May 27th, 2019

TECH Tip: How to Verify Your Scope’s True Click Values

Click Optics MOA turrent verification test

Let’s say you’ve purchased a new scope, and the spec-sheet indicates it is calibrated for quarter-MOA clicks. One MOA is 1.047″ inches at 100 yards, so you figure that’s how far your point of impact (POI) will move with four clicks. Well, unfortunately, you may be wrong. You can’t necessarily rely on what the manufacturer says. Production tolerances being what they are, you should test your scope to determine how much movement it actually delivers with each click of the turret. It may move a quarter-MOA, or maybe a quarter-inch, or maybe something else entirely. (Likewise scopes advertised as having 1/8-MOA clicks may deliver more or less than 1 actual MOA for 8 clicks.)

Nightforce scope turretReader Lindy explains how to check your clicks: “First, make sure the rifle is not loaded. Take a 40″ or longer carpenter’s ruler, and put a very visible mark (such as the center of an orange Shoot’N’C dot), at 37.7 inches. (On mine, I placed two dots side by side every 5 inches, so I could quickly count the dots.) Mount the ruler vertically (zero at top) exactly 100 yards away, carefully measured.

Place the rifle in a good hold on sandbags or other rest. With your hundred-yard zero on the rifle, using max magnification, carefully aim your center crosshairs at the top of the ruler (zero end-point). Have an assistant crank on 36 (indicated) MOA (i.e. 144 clicks), being careful not to move the rifle. (You really do need a helper, it’s very difficult to keep the rifle motionless if you crank the knobs yourself.) With each click, the reticle will move a bit down toward the bottom of the ruler. Note where the center crosshairs rest when your helper is done clicking. If the scope is accurately calibrated, it should be right at that 37.7 inch mark. If not, record where 144 clicks puts you on the ruler, to figure out what your actual click value is. (Repeat this several times as necessary, to get a “rock-solid”, repeatable value.) You now know, for that scope, how much each click actually moves the reticle at 100 yards–and, of course, that will scale proportionally at longer distances. This optical method is better than shooting, because you don’t have the uncertainly associated with determining a group center.

Using this method, I discovered that my Leupold 6.5-20X50 M1 has click values that are calibrated in what I called ‘Shooter’s MOA’, rather than true MOA. That is to say, 4 clicks moved POI 1.000″, rather than 1.047″ (true MOA). That’s about a 5% error.

I’ve tested bunches of scopes, and lots have click values which are significantly off what the manufacturer has advertised. You can’t rely on printed specifications–each scope is different. Until you check your particular scope, you can’t be sure how much it really moves with each click.

I’ve found the true click value varies not only by manufacturer, but by model and individual unit. My Leupold 3.5-10 M3LR was dead on. So was my U.S.O. SN-3 with an H25 reticle, but other SN-3s have been off, and so is my Leupold 6.5-20X50M1. So, check ‘em all, is my policy.”

From the Expert: “…Very good and important article, especially from a ballistics point of view. If a ballistics program predicts 30 MOA of drop at 1000 yards for example, and you dial 30 MOA on your scope and hit high or low, it’s easy to begin questioning BCs, MVs, and everything else under the sun. In my experience, more than 50% of the time error in trajectory prediction at long range is actually scope adjustment error. For serious long range shooting, the test described in this article is a MUST!” — Bryan Litz, Applied Ballistics for Long-Range Shooting.

Permalink Optics, Tech Tip 9 Comments »
December 16th, 2015

How Changing Primers Can Affect Velocity in the .308 Win

primer CCI Wolf .308 Win Reloading

It may seem obvious, but you need to be careful when changing primer types for a pet load. Testing with a .308 Win rifle and Varget powder has confirmed that a primer change alone can result in noteworthy changes in muzzle velocity. To get more MV, you’ll need a more energy at some point in the process — and that potentially means more pressure. So exercise caution when changing primer types

We are often asked “Can I get more velocity by switching primer types?” The answer is “maybe”. The important thing to know is that changing primer types can alter your load’s performance in many ways — velocity average, velocity variance (ES/SD), accuracy, and pressure. Because there are so many variables involved you can’t really predict whether one primer type is going to be better or worse than another. This will depend on your cartridge, your powder, your barrel, and even the mechanics of your firing pin system.

