For many years, the Swarovski Optik website featured a blog with interesting technical articles. (Unfortunately some of these articles have been taken offline.) In the “On Target” series of blog stories, Swarovski provided a handy explanation of how optics systems work, with exploded diagrams of rifle scopes, spotting scopes, and binoculars. We’ve reproduced the key diagrams here. CLICK HERE for Swarovski On Target Archive.
Scope Terminology
Focusing Lens
The focusing lens is an adjustable lens inside the optical system for focusing the image at different distances…. In the case of rifle scopes, apart from focusing, the focusing lens also facilitates parallax compensation.
Objective Lens
The objective lens is the optical system’s front lens group facing the object and operates like a converging lens. Its purpose is to display an image which, at the image plane, appears upside down, laterally transposed and reduced, and which is subsequently displayed correctly again by the reversal system.
Diopter Adjustment
For rifle scopes, the reticle can be focused using the diopter adjustment on the eyepiece, thereby correcting any visual impairment. [Editor’s Note: Movable eyepiece diopter adjustment is not offered on all rifle scopes. It is a useful feature on Swarovski and other premium scopes. This allows shooters who need eyeglasses to get a sharply focus image even without wearing corrective lenses. Of course shooters should always wear ANSI-certified eye protection. With the diopter, folks who need correction can use inexpensive, non-Rx safety eyewear instead of expensive prescription safety glasses.]
Reversal System
The purpose of the reversal system is to reverse the image by means of prisms in binoculars and telescopes, and lenses in rifle scopes….The lens reversal system is needed in rifle scopes to control the variable magnification and move the exit pupil[.]
Resource tip by ELR Researcher. We welcome reader submissions.
Father’s Day is Sunday, June 15, 2025. Many leading vendors are running Father’s Day sales and promotions. You’ll find major savings — up to 45% — on a wide selection of products. Scopes, reloading tools, dies, ammo, and reloading supplies are marked down this week. And there are deals on rifles, pistols, and shotguns.
Powder Valley Outdoors
Powder Valley Outdoors is running a major sale this week, June 10-15. There are discounts on ammo from Federal, CCI, Remington, Hornady, Barnes (and other mfgs.) with savings up to 39%. In addition, Hornady brass and reloading tools are on sale. From the Powder Valley Sale Page (left column) you can select the type of product and the manufacturer.
Palmetto State Armory
Palmetto State Armory (PSA) is running a Major Father’s Day Sale. A huge selection of products are on sale including AR uppers, AR lowers, complete rifles, handguns, scopes, ammo, triggers, magazines, and more. Shown below are four of the hundreds of sale items.
EuroOptic.com
If you need a scope, rangefinder, or a new hunting rifle, head over to EuroOptic.com this week. There are major deals on products from a dozen companies. There are great deals on optics from Sightron, Leupold, SIG Sauer, Eotech, and Meprolight with savings up to 45%. In addition, a wide range of firearms (rifles, pistols, shotguns) are discounted this week. There is also a Father’s Day Giveaway contest with the winner getting a new CZ Shadow 2 pistol valued at $1,449.00.
MidwayUSA Sales
MidwayUSA has some great items on sale as part of a Father’s Day Gearing Up Sale. In addition, there is FREE SHIPPING with orders over $99 (Code FS060325). Here are six noteworthy deals from MidwayUSA offered this week. There are hundreds of other bargains.
Brownells Specials This Week
Brownells is also running a sale this week, but not specifically for Father’s Day. There’s a large selection of products on sale right now including magazines, triggers, dies, cleaning rods, ammo, and even the popular Garmin Xero C1 chronograph. CLICK HERE to view all items on sale (2562 total as this is released).
Brownells is a well-known retailer of guns, gun parts, tools, accessories, ammo, and pretty much everything gun-related. What you may not know is that Brownells has a very active video production department that releases new “how-to” and product information videos every week. These videos offer helpful advice on gun cleaning/maintenance, reloading, as well as selecting/assembling components for various kinds of rifles. And every week Brownells serves up a new products video. There now over 3000 videos on the Brownells YouTube Channel, which is truly a remarkable resource.
