Red dot sight FAQs

A red dot sight is a non-magnifying (1x) optic that uses a small LED to project an illuminated aiming point onto a coated lens. You look through the lens, place the dot on the target and shoot — there is no need to line up front and rear iron sights.

Because the dot sits on the same optical plane as the target, you can shoot with both eyes open, keep full peripheral vision and acquire a target far faster than with irons. At typical distances the sight is effectively parallax-free, so the dot stays on target even if your head is not perfectly centred behind the lens.

Reflex sight is the broad family. An LED emitter fires forward onto a partially mirrored lens that reflects the dot back to your eye. Almost every “red dot” on the market is a reflex sight.

Open emitter reflex sights have a single lens with the emitter exposed at the base. Enclosed emitter sights wrap the emitter and lens inside a sealed tube or box.

Holographic sights use a laser to reconstruct a recorded hologram of the reticle inside the optical path. The practical differences are a reticle that stays crisp for many shooters with astigmatism, and a window that tends to be larger — at the cost of higher power draw.

Prism sights are a separate category: they use a glass prism and an etched reticle, usually with fixed magnification, and the reticle remains visible even with the illumination switched off.

An enclosed emitter optic seals the emitter and both lenses inside the housing, so rain, snow, mud, lint and dust cannot settle in front of the LED and block the dot. That makes it the more reliable choice for wet British weather and for carry use, at the cost of extra bulk, weight and usually a higher price.

An open emitter optic is lighter, lower and slimmer, which matters on a compact slide or a lightweight rifle. It is the more common choice for range and competition use where you can wipe the lens if needed.

MOA stands for minute of angle. One MOA is roughly one inch at 100 yards, two inches at 200 yards and so on, so a 2 MOA dot covers about 2 inches of a target at 100 yards.

A smaller dot (1–2 MOA) obscures less of the target and is easier to shoot precisely at distance. A larger dot (5–8 MOA) is quicker for the eye to find under stress and at speed, but hides more of the target further out. Around 3–4 MOA is the common compromise.

Many optics now offer a combined reticle — typically a 2 MOA dot inside a 32 or 65 MOA ring — which gives you a fast reference ring up close and a precise dot for a deliberate shot.

A red dot sight is 1x, which is ideal out to the ranges most shooters actually use. If you want more reach without giving up speed, the usual answer is a flip-to-side magnifier — commonly 3x or 5x — mounted behind the red dot. Swing it in when you need it, swing it out and you are back to a true 1x sight picture.

If you expect to spend most of your time at longer distances, a low power variable optic (LPVO) may suit you better than a red dot and magnifier combination.

The specification sheet rarely tells the whole story. The things that consistently differ are: glass clarity and how neutral the lens coating is (cheap coatings add a blue or green tint); how round and stable the dot looks across the brightness range; whether the adjustments move the point of impact accurately and repeatably; how well the housing survives recoil and impact; battery life and whether motion activation actually works; and how the manufacturer handles a warranty claim years later.

If you are unsure which tier is right for what you shoot, email us at support@reddotsight.co.uk and describe your setup — we would rather point you at the right optic than the expensive one.

That is almost always astigmatism in your own eye rather than a fault with the optic. The LED is a very small, very bright point source, which is exactly the sort of thing an astigmatic eye smears.

Three things usually help: turn the brightness down to the lowest setting at which the dot is still clearly visible, wear your corrective lenses while shooting, or move to an optic with an etched or holographic reticle rather than a plain LED dot. If it only appeared recently, it is worth an eye test.

A footprint is the specific pattern of screw holes and recoil lugs machined into the base of an optic and into whatever it bolts to. Two sights can be the same size and still not interchange if their footprints differ.

The patterns you will meet most often are Docter/Noblex, Trijicon RMR, Shield RMS/RMSc, Aimpoint ACRO and Leupold DeltaPoint Pro. Before you buy, check which footprint your mount, adapter plate or milled slide is cut for, and match the optic to it — not the other way round.

Most rifle-format red dot sights ship with, or can be fitted to, a mount for a MIL-STD-1913 Picatinny rail, which has 5.23 mm recoil slots at a fixed 10 mm spacing.

Weaver rails look similar but use narrower, irregularly spaced slots. A Weaver-pattern accessory will often fit a Picatinny rail, but a Picatinny accessory will frequently not fit a Weaver rail. If your platform uses a dovetail rail instead, you will need a dovetail-to-Picatinny adapter.

Height is about where the dot sits relative to your iron sights and your cheek weld.

Absolute co-witness puts the dot in line with the irons, so the front post sits in the middle of the window. Lower one-third co-witness raises the optic so the irons sit in the lower third of the window, leaving a cleaner view for the dot while the irons remain available. On an AR-pattern rifle, lower one-third is typically a 1.93 in mount and absolute co-witness around 1.41 in, but this varies by optic.