Interestingly, however, a shooter on another forum did a test with his .308 Win semi-auto. Using Hodgdon Varget powder and Sierra 155gr Palma MatchKing (item 2156) bullets, he found that Wolf Large Rifle primers gave slightly higher velocities than did CCI-BR2s. Interestingly, the amount of extra speed (provided by the Wolfs) increased as charge weight went up, though the middle value had the largest speed variance. The shooter observed: “The Wolf primers seemed to be obviously hotter and they had about the same or possibly better ES average.” See table:

Varget .308 load 45.5 grains 46.0 grains 46.5 grains
CCI BR2 Primers 2751 fps 2761 fps 2783 fps
Wolf LR Primers 2757 fps 2780 fps 2798 fps
Speed Delta 6 fps 19 fps 15 fps

You can’t extrapolate too much from the table above. This describes just one gun, one powder, and one bullet. Your Mileage May Vary (YMMV) as they say. However, this illustration does show that by substituting one component you may see significant changes. Provided it can be repeated in multiple chrono runs, an increase of 19 fps (with the 46.0 grain powder load) is meaningful. An extra 20 fps or so may yield a more optimal accuracy node or “sweet spot” that produces better groups. (Though faster is certainly NOT always better for accuracy — you have to test to find out.)

WARNING: When switching primers, you should exercise caution. More speed may be attractive, but you have to consider that the “speedier” primer choice may also produce more pressure. Therefore, you must carefully monitor pressure signs whenever changing ANY component in a load.

Permalink Bullets, Brass, Ammo, Reloading 1 Comment »
October 1st, 2015

Field Test of Nightforce SHV by LongRangeHunting.com

If you’ve been considering the new Nightforce SHV scope for a hunting application, head over to LongRangeHunting.com. There you’ll find an in-depth field test of the 4-14x56mm SHV by Nicholas Gebhart. This is a very thorough review — Gebhardt checks every feature of the scope and comparison tests the SHV against the more costly Nightforce NXS 3.5-15x50mm. Gebhardt even put the SHV scope in his freezer for a weekend to ensure there was no fogging.

NXS SHV scope review long range huntingOverall, Gebhardt was very pleased with the SHV: “Optical clarity, image brightness, contrast and resolution were all extremely good.” The tester also liked the MOAR reticle in his scope. He didn’t think it was too “busy” though he thought the hold-over lines would benefit from numbers: “Nightforce’s MOAR was easy to use and provided a clear sight picture for engaging small targets. The line thickness is perfect for both precise shot placement and visibility. My personal preference however would be for the even hash marks to be numbered for the entire lower portion of the reticle.” Gebhart noted that the SHV’s side parallax knob had yardage marking numbers that proved accurate (and handy to use) — most other scopes just have lines.

Nightforce SHV vs. Nighforce NXS
How did the new SHV stack up against the NXS in a side-by-side comparison? Gebhardt was impressed with the $995.00 SHV, saying it held its own with the pricier NXS model: “I took about 30 minutes to evaluate the optics of the SHV and see how it compared to an older Nightforce NXS 3.5-15X50. Both of these scopes are made in Japan but given the price differential, I expected to see some difference in the optical quality. To my surprise, I couldn’t find any optical difference between the two except for a very slight possibility of a brighter image with the SHV.”

Nicholas Gebhardt longrangehunting.com Nightforce SHV review

CLICK HERE to Read Full Nightforce SHV Scope Review.

View Nightforce SHV 4-14x56mm Specs in Long-Range Hunting Store ($975.00).


Nicholas Gebhardt has been an active hunter primarily pursuing mule deer, antelope, coyotes and prairie dogs since he was old enough to legally hunt. Nicholas is also a precision rifle competitor and a Captain in the Montana National Guard.