Here are seven of our favorite videos from Brownells. There’s a helpful guide to scope installation, a guide to using the OAL tool properly, and a good video on building a rifle with a Howa barreled action. There’s a helpful video on air travel with rifles, and all gun owners should watch the video on ammunition storage.
Scope-Mounting — Common Mistakes to Avoid
Always be careful when mounting a rifle scope. This isn’t a super-complex or highly technical task, but there are ways you can mess it up. This video explains common pitfalls to avoid when mounting a scope.
1. Make sure the rings don’t touch ANY part of the turret housing, objective bell, or eyepiece.
2. Be certain the scope rings are tightly clamped to the scope base. Grasp the scope with one hand and the rifle with the other, then ensure there is no play.
3. Make sure there’s clearance between the objective bell and the rifle. No part of the scope should touch the rifle itself.
4. NEVER over-tighten the scope rings. You can actually crush the scope tube and damage the optic beyond repair. Stick to the torque specs!
Affordable Precision Rifle Build with Howa 1500 Barreled Action
In this video, Caleb from Brownells walks through a step-by-step build of an affordable precision rifle using a Howa 1500 barreled action, MDT stock, and Vortex optic — putting together a highly capable long-range setup for under $1,200. The video covers key components and shows the assembly tools needed (4:38). The video explains how to build a reliable, accurate bolt gun on a budget, with honest insight into gear selection and assembly techniques. From the stock and trigger to rings, base, and scope setup, this video is a very helpful guide for anyone looking to build an affordable precision rifle. Installation of the Howa 1500 barreled action into the MDT stock is shown in detail at 6:00 minute mark.
How to Use Hornady OAL Tool and Hornady Bullet Comparator
Gun Tech Steve Ostrem explains how to properly use Hornady’s Overall Length Gauge to determine length-to-land precisely. The OAL Gauge uses a “Modified Case” that threads onto the tool and holds a bullet. Push on the back of the gauge until you feel the bullet just touch the rifling. (We do this gently at first, tapping the rod a couple time to ensure the bullet is aligned correctly). Once you’ve got the length, then use the tool with a comparator on your calipers to get the length-to-lands. NOTE: We recommend taking the measurement 3-4 times in a row to get a reliable number. With a little practice your should be able to get repeatable measurements within .0015″.
How to Store Ammunition Safely and Securely
This is one of the most popular Brownells videos — with over 2.5 million views. Here’s the deal — ammunition WILL keep for a long time if you store it properly. DO store ammunition in a cool, dry place that doesn’t have wide temperature swings. Temperature cycling will also degrade primers and powder. Put it in airtight ammo cans to keep out the moisture. Tupperware containers will work too. Brownells also recommends putting moisture-absorbing silica packs in your ammo containers. DON’T just keep ammo in factory cardboard factory boxes stacked in the basement, attic, or garage (especially on the floor). Factory ammo boxes can absorb moisture which can degrade primers and corrode the brass cases. Yes, sealed military ammo will usually handle this kind of storage for quite a while, but it’s still not wise.
Air Travel with Firearms — Key Regulations You Must Follow
You can travel on commercial airlines with firearms. But you must follow the TSA regulations, and your particular airline’s rules. First, make sure your guns are UNLOADED before your leave home. Guns need to be carried in proper hard-sided cases that cannot be pried open. Be prepared to unlock the case if the TSA wants to inspect what’s inside. TSA agents can cut the locks if they need to open the case but can’t locate you. If you use special TSA-approved locks, TSA agents have master keys that let them open the case without destroying your locks. You CAN transport up to 11 pounds of ammunition — with restrictions explained in the video.
