be used in a zero stop fashion. I say could be because the concept of a zero stop was not really a thing when it was designed. It just ended up being about to be used that way when people had a mind to or perhaps people got a mind to because it could be. It is really kind of hard to pin that down. The original intent of the design was to have a low elevation knob and yet still allow full vertical travel of the erector within the main tube. Because of this origin, the EREK, when used as a zero stop, is actually a little tricky to set up. Let’s talk about the parts of the knob. There is a sleeve with graduations that can easily be removed and which is held in place with either a cap with a hole or a solid cap, a knob that clicks when moved, and a plunger in the middle that can be adjusted with a hex wrench and does not click when moved on its own. You probably won’t have any problem figuring out the sleeve part. You can set it wherever you want with no effect on the point of aim. The other two parts are trickier. You would think that you could zero the scope, put the hex wrench in the center hole, and hold it stationary while turning the knob down to stop. This is not the case. Moving the outer knob while the plunger is stationary does move the impact point. That is the trick, both the plunger and the knob independently move the point of aim. To easily adjust the EREK for use as a zero stop, you therefore need another tool:  a magnetic bore sight. What you do is to zero the scope on target as you normally would. You then attach the bore sight to the barrel and make note of where on the grid of the bore sight your point of aim is. You can then bring the knob down to zero and use the plunger to return on the grid of the bore sight to your correct point of aim. It is a step, and a tool more complicated than most current zero stop designs, but it does work and, like most plunger based zero stop designs, it also allows you a choice of how far below zero the stop is set at. This is something many designs do not allow to be changed. I hope you find this explanation helpful, as setting the EREK knob as a zero stop has frustrated many shooters who did not understand that the plunger and knob both independently move point of aim. With the correct understanding and tools, the adjustment can be done with only minor inconvenience vs. newer designs.

The EREK knob itself has a very USO feel to the adjustment. That is to say that the clicks feel very positive but also very smooth. Moving up or down does have a different feel and sound, but both are pleasing to my ears. I am a fan of this feel as some other designs are so stiff that it is hard not to over adjust and they always feel like the thing’s going to break, while other designs are kind of sloppy with play within a click. The USO has positive clicks, but they are not very stiff and are quite smooth. Because of the large diameter nature of the knob, the clicks are also well spaced and easy to read. The knob on newer EREKs is 11mil per turn with no tactical turn indicator. The previous knob was 9 mil. I am not sure why USO chose 11mil as it makes 2nd turn use tricky. Though the 20.5 mil total travel in the LR-17 is less than most new scopes, it is still enough that, with an angled base, 2nd turn use is clearly possible. Obviously, the thought is that the 11mils will be all that is utilized. Perhaps that is fine, as few shooters will ever use more than 11mils and those shooters would presumably be interested enough in high travel to chose a design that excels at that.

Usually, with my adjustment testing, I am not able to supply any sort of sample size as I only have one scope on hand. With the LR-17, however, I have been able to test two, as well as an additional two USO 5-25x designs that may also offer insight.

The adjustments on the newest LR-17 I had on hand were .1 mil small at 10mils, reading 10 mils at 9.9 actually traveled and .2 mils small at the full 14 mils traveled from optical center to stop (this is obviously more than spec for travel, by the way.) The reticle was also 1% small so, to the shooter, there would be no disagreement between the reticle and adjustments out to beyond 10 mil. No deviation in windage was noticeable out to the 4 mils that I can measure, but, given the difficulty of getting the target squared horizontally with the shooter, there is not much to say about that. No shift in point of aim with power change was recorded and the reticle was canted less than .05% counter-clockwise.

In addition to that late 2013 scope, I tested a 2006 5-25x, a 2010 5-25x, and a 2011 3.2-27x. Their respective elevations registered:  .2 mill large at 7 mils (full range), perfect at 10 mils, and perfect at 10 mils. The fist two had correctly sized reticles and the third was small by .05%. None of these scopes had any problems with point of aim changing with power change. The 2006 5-25x notably also would not focus down to the 100yd spec, but would instead only go to maybe 130yd. That is more annoying than you would think.

This sample size gives us some insight into the range of range of accuracy in USO scopes. Only the oldest had what I would consider unacceptable deviation of 2% in adjustment magnitude. The middle two were pretty spot on and the new one deviated in both reticle size and adjustment magnitude by 1%. Errors that, due to consistency with each other, would be unlikely to be noticed by a shooter and, I expect, were probably caused by the same lens positioning as each other.


U.S. Optics LR-17 EREK elevation knob with outer sleeve removed.

U.S. Optics LR-17 EREK elevation knob with outer sleeve removed.


Summary and Conclusion:

The U.S. Optics 3.2-17x optical platform is now well over 10 years old, but as we can see, gives up nothing to new designs in optical performance. In fact, I would say it is still better than par in that regard, being very comfortable to be behind with exceptionally good clarity and field of view. It remains one of my overall favorite optical designs. In terms of features, this design was one of the first to offer what are currently considered the basics of a long range tactical scope with a zero stop feature, high revolution elevation knob, and matching accurate knobs with reticles. The execution of the elevation knob is starting to show its age as newer models are less confusing to the user, quicker and easier to set, and often offer additional features such as a pop-up turn indicator or lock. I would not complain if USO saw fit to update the design of the EREK knob.