Permalink Gear Review, Optics No Comments »
September 9th, 2012

Digital Scale Comparison: GemPro 500, AY123, Sartorius GD503

This article first appeared in 2011.
JayChris, AccurateShooter.com’s IT “guru”, has tested three different digital scales. The first is the relatively inexpensive ($150.00) GemPro 500, the second was the $333.00 Sartorius AY123, which is very similar to the Denver Instrument MXX123 and Acculab-123. Lastly, JayChris tested his $1225.00 Sartorius GD503 lab scale. The 3-way comparison test produced interesting findings. We learned that the AY123 had some serious shortcomings when used to weigh powder. The GemPro 500 performed well for the price, but was quite a bit slower than the big GD503. In speed of response, accuracy of measurement, resistance to drift, and overall reliability, the GD503 was the clear winner in our comparison. Sometimes you do get what you pay for. CLICK HERE for GD503 Review with Videos.

digital scales GD503, AY124, GemPro 500 250

BATTLE of the BALANCES

Three-Way Comparison Test: GemPro 500, Sartorius AY123, Sartorius GD503
Testing Report by JayChris
Precision Weighing Balances, www.balances.com, an authorized Sartorius Distributor, shipped me an AY123 (same as Denver MXX123, Acculab 123, etc.) along with a high-end GD503 force restoration scale. I had purchased the GD503, while the AY123 was a loaner for this comparison test. I included in this test a GemPro 500 scale that I already had. My key objective in this comparison test was to test each scale for measurement drift over time. We wanted to see if the displayed weight of a given object (here a certified test weight), would change over time, or with repeated measurements.

The first test was a “quick” test, where I measured the same weight ten (10) times, in the same order, about every 30 seconds or so. I did this at about the same speed as weighing out powder, maybe a bit slower. This took about 5 or 6 minutes. The second test was more-or-less an overnight test, where I measured the same weight in lengthening intervals, starting every 10 minutes, then every 30, then every 60, and so on. You can see the time series on the included graphs.

digital scales GD503, AY124, GemPro 500 250

TEST SETUP:
– I used the same 100 GRAM Sartorius certified check weight for every test (see photo). Note: 100 GRAMS = 1543.233 GRAINS
– I calibrated each scale within 30 seconds of each other before starting the test.
– I tare’d each scale within a few seconds of each other
– All three scales are connected to the same line conditioning PDU and are located in the same environment (right next to each other)

Measurement Resolution and Display Increments
– The Sartorius AY123 measures to the nearest hundredth of a grain (.00). Increments are in 0.02 grain divisions, i.e. the nearest two hundredth of a grain.
– The Sartorius GD503 measures to the nearest thousandth of a grain (.000). Increments are in 0.005 grain divisions, i.e. the nearest five thousandth of a grain.
– The GemPro 500 measures to the nearest half-tenth of a grain (.05).

NOTE: When weighing powder, I weigh to the nearest .05 grain so any of these provide adequate (or more-than) resolution.

FIRST SERIES Quick Test:

digital scales GD503, AY124, GemPro 500 250

* X-axis is weighing series iteration

SECOND SERIES Time-based:

digital scales GD503, AY124, GemPro 500 250

* X-axis is a time series in minutes-from-0.

THIRD SERIES AY123 “Stable” vs. “Unstable”:

digital scales GD503, AY124, GemPro 500 250

* X-axis is a weighing series iteration

This is a test of the AY123 in “Stable” vs. “Unstable” environment mode. The GD503 was used for comparison. I ran this test to compare the AY123 in “Stable” conditions mode (default) vs. “Unstable” conditions mode, based on anecdotal reports that the “Unstable” mode produces more consistent results. I did not find that to be so. In addition, I found that the weighing time for the “Unstable” mode was extremely slow — taking nearly 5 – 7 seconds per instance to complete a measurement. It then takes a few seconds to return to zero. In the AY123’s default “Stable” mode, it takes a second or so. Based on my testing then, there is no advantage to running the AY123 (or similar clones) in the “unstable mood”. It will simply slow you down.