Cleaning Advice for .22 LR Rimfire Rifles
Gun Techs Steve Ostrem and Caleb Savant debunk some myths about cleaning .22 LR barrels. One myth is that cleaning will harm the accuracy of a .22 LR barrel. Caleb thinks this myth is the result of people cleaning a barrel from the muzzle and damaging the muzzle crown, which CAN diminish accuracy. If it’s done right, cleaning won’t damage the bore. However, you certainly do NOT have to clean your 22 LR’s bore every time you go to the range. But DO clean the action every time you shoot the rifle, especially on a semi-auto. What about shooting a lot of lead bullets? Won’t that lead up the bore? The guys give us the straight skinny on lead fouling, too. When you see your .22 LR rifle’s groups opening up, you may want to consider cleaning.
Must-Have Spare Parts for AR-Platform Rifles
In this video, two knowledgeable gun techs answer the question: “What spare parts should I keep on hand for my AR-15?” On the list are: Gas Rings, Buffer Spring, Extractor Spring and Pin. NOTE: You may want to try the one-piece spiral gas ring rather than the standard rings which require alignment. The cotter pin and cam pin can also easily get lost when the Bolt Carrier Group is disassembled for cleaning. On the lower receiver you’ll want spare springs and detents for the pivot/takedown pins. If you’re using lighter-power springs, keep standard-power spares on hand. If your rifle stops working, swap in the factory-spec springs to find out if the problem is the gun or your ammo. Also, if you have upgraded your trigger, always keep the original trigger as a backup.
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At the request of our readers, we provide select “Deals of the Week”. Every Sunday afternoon or Monday morning we offer our Best Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, optics, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.
NOTE: All listed products are for sale to persons 18 years of age or older. No products are intended for use by minors.
Excellent vendor EuroOptic.com is running a major clearance sale this week on big name optics. You can save hundreds on quality scopes from Vortex, Leupold, Burris, Pulsar, Athlon, Schmidt & Bender, Swarovski and more. Click these links for the optics Clearance Sales by manufacturers: Vortex| Leupold | Burris | Athlon | Schmidt & Bender | Pulsar
⏺️ » Great package for just $11 more than Chrono alone
Right now you can get the Garmin Xero C1 Pro Chronograph by itself for $549.99 at many vendors. However, for just $11 more ($560.99 total) you can get a Garmin Xero C1 Pro Package complete with tripod, charging accessories, and more. This $560.99 package includes Garmin Xero C1 Pro Chronograph, USB Charging Adapters, White Cube, 6Ave Microfiber Cleaning Cloth, USB Car Adapter, P-Bank Battery, 72 Inch Pro Heavy-Duty Aluminum Tripod. That’s a great deal.
⏺️ » Great combo offer for FFP scope and good laser rangefinder
Here’s a good Scope/Rangefinder combo package for PRS/NRL shooters and varmint hunters. For just $499.99 ($200 off) you get both scope and rangefinder. The Vortex 5-25x56mm Venom scope has First Focal Plane EBR-7C MOA reticle, 34mm tube for ample turret travel, and RevStop Zero System. This is a good FFP optic for folks who prefer MOA clicks. The Vortex Crossfire HD 1400 Laser Rangefinder features an HD optical system, three target modes, and red TOLED display. Vortex states this LRF “ranges deer up to 750 yards, trees up to 950 yards, and reflective targets up to 1400 yards.”
4. Midsouth — Sale on Hornady Tools and Accessories
⏺️ » Nearly all Hornady dies, tool and products on sale this week
⏺️ Nice pair of Walkie-Talkie Muffs that can be recharged
Here’s a great item for buddies or family members who hunt together or compete in pair matches. MidwayUSA is offering a matched pair of Walker’s FireMax Rechargeable Muffs for just $159.99, 66% Off MSRP. You never need to buy batteries — these run for 150 hours after charging with a standard USB-C cable. These NRR20 muffs have comfortable Gel earpads and omni-directional microphones. This combo pack includes two earmuffs and two detachable Walkie Talkie units. The Walkie Talkies offer 4 Frequency modes: Universal, Clear Voice, High-Frequency, Power Boost.