If your platform has no iron sights, choose the height that gives you a comfortable, repeatable head position rather than chasing a particular number.

Tighten to the torque figure in the optic or mount manufacturer's instructions, using an inch-pound torque driver. Typical figures fall between 12 and 20 in-lb for optic-to-mount screws, but you should always use the number in your own manual rather than a rule of thumb.

Overtightening is the most common cause of stripped threads, cracked housings and distorted tubes, and it is not covered by warranty. Undertightening loses zero. Both are avoided by using a torque driver.

Follow the manufacturer's instructions for your specific optic and mount. Where thread locker is specified it is usually a medium-strength (blue) product, applied sparingly to the screw threads and left to cure before shooting.

Never use high-strength (red) thread locker on an optic unless the manufacturer explicitly calls for it, and keep all thread locker away from lenses and the battery compartment.

Only if the slide is cut for one. That means either a factory optic-ready slide with a matching adapter plate, or a slide milled to a specific footprint. A sight cannot simply be clamped to an uncut slide.

Two details matter more than people expect: the screws must be the correct length for the milled depth, because screws that are too long bottom out and will not clamp while screws that are too short strip; and if the cut is deep enough to intersect the striker channel, use the plate and hardware specified for that cut.

A quality optic on a quality mount, torqued to specification, holds zero reliably. Nearly every “lost zero” problem traces back to a loose screw, a mount that was never torqued properly, or an adapter plate stacking up between the optic and the slide.

It is good practice to check your zero and re-check screw torque after the first outing with a newly fitted optic, and periodically after that.

The great majority run on a single 3 V lithium coin cell. CR2032 is the most common, with CR1632, CR1620 and CR2016 appearing in smaller pistol-format optics. Some rifle sights use an AA or AAA cell instead.

The exact cell is listed in the technical specifications on each product page. It is worth keeping a spare in your range bag — coin cells are cheap and they always run out at the least convenient moment.

Anywhere from a few hundred hours to several years, and the headline figure always assumes a particular brightness setting. A manufacturer quoting 50,000 hours is quoting a mid-range daylight setting, not maximum brightness, where the same optic might last a few hundred hours.

Holographic sights draw considerably more power than LED reflex sights, so their runtimes are measured in hundreds rather than tens of thousands of hours. Check the quoted setting alongside the quoted hours when you compare two optics.

Motion activation puts the optic to sleep after a period without movement and wakes it instantly when it is picked up or bumped. It is the single biggest contributor to the very long battery lives now quoted, because the emitter is off for most of its life.

Wake times and sensitivity vary between models, and most optics let you disable the feature and run the dot permanently on if you prefer.

It can. A side-loading or top-loading battery tray lets you change the cell with the optic still bolted in place. A bottom-loading tray means removing the optic from the mount, and on a pistol that usually means re-checking zero afterwards.

If you use a bottom-loading optic, many shooters simply replace the battery on a fixed schedule — for example annually — rather than waiting for it to fail.

For anything more than a few weeks in storage, yes. Coin cells can leak over long periods, and the residue will corrode the contacts and can ruin an otherwise perfectly good optic.

Store the optic somewhere dry, with the battery removed and kept separately.

Fit and torque the optic first, then bore sight it — either with a bore sighting tool or, on a platform that allows it, by looking down the bore at a target and bringing the dot onto the same point. This gets you on paper and saves ammunition.

Then shoot a small group from a stable rest at your chosen distance, measure how far the group centre sits from the point of aim, and move the windage and elevation adjustments by the number of clicks that distance represents. Fire a confirming group and repeat if needed. Adjustments always move the point of impact, so if your group is low and left, you adjust up and right.

There is no single right answer — it depends on the calibre, the load and the distances you actually shoot.

Shorter zeroes such as 25 yards are simple and keep the point of impact close to the point of aim across normal ranges. Longer zeroes such as 50 or 100 yards flatten the trajectory over a wider band but need more care up close, where the bullet is still rising to the line of sight and sits below it.

If you are unsure, pick the distance you shoot most often and be consistent about it.

Most red dot sights adjust in 1 MOA or 1/2 MOA increments, which is roughly one inch or half an inch at 100 yards respectively. Some use metric clicks expressed in centimetres at 100 m.

The click value for your optic is on the product page and in the manual. Work out the correction in inches at your zero distance, then divide by the click value at that same distance — a 1 MOA click only moves a quarter of an inch at 25 yards.

Use the lowest setting at which the dot is clearly and comfortably visible against the target. Running the brightness higher than you need makes the dot bloom, which costs you precision and, with an astigmatism, makes the smearing much worse.

Outdoors in bright sun you will need a genuinely high setting; indoors or at dusk you may be several steps down. Optics with an automatic brightness sensor handle this for you, though most still allow manual override.