Observations and Conclusions
Overall, the GD503 was the most consistent, never varying more than .005 (five-thousandths) of a grain, which is about ten times less drift than the next closest scale. The GemPro was “close” behind, never varying more than .05 of a grain. The AY123 was consistently variable and lost significant resolution over time. It was difficult to plot the AY123 results because it rarely settled at a weight for longer than a few seconds — it would routinely come up with a different weight every few seconds, varying by as much as .04 of a grain. I selected the first reading it “settled” on as the “official” reading.

The one thing this test does NOT demonstrate is trickling — our previous Review of the GD503 has a video that shows that nicely. The GD503 gives you near instantaneous read-outs when trickling. By contrast, both the AY123 and GemPro 500 require a “trickle-and-wait-for-update” plan. The GD503 is really dramatically better in its ability to return a “final” weight very quickly. This allows efficient trickling. CLICK HERE for GD503 Review with Videos.

[UPDATE: One of our readers observed that there is a setting which can make the AY123 more responsive (and accurate) when trickling charges: “Note that the video shows the 123 jumping as powder is added. The reason is the scale is in the default setting, which is for single weightings. When changed to ‘Filling’ mode, the scale reacts very quickly, and in my case accurately. Trickling is easy in the ‘Filling’ mode. My experience is that the AY123 is an excellent scale, but is sensitive to environmental factors. The GD503 is way better and is also way more expensive.” — Matt P.]

GemPro 500 Performed Well — Drift Was Usually Minimal and Charges Settle Fairly Quickly
I’ve used the GemPro 500 for quite a while now and have found it to be fairly reliable. However, over one previous loading session I have seen it drift as much as .150 of a grain. I had to go back and re-weigh charges because of this. Therefore, I tend to tare it every five (5) weighings or so which is probably overkill based on one case. I’ve not had that problem since so I am guessing something happened environmentally (maybe I bumped it or something). Overall, the GemPro is not overly sensitive to environment and settles fairly quickly and reliably.

Charges Weighed by SD503 Have More Consistent Velocities, with lower SDs
I’ve loaded a few hundred rounds with the GD503 now. I have not found it to drift more than .010 of a grain in that time. So, now, I only tend to tare it once at the beginning of a load session. I have gotten extremely consistent velocities from charges loaded with this scale, with single-digit standard deviations. By contrast, previously, my best efforts usually resulted in standard deviations (SDs) in the low teens.

Based on my experience testing the AY123, I would not choose this scale to load powder with. The readings are just too variable. The slightest environment factors (breathing, hand movement, etc.) cause large changes in results. I tried to load some rounds using this scale (backed by my GD503 to verify) and I couldn’t do better than a few tenths of a grain, and that was with considerable effort. The Sartorius AY123 is really the wrong tool for the job when it comes to measuring powder.

Thanks to Precision Weighing Balances for providing the AY123 for comparison. The other two scales, the GemPro 500 and GD503, I purchased on my own nickel. [Editor’s Note: When purchased in 2011, Jay’s GD503 cost approximately $900.00. The current 2012 price at Balances.com is $1225.00.] All three of these digital scales can be purchased through the Precision Weighing Balances webstore:

GemPro 250 | GemPro 500 |AY-123 |GD503

Permalink Gear Review, New Product, Reloading 8 Comments »
December 7th, 2007

Bullet Test Tube for Hunters

Sinclair Int’l now carries the Bullet Test Tube. This unique bullet-testing system uses cardboard tubes filled with a reusable plastic-like test medium. Field & Stream named the Bullet Test Tube a “Best of the Best” product in 2006. According to Sinclair, this system is the only bullet-testing medium that lets you measure wound cavity in detail including volume. To reuse the testing medium, simply melt the expansion material in a standard 1.5 gallon crock-pot and pour it into a replacement target mold.

If you wish to capture the bullet after it passes through the test medium, add the Xtender accessory which slips on the end. This allows hunters to examine bullet integrity as well as wound cavity. Sinclair Int’l prices the Bullet Test Tube at $61.25, while the Xtender is an additional $57.60.

Bullet Test Tube

For more information, read this Test Tube FAQ, or Click the screenshot below to watch a QuickTime Video that demonstrates the whole process.

Bullet Test Tube

Permalink - Videos, News No Comments »