If you are looking for a good, tough 12ga defensive shotgun, here’s a fantastic deal. The Citadel Mariner 12ga pump-action shotgun features a durable nickel finish and barrel heat-shield. It comes complete with front and rear sights, an optics rail, plus a shotshell carrier on the left side of the action. This cool pump shotgun is now just $174.91 on sale — an amazing deal, $104 off the normal price.
7. Midsouth — Summer Clearance Sale, up to 50% Off
⏺️ » Huge savings on reloading kits, ammo, and other gear
Midsouth is running a major Summer Clearance Sale right now, with discounts up to 50%. There are major savings on ammo, reloading presses, gun cases and more. For example, you can save $100 on a LEE Six Pack Pro 6000 progressive press with FREE shipping.
⏺️ Excellent, rugged rifle case at a very good price
When flying or driving it’s vital to protect your rifles. A good hard case option (at a great price) is the APACHE 9800 Weatherproof Protective Rifle Case. On sale for $149.99, this 53″-long case is $190.00 less than an equivalent-size Pelican case. Constructed from durable polypropylene, this quality hard case can protect long guns from from impact, moisture, and dust. The built-in purge valve equalizes pressure so you can open the case after changing elevations. NOTE: Case interior dimensions are 50⅜” by 13⅝”.
9. Midsouth — Lee Challenger Press with BONUS Die Set, $83.99
⏺️ » Get good single-stage press AND die set
The LEE Challenger is the world’s best-selling single station press. The latest Gen III Challenger features an ergonomic lever plus convenient drop-tube for spent primers. Right now LEE is offering a FREE carbide die set with the purchase of the LEE Gen III Challenger Press. Chose one of five cartridge types: .223 Rem, 9mm Luger, .38 SPL/.357 Mag, .44 SPL/.44 Mag, and .45 ACP. Another good feature of the LEE Press is the Breech Lock Quick Change Die System — change dies instantly with a twist of the wrist.
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At the request of our readers, we provide select “Deals of the Week”. Every Sunday afternoon or Monday morning we offer our Best Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, optics, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.
NOTE: All listed products are for sale to persons 18 years of age or older. No products are intended for use by minors.
1. Midsouth — Summer Clearance Sale, up to 50% Off
⏺️ » Huge savings on reloading kits, ammo, and other gear
Midsouth is running a major Summer Clearance Sale right now, with discounts up to 50%. There are major savings on ammo, reloading presses, gun cases and more. For example, you can save $100 on a LEE Six Pack Pro 6000 progressive press with FREE shipping.
2. Graf’s — Hornady Aero Match Bullet Sale w/ FREE Hit Indicator
⏺️ » Get cool target hit device with Hornady Bullet Purchases
Here’s a cool deal — you get two flashing Hit Markers with the purchase of 500 bullets. Hornady Aero Match bullets are quality, high-BC projectiles in a variety of calibers and weights. These come in 500-count boxes. Order now and get a FREE Target Hit Marker 2-Pack with every 500-count AeroMatch box ordered. Plus your Aero Match bullet order ships for free. NOTE: If you purchase six of the same type of AeroMatch bullets Graf’s will pull a full case, making the 3000 bullets sequential — guaranteeing great consistency.
3. Amazon — KAER 57″ Gun Safe, $239.99
⏺️ » Great deal for a medium-size, multi-compartment gun safe
Keeping firearms safe and out of the wrong hands is a critical part of gun ownership. If you need a good, affordable gun safe consider the KAER 8-12 Gun Safe (#ad). This 57″ x 21″ x 15″ safe will hold up to a dozen long guns, and has adjustable shelves to hold pistols, ammo, and other valuables. While we recommend a larger and heavier primary safe, this is a good starter safe or a good secondary safe for your reloading room or vacation home. This safe has a numeric KeyPad lock plus an emergency key.
4. Midsouth — ELEY Rimfire Ammo In Stock
⏺️ » ELEY offers really good .22 LR ammo for rimfire matches.