Remove loose grit first with a blower or a soft lens brush — never wipe a dry, dusty lens, because you will drag the grit across the coating and leave fine scratches.

Then use a lens pen or a clean microfibre cloth with a small amount of proper optical lens fluid, working from the centre outwards. Avoid household glass cleaner, alcohol wipes, paper towel and clothing, all of which can damage anti-reflective coatings.

Most quality optics are sealed and nitrogen or argon purged, and carry a stated ingress rating — commonly IPX7, or a submersion depth in metres for a defined period. That is enough for rain, snow and brief immersion.

Ratings vary widely between models, and an open emitter optic will still collect water droplets on the exposed lens even when the housing itself is sealed. The rating for each optic is listed in its technical specifications.

We ship from a UK-based warehouse and we are primarily focused on UK customers. Where we are able to offer delivery outside the United Kingdom, that option and its terms will be shown at checkout.

Full details are in our Shipping Policy.

Orders are normally dispatched within 7–10 business days after order confirmation, payment approval and any required verification checks. Some items dispatch sooner where stock is immediately available; pre-order and special-order items can take longer.

Once dispatched, typical UK delivery is within 1–3 business days. Business days are Monday to Friday, excluding UK bank holidays. Delivery estimates are not guaranteed unless a guaranteed delivery service has been expressly offered, selected and confirmed.

Yes — once your order has been dispatched we send a shipping confirmation email with tracking information where it is available. Tracking updates are provided by the courier, so please allow a little time for the first scan to appear.

Not if you are a UK customer. Because we ship from a UK warehouse, UK orders carry no import duties, no customs clearance fees and no unexpected import charges on delivery. For UK customers, prices include VAT where VAT is applicable, unless stated otherwise.

For any international order, import duty, local tax, customs clearance and brokerage fees are set by the destination country and are the customer's responsibility unless we expressly state otherwise at checkout.

Contact us at support@reddotsight.co.uk as soon as possible with your order number. If the order has not yet been processed or dispatched we will try to cancel it and issue a refund. If it has already been dispatched, you will need to follow the returns process instead.

For UK consumer orders placed online you may normally also have the right to cancel within 14 days of receiving the goods, unless an exception applies. See our Refund Policy for the detail.

First check with anyone else at the address, look in any safe place the courier may have used, ask immediate neighbours, and check with your local delivery office — parcels marked delivered are very often one of these.

If it still has not turned up, email support@reddotsight.co.uk with your order number and tracking details. We may need to investigate with the courier before issuing a replacement or refund, and we may ask you to confirm in writing that the parcel was not received.

We offer a 30-day return window from the date your order is delivered. The item needs to come back unused and in resaleable condition, complete with all original packaging, manuals, mounts, screws, tools, lens cloths, batteries, accessories, inserts and labels, and free from installation or mounting marks.

Please contact us before sending anything back — returns sent without authorisation may be delayed, refused or returned to sender. The full terms are in our Refund Policy.

For a change-of-mind return, the customer is responsible for return postage, and you remain responsible for the item until it reaches us — we strongly recommend a tracked and insured service.

Where an item is faulty, incorrect, or was damaged before delivery, we will provide return instructions and, where required, cover reasonable return postage.

Not as a change-of-mind return. Optics that have been used, fitted, mounted, zeroed, torqued, adjusted, scratched, marked or altered are excluded, as are products with mounting or screw marks and products returned with packaging, manuals, seals or accessories missing.

This does not affect your statutory rights if an item turns out to be faulty or not as described.

Refunds are normally processed within 14 days of us receiving the returned item, or earlier where required by law, and are issued to the original payment method after inspection. Your bank or payment provider may add a few days on top before the money appears.

Many do. Some products are supplied with a manufacturer warranty, and the terms vary by brand, product and region — where a warranty applies to a specific optic it is noted on that product page.

Manufacturer warranties are provided by the manufacturer, not by Red Dot Sight UK, unless we expressly state otherwise. We will help by providing order details and pointing you at the right warranty process, but we do not control the manufacturer's decision or timescale. Damage from misuse, incorrect installation, unauthorised modification, accidental damage, neglect, normal wear and tear or improper mounting may not be covered.

Warranty claims are separate from our 30-day returns policy and do not affect your statutory rights.

Email support@reddotsight.co.uk with your order number, a clear description of the problem and photographs of the parcel, the packaging, the item and the shipping label — plus a short video where the fault is electronic or related to the illumination.

Where possible, please report delivery damage within 48 hours of delivery so we can raise it quickly with the carrier. That 48-hour request does not remove your statutory rights.

Email support@reddotsight.co.uk. Please include your order number if your question is about an existing order — it lets us answer first time instead of asking you for it.

If you are choosing between two optics, tell us what you are mounting it to and how you shoot, and we will give you a straight answer.