Scope mount#Mounts for compact sights

File:SSG 82 1.jpg fitted with a 4×32 Zeiss Jena sight, note the integral rail interface on the scope tube]]

File:PSG-1 rifle 2014 noBG.jpg]]

File:PSL Dragunov 7.62 mm Sniper Rifle - Telescopic sight.jpg scope with integral side-mount on a Romanian PSL rifle]]

Among scopes for rail mounts, the 22.5-degree V-shaped Zeiss rail is the most prevalent standard. It was introduced in 1990. After the patent expired in 2008, compatible scopes have been offered from manufacturers such as Blaser,[https://rifles-scopes-expert.co.uk/scope-comparisons/blaser-infinity-2-8-20x50-ic-vs-swarovski-z8i-2-16x50/ Blaser Infinity 2.8-20x50 IC vs Swarovski Z8i 2-16x50 – Rifles Scopes Expert] Every Blaser [scope] comes with a Zeiss ZM/VM mounting rail [...] Leica, Minox, Meopta, Nikon,[https://www.nikon.ee/imported/images/web/EU/learn-and-explore/brochures-leaflets/sport-optics/nikon_sport_optics_hunting_2017_en--original.pdf Nikon Sport Optics & Hunting Catalogue 2017] "Rail mount models (Zeiss Inner Rail Standard) are available (1-4x24 IL ZR and 2.5-10x50SF IL ZR" Noblex (formerly Docter[https://optics-info.com/docter-to-noblex/ Docter to Noblex – Optics info]), Schmidt & Bender[http://schmidtbender.hu/wp-content/uploads/2016/05/Catalog-2016-ENG.pdf Schmidt & Bender – Main catalog 2016] and Steiner.[https://www.steiner-optics.com/sites/default/files/manuals/Nighthunter%20Xtreme%20Riflescope%20Instruction%20Manual.pdf Nighthunter Xtreme Riflescope Instruction Manual] "Rail models work with standard rail bases for “Z" or Zeiss rails." It has therefore, in some sense, become the de facto industry standard for scope mounting rails. The system has so far seen most use on the European high end market.[https://optics-info.com/zeiss-zm-vm-rifle-scope-mounting-rail/ Zeiss ZM / VM Rifle Scope mounting rail – Optics info]

The Swarovski SR rail (patented in 2002,[https://patents.google.com/patent/AT480748T/en Patent AT480748T] Application filed 9 June 2002 by Swarovski Optik][https://patents.google.com/patent/US6901692B2/en Patent US6901692B2] Application granted 7 June 2005][https://patents.google.com/patent/DE50214644D1/en Patent DE50214644D1] Application granted 21 October 2010] introduced in 2005[http://www.hoferwaffen.com/images/optics/Swarowski_en.pdf Swarovski catalog October 2005] The Swarovski SR rail is also used by Kahles, a Swarovski subsidiary.[https://huntforever.org/2016/12/05/scopes-and-mounting-systems/ Scopes and Mounting Systems | Hunt Forever]) has a flat rail with many "teeth" as recoil lugs, and is only offered on scopes from Swarovski and its subsidiary Kahles. It separates itself from the Zeiss rail in that it is not neither stepless nor self-centering.

A former competing standard was the halv-circle shaped Schmidt & Bender Convex rail also introduced in 2005. Schmidt & Bender after a few years changed to the Zeiss rail standard. In contrast to the Zeiss and Swarovski systems, the S&B Convex rail had the possibility to add a cant to the scope when mounting, such that the reticle is not horizontal to the ground.[https://www.optics-trade.eu/download/Schmidt-Bender/Catalog%20SCHMIDT%20&%20BENDER%20Hunting%20-%20Optics%20Trade%20-%202011.pdf Schmidt & Bender catalogue] "The convex hollow rail. Our hollow rail with a convex outer surface, offered on all Zenith models, is distinguished by elegant lines, and allows the use of reliable slide-in mount fasteners. This innovative rail also makes it possible to tilt the scope up to 1° to the left or to the right."

There is an older European system with an upside-down V-shape (70 degrees).{{Cite web|title=LM rail Mounts – Optics-Trade|url=https://www.optics-trade.eu/us/mounts/shopby/ring_diameter-lm_rail.html|access-date=2021-01-04|website=United States|language=en}} This system has little widespread use today. The advantage of this system was that it at one time was offered by most European scope manufacturers, but the disadvantage was that the rail had to be drilled for a screw each time the eye relief was to be adjusted.{{Cite web|title=LM rail and mounting solutions {{!}} Optics Trade Debates – YouTube|url=https://www.youtube.com/watch?v=rGcMD7ucTC0|access-date=2021-01-04|website=www.youtube.com}} All new standards for rail mounts have addressed this issue.