Rimfire shooting is rapidly growing in popularity because ammo is affordable and you don’t have to spend hours hand-loading. If you need great .22 LR ammo for NRL22, rimfire benchrest, or smallbore competition, you’ll definitely want to consider ELEY. Right now Midsouth has a very large supply of ELEY Rimfire .22LR Ammo. A wide variety of popular ELEY ammo types are in stock including: Match, Tenex EPS, Tenex Biathlon, Club, Force, Semi-Auto BR Outlaw, High-Velocity, Subsonic, Team and Bullseye Pistol.
5. Natchez — SIG Sauer Scope Sale
⏺️ » Good scopes for hunters and tac shooters — sale discounts up to 40%
SIG Sauer optics offer good very good performance, features, and quality for the price. And right now SIG Sauer scopes, red dots, binoculars, and weapon lights are on sale at Natchez. With discounts up to 40%, there are some very good choices for hunting and tactical applications. For example, the SIG Sauer 4-16x44mm Tango SPR scope is just $179.99 on sale.
⏺️ » Popular NRR24 electronic ear plugs now 60% Off MSRP
Protecting your hearing is vital when at the range. One popular option is the NRR24 Walker’s Silencer 2.0 Bluetooth Electronic Ear Plugs. These have a good 24-dB sound reduction rating, are pretty comfortable, and can communicate with your smartphone via wireless BlueTooth. Auto-Shut off helps preserve battery life (6-8 hours). Available in black, FDE, or Olive Drab, these rechargeable electronic ear plugs feature a free control App for your SmartPhone. These $99.99 plugs come with: USB Charging Dock with rechargeable lithium battery, 3 sizes of Sure-Lock fins and foam tips, and cleaning brush.
7. Amazon — Revasri 1000 Yard Rangefinder, $37.98
⏺️ » Very low price, but many good features
If you need a basic laser rangefinder and don’t want to spend a lot of money, consider the Revasri 1000yd Rangfinder (#ad). This laser rangefinder for hunters has 7 functions: ranging mode, all-in-one mode, scanning mode, speed measurement mode, two points height measurement mode, golf distance compensation mode and storage mode. This rangefinder has a convenient memory function which will open the mode you used before shutting down.
8. Amazon — Plano Pro-Max 53″ Hard Gun Case, $32.40
⏺️ » Popular case for large rifle, now 35% off
Sometimes you just need a simple case either to ship a rifle or get to the range. Check out the Plano Pro-Max Series Single Gun Case (#ad) now just $32.40 on Amazon. The Pro-Max’s molded latches and padlock tabs offer good security. Measuring 53″ this Pro-Max case is big enough to hold long-barrel F-Class, High Power, and ELR rifles. The case employs patented PillarLock technology for crush-resistant strength.
9. Amazon — Lyman Brass Smith Xpress Case Trimmer, $133.95
⏺️ » Good unit for fast trimming of multiple cartridge types
Trimming brass is critical for precision reloading. One fast, precise, and efficient power trimmer is the Lyman Brass Smith Case Trim Xpress (#ad). The Case Trim Xpress is equipped with an adjustment wheel, which allows case lengths to easily be “dialed in” to .001″ increments. This Xpress trimmer comes with a set of 10 precision bushings to fit most popular bottleneck rifle cases.
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You know that Zeiss riflescopes boast superb glass, excellent controls, and a rock-solid warranty. What you may not realize is how rugged Zeiss scopes are. Zeiss optics are designed for the toughest conditions that hunters may experience. Zeiss understands that hunting optics can be exposed to extreme temperatures, moisture, shock, and vibration.
To ensure Zeiss scopes perform in the toughest conditions, Zeiss tests production-line optics with rigorous testing procedures unrivaled in the optics industry. Zeiss runs Impact Shock Tests with 800 impact cycles at high G-forces. In addition, Zeiss does a continuous vibration test for 1.5 hours. Scopes are also tested in a salt spray environment to confirm corrosion resistance. But there is more — test optics are immersed in water for two HOURS at depth and the scopes are also lab-tested at -40° F in a climate chamber and also subjected to “temperature shocks” from -13° to +122° F. Now that’s some serious testing.