The LR-17 should serve to remind us of a couple truths. Introducing new models is not the only way to improve your product. Improving manufacturing to allow for better QC and lower cost with an existing strong product is also a good way to improve your offerings. Newer is also not always better as anybody can tell you when it comes to the shooting sports in general. The LR-17 remains substantially better than most much newer competing designs and remains one of my favorite long range optics.

Here is Your Pro and Con Breakdown:

Excellent optics
Comfortable for the eye to be behind
Particularly good field of view
Good feel to the adjustments
Excellent warranty and reputation for service

EREK knob is less feature-laden and more difficult to adjust than many competitive offerings
Reticle designs are very average
Tracking on my sample was average not excellent
Large footprint


Testing Methodology:  Adjustments, Reticle Size, Reticle Cant

When testing scope adjustments, I use the adjustable V-block on the right of the test rig to first center the erector. About .2 or so mil of deviation is allowed from center in the erector, as it is difficult to do better than this because the adjustable V-block has some play in it. I next set the zero stop (on scopes with such a feature) to this centered erector and attach the optic to the rail on the left side of the rig.


Test rig in use testing the adjustments of the Vortex Razor HD II 4.5-27x56
Test rig in use testing the adjustments of the Vortex Razor HD II 4.5-27×56


The three fine threaded 7/16″ bolts on the rig allow the scope to be aimed precisely at a Horus CATS 280F target 100 yds down range as measured by a quality fiberglass tape measure. The reticle is aimed such that its centerline is perfectly aligned with the centerline of the target and it is vertically centered on the 0 mil elevation line.


Horus CATS 280F target inverted and viewed though the Leupold Mark 6 3-18x44
Horus CATS 280F target inverted and viewed though the Leupold Mark 6 3-18×44


The CATS target is graduated in both mils and true MOA and calibrated for 100 yards. The target is mounted upside down on a target backer designed specifically for this purpose as the target was designed to be fired at rather than being used in conjunction with a stationary scope. Since up for bullet impact means down for reticle movement on the target, the inversion is necessary. With the three bolts tightened on the test rig head, the deflection of the rig is about .1 mil under the force required to move adjustments. The rig immediately returns to zero when the force is removed. It is a very solid, very precise, test platform. Each click of movement in the scope adjustments moves the reticle on the target and this can observed by the tester as it actually happens during the test. It’s quite a lot of fun if you are a bit of a nerd like I am. After properly setting the parallax and diopter, I move the elevation adjustment though the range from erector center until it stops, making note every 5 mils of adjustment dialed of any deviation in the position of the reticle on the target relative to where it should be and also making note of the total travel and any excess travel in the elevation knob after the reticle stops moving but before the knob stops. I then reverse the process and go back down to zero. This is done several times to verify consistency with any notes taken of changes. After testing the elevation adjustments in this way, the windage adjustments are tested out to 4 mils each way in similar fashion using the same target and basically the same method. After concluding the testing of adjustments I also test the reticle size calibration. This is done quite easily on this same target by comparing the reticle markings to those on the target. Lastly, this test target has a reticle cant testing function (basically a giant protractor) that I utilize to test reticle cant. This involves the elevation test as described above, a note of how far the reticle deviates horizontally from center during this test, and a little math to calculate the angle described by that amount of horizontal deviation over that degree of vertical travel.

Testing a single scope of a given model, from a given manufacturer, which is really all that is feasible, is not meant to be indicative of all scopes from that maker. Accuracy of adjustments, reticle size, and cant will differ from scope to scope. After testing a number of scopes, I have a few theories as to why. As designed on paper, I doubt that any decent scope has flaws resulting in inaccurate clicks in the center of the adjustment range. Similarly, I expect few scopes are designed with inaccurate reticle sizes (and I don’t even know how you would go about designing a canted reticle as the reticle is etched on a round piece of glass and cant simply results from it being rotated incorrectly when positioned). However, ideal designs aside, during scope assembly the lenses are positioned by hand and will be off by this much or that much. This deviation in lens position from design spec can cause the reticle size or adjustment magnitude to be incorrect and, I believe, is the reason for these problems in most scopes. Every scope maker is going to have a maximum acceptable amount of deviation from spec that is acceptable to them and I very much doubt they would be willing to tell you what this number is, or better yet, what the standard of deviation is. The tighter the tolerance, the better from the standpoint of the buyer, but also the longer average time it will take to assemble a scope and, therefore, the higher the cost. Assembly time is a major cost in scope manufacture. It is actually the reason that those S&B 1-8x short dots I lusted over never made it to market. I can tell you from seeing the prototype that they were a good design, but they were also a ridiculously tight tolerance design. In the end, the average time of assembly was such that it did not make sense to bring them to market as they would cost more than it was believed the market would bear. This is a particular concern for scopes that have high magnification ratios and also those that are short in length. Both of these design attributes tend to make assembly very touchy in the tolerance department. This should make you, the buyer, particularly careful to test scopes purchased that have these desirable attributes as manufacturers will face greater pressure on this type of scope to allow looser standards. If you test yours and find it lacking, I expect that you will not have too much difficulty in convincing a maker with a reputation for good customer service to remedy it:  squeaky wheel gets the oil and all that.