Zeiss does all this elaborate scope testing to ensure its optics perform in all situations, in all environments. View all these tests in this Zeiss video. We think you’ll be VERY impressed:
Impact Shock Test — 800 Cycles
Continuous Vibration Test — 1.5 hours
Water Immersion Test — Validated Waterproof for 2 hours at 13 feet
Temperature Testing — Extreme Temp Shock Test and Sub-Zero Freeze Chamber
Corrosion Resistance Test — 24 Hours in Salt Spray Environment
Monday, May 26, 2025 is Memorial Day. Many leading shooting sports/outdoor vendors are now running Memorial Day Sales over the next few days. You’ll find savings on guns, ammo, reloading supplies, brass, optics, hunting gear and more.
Brownells Memorial Day Sale — Save 15% with Code MD15
Brownells has kicked off a major Memorial Day Sale. Use Code MD15 to get 15% Off $250+ orders. This discount applies to vast range of products, and there are other featured deals with specific discounts. You’ll find great deals on Howa products, optics, AR components and more.
Powder Valley — Big Memorial Day Weekend Ammo SALE
Need ammo? Now’s a great time to buy from Powder Valley, which is running big discounts on factory ammo from many leading sources. Save on rifle, pistol, rimfire, and shotgun ammo from Federal, CCI, Barnes, Hornady, Remington, Frontier, and other leading brands. Savings typically range from 10% to 22% on loaded ammunition during this big Memorial Day Sale.
Precision Reloading Memorial Day Sale
Leading vendor Precision Reloading is offering site-wide discounts this Memorial Day Weekend. With all orders over $99.00 you can get 10% Off your total costs (not including shipping). To take advantage of this 10% Off deal, use Code SAVE at checkout. This sale ends Tuesday, May 27th at 11:59 pm Mountain time.
Palmetto State Armory (PSA) Memorial Day Sale
Palmetto State Armory has a major Memorial Day Weekend Sale underway now. Save on guns, optics, triggers, ammunition and more. A wide variety of AR-platform parts are discounted and there are some great deals on handguns. For example, the Taurus TX22 pistol is now just $229.99, a $170.00 savings off the regular $399.99 price. There are also major savings on optics, with big discounts on Vortex, SIG Sauer, Holosun, and Pulsar Optics. For example, SIG Sauer Buckmaster 10X Binoculars are now just $119.99, a whopping 29% off the regular $169.99 price.
Primary Arms Memorial Day Sale
Primary Arms is running a huge Memorial Day Weekend Sale. Many popular product types are on sale with savings up to $200. You’ll find big discounts on Geissele triggers, FN AR lowers, Magpul Mags, Eotech and Trijicon optics. Plus Benchmark, Kershaw, and Spyderco knives are on sale. NOTE: This is a multi-part sale so discounted items may vary from day to day and new items are added daily.
For years we have touted the advantages of Burris Signature rings, with polymer Pos-Align Inserts. PRS/NRL shooters take note — this technology is available in a beefier, heavy-duty ring system for tactical rifles. The impressive Burris XTR Signature Rings offer six (6) clamping bolts per ring plus strong, dual steel base-clamps that self-center on Weaver or Picatinny rails. These aluminum XTR Signature Rings provide strength and holding power, plus the key benefits of Pos-Align inserts. As impressive as XTR rings are — they aren’t that expensive, with 1″-diameter XTRs starting at about $87.00 per pair (30mm and 34mm XTRs cost a bit more).
The polymer inserts in Signature rings perform three key functions. First, the inserts provide full, uniform scope-to-ring contact, with no need for lapping. You get a very secure “grip” on your scope without ring marks. Second, the Pos-Align inserts can provide elevation “pre-load”. With eccentric (offset) inserts, you can raise the back of the scope relative to the front, gaining up to 54 MOA of built-in elevation, without the need for expensive tapered bases. Third, the offset inserts can be rotated clockwise or counter-clockwise to shift point of impact. This lets you zero your rifle easily while keeping the turrets in the center of their travel.