Before I leave adjustments, reticle size, and reticle cant, I will give you some general trends I have noticed so far. The average adjustment deviation seems to vary on many models with distance from optical center. This is a good endorsement for a 20 MOA base, as it will keep you closer to center. The average deviation for a scope’s elevation seems to be about .1% at 10 mils. Reticle size deviation is sometimes found to vary with adjustments so that both the reticle and adjustments are off in the same way and with similar magnitude. This makes them agree with each other when it comes to follow up shots. I expect this is caused by the error in lens position affecting both the same. In scopes that have had a reticle with error it has been of this variety, but less scopes have this issue than have adjustments that are off. Reticle size deviation does not appear to vary as you move from erector center. The mean amount of reticle error is about .05%. Reticle cant mean is about .05 degrees. Reticle cant, it should be noted, Affects the shooter as a function of calculated drop and can easily get lost in the windage read. As an example, a 1 degree cant equates to about 21cm at 1000 meters with a 168gr .308 load that drops 12.1 mils at that distance. That is a lot of drop and a windage misread of 1 mph is of substantially greater magnitude (more than 34 cm) than our example reticle cant-induced error. This type of calculation should be kept in mind when examining all mechanical and optical deviations in a given scope:  a deviation is really only important if it is of a magnitude similar to the deviations expected to be introduced by they shooter, conditions, rifle, and ammunition.


Testing Methodology:  Comparative Optical Evaluation

The goal of my optical performance evaluation is NOT to attempt to establish some sort of objective ranking system. There are a number of reasons for this. Firstly, it is notoriously difficult to measure optics in an objective and quantifiable way. Tools, such as MTF plots, have been devised for that purpose primarily by the photography business. Use of such tools for measuring rifle scopes is complicated by the fact that scopes do not have any image recording function and therefore a camera must be used in conjunction with the scope. Those who have taken through-the-scope pictures will understand the image to image variance in quality and the ridiculousness of attempting to determine quality of the scope via images so obtained.  Beyond the difficulty of applying objective and quantifiable tools from the photography industry to rifle scopes, additional difficulties are encountered in the duplication of repeatable and meaningful test conditions. Rifle scopes are designed to be used primarily outside, in natural lighting, and over substantial distances. Natural lighting conditions are not amenable to repeat performances. This is especially true if you live in central Ohio, as I do. Without repeatable conditions, analysis tools have no value, as the conditions are a primary factor in the performance of the optic. Lastly, the analysis of any data gathered, even if such meaningful data were gathered, would not be without additional difficulties. It is not immediately obvious which aspects of optical performance, such as resolution, color rendition, contrast, curvature of field, distortion, and chromatic aberration, should be considered of greater or lesser importance. For such analysis to have great value, not only would a ranking of optical aspects be in order, but a compelling and decisive formula would have to be devised to quantitatively weigh the relative merits of the different aspects. Suffice it to say, I have neither the desire, nor the resources, to embark on such a multi-million dollar project and, further, I expect it would be a failure anyway as, in the end, no agreement will be reached on the relative weights of different factors in analysis.

The goal of my optical performance evaluation is instead to help the reader get a sense of the personality of a particular optic. Much of the testing documents the particular impressions each optic makes on the tester. An example of this might be a scope with a particularly poor eyebox behind which the user notices he just can’t seem to get to a point where the whole image is clear. Likewise, a scope might jump out to the tester as having a very bad chromatic aberration problem that makes it difficult to see things clearly as everything is fringed with odd colors. Often these personality quirks mean more to the users experience than any particular magnitude of resolution number would. My testing seeks to document the experience of using a particular scope in such a way that the reader will form an impression similar to that of the tester with regard to like or dislike and the reasons for that.

The central technique utilized for this testing is comparative observation. One of the test heads designed for my testing apparatus consists of five V-blocks of which four are adjustable. This allows each of the four scopes on the adjustable blocks to be aimed such that they are collinear with the fifth. For the majority of the testing each scope is then set to the same power (the highest power shared by all as a rule). Though power numbers are by no means accurately marked, an approximation will be obtained. Each scope will have the diopter individually adjusted by the tester. A variety of targets, including both natural backdrops and optical test targets, will be observed through the plurality of optics with the parallax being adjusted for each optic at each target. A variety of lighting conditions over a variety of days will be utilized. The observations through all of these sessions will be combined in the way that the tester best believes conveys his opinion of the optics performance and explains the reasons why.


A variety of optical test targets viewed through the Leupold Mark 6 3-18x44
A variety of optical test targets viewed through the Leupold Mark 6 3-18×44