Burris XTR Signature Rings are offered in 1″, 30mm, and 34mm diameters, and three (3) different heights: 1″, 1.25″, and 1.5″. Each ring set includes two sets of concentric inserts and one set each of the following offset inserts: +/-5 MOA, +/-10 MOA, +/-20 MOA. These allow you to “pre-load” elevation and/or center up your cross-hairs.
– Pre-load Elevation. No need for expensive tapered bases for long-range shooting.
– Correct misalignment caused by off-center receiver holes.
– Correct for bases or rings being slightly off-center.
How to Pre-load Elevation
To add elevation, set the Pos-Align Offset Inserts to raise the rear of the scope and lower the front. As long as there remains sufficient clearance between the front objective bell and the barrel, Burris recommends lowering the front of the scope the most and raising the rear of the scope the least. The amount of actual elevation “pre-load” will depend on the ring spacing (see chart). In the illustration, with 4.75 inches between ring centers, a +/- 20 MOA pair in the front combined with a -/+ 5 MOA pair in the rear will yield +25 MOA of total elevation. (If the rings are positioned further apart, you’ll get less elevation pre-load.)
Using Inserts to Adjust Point of Impact in Any Direction
Although it is convenient and most understandable to refer to the ring inserts as a “bottom” or “top” insert, the inserts may be rotated to any angle within the scope rings. This allows the shooter to correct the point-of-impact in any direction. The drawings below show how the inserts can be rotated to induce both elevation and windage changes at the same time.
Product tip from Boyd Allen. We welcome reader submissions.
What is Parallax?
Parallax is the apparent movement of the scope’s reticle (cross-hairs) in relation to the target as the shooter moves his eye across the exit pupil of the riflescope. This is caused by the target and the reticle being located in different focal planes.
Here’s a good explaination of scope parallax. This video has been watched over 790,000 times.
Why is it Important?
The greater the distance to the target and magnification of the optic, the greater the parallax error becomes. Especially at longer distances, significant sighting error can result if parallax is not removed.
How to Remove Parallax
This Nightforce Tech Tip video quickly shows how to remove parallax on your riflescope.
While keeping the rifle still and looking through the riflescope, a slight nod of the head up and down will quickly determine if parallax is present. To remove parallax, start with the adjustment mechanism on infinity and rotate until the reticle remains stationary in relation to the target regardless of head movement. If parallax has been eliminated, the reticle will remain stationary in relation to the target regardless of eye placement behind the optic.
This popular video, viewed 3.8 million times on YouTube, provides a clear explanation of Minute of Angle (MOA) and how that angular measurement is used. Among novice shooters, there is much confusion over this term. In this NSSF Video, Ryan Cleckner, a former Sniper Instructor for the 1st Ranger Battalion, defines the term, “Minute of Angle” (MOA) and explains how you can adjust for windage and elevation using 1/4 or 1/8 MOA clicks on your scope. This allows you to sight-in precisely and compensate for bullet drop at various distances.
For starters, Ryan explains that, when talking about angular degrees, a “minute” is simply 1/60th. So a “Minute of Angle” is simply 1/60th of one degree of a central angle, measured either up and down (for elevation) or side to side (for windage). At 100 yards, 1 MOA equals 1.047″ on the target. This is often rounded to one inch for simplicity. Say, for example, you click up 1 MOA. That is roughly 1 inch at 100 yards, or roughly 4 inches at 400 yards, since the target area measured by 1 MOA increases in linear fashion with the distance.
More Minute of Angle (MOA) Explanatory Videos
This Gunwerks video explains that Minute of Angle subtends approximately 1″ for each 100 yards (well, 1.047″ to be more precise). That means a Minute of Angle increases in actual measured size the greater the distance of the target from the shooter.
This lengthy (24-minute) video defines Minute of Angle, and uses multiple diagrams to illustrate how MOA angular measurements works. The video also how MOA-based click values translate to point-of-impact changes at various distances.