File:Large SMG00029515.jpg

File:Pythons2.jpg revolvers, one (above) with barrel-mounted scope]]

File:East Tennessee Crossing - Battle of Bean Station Re-enactment - NARA - 7718106.jpg sharpshooter aiming a Whitworth rifle with a ring-mounted scope, secured by clamping onto the gunstock]]

File:8,6_TKIV_2000_Lippujuhlan_päivä_2014_2.JPG.]]

Ring mounts usually consist of a base attached to the firearm and rings (usually two) attached to the sight. The rings are usually made of steel or aluminum. Common diameters on ring mounts are 25.4 mm (1 inch), 26 mm, 30 mm and 34 mm. There are big differences in the strength and ability of sustained precision on different assemblies. With weak cartridges such as .22 LR applied in light-use scenarios, a pair of skinny aluminium rings may work well, while firearms with very powerful recoil often combined with a heavy sight may require steel rings or thicker aluminum rings with recoil lugs to be used.

Scopes for ring mounts are available in many different sizes. The most common ones are:

• 1 inch (25.4 mm)
• 30 mm
• 34 mm

Some less common standards are:

• {{convert|3/4|in|mm}}
• {{convert|7/8|in|mm}}
• 26 mm – Some older European scopes
• 35 mm – Some IOR, Vortex and Leupold models
• 36 mm – Some Zeiss and Hensoldt models
• 40 mm – Some IOR models and Swarovski dS

For a ring assembly to grip evenly, it is important that the scope rings are circular and coaxial with the scope tube. On ring mounts that grip unevenly, the ring mount can be lapped to prevent uneven pressure when mounting.[https://www.rifleshootermag.com/editorial/how-to-lap-scope-rings/83774 RifleShooter – How to Lap Scope Rings] One scopes made for ring mounts, it is not uncommon to get ring marks when mounting the rings.

There are insert rings on the market which allows for mounting a scope inside a ring mount of a larger diameter. An example could be to mount a scope with a 1-inch (25.4 mm) tube in a 30 mm mount using a plastic insert.

There are also special ring mounts in the market with circularly shaped ring inserts made to provide stress free mounting without lapping, with Burris Signature Rings and Sako Optilock Rings as two well-known examples. Burris Signature was introduced in 1995.[https://www.burrisoptics.com/history History | Burris Optics] A patent was applied for in 1994, and was granted in 1995.[https://patents.google.com/patent/US5433010A US5433010A – Self aligning optical gun sight mount with eccentric adjustment capabilities – Google Patents] Sako Optilock has been sold since some time in the early 2000s.[http://www.silhouetten.org/Waffen/Visierungen/einstell.htm Internationaler Silhouettenclub – Visiereinstellungen]{{Clarify|date=January 2021}} The trade name Optilock was registered in the US in December 1997, and has been marketed in the US since December 2001.[http://tmsearch.uspto.gov/bin/showfield?f=doc&state=4805:ltv2rw.2.10 Trademark Electronic Search System (TESS) – 77509718] In 2000, Sako was sold to Beretta Holding.{{cite web|title=Suomalainen asetehdas löysi isännän Italiasta – "Olemme outo osakkeenomistaja"|url=https://www.talouselama.fi/uutiset/suomalainen-asetehdas-loysi-isannan-italiasta-olemme-outo-osakkeenomistaja/b1ea9aa1-643a-355b-b7ba-8a505567512f|last=Lähteenmäki|first=Pekka|date=28 December 2016|access-date=11 May 2018}} In 2002, Burris was also sold to Beretta Holding, and thus Burris and Sako got the same owners. Burris' original patent for the rings with the circular insertes was considered to have expired in 2014, and as of 2020 is listed as "definitely expired".

In 2015, XTR Signature Rings was launched as a further development of the Burris Signature series. The XTR variant differs in that it has two circular cavities per ring assembly versus one. A patent for the XTR Signature Rings was applied for in 2016, and was granted to Burris in 2019.[https://patents.google.com/patent/US10415934B2/en?oq=10415934 US10415934B2 – Self-aligning optical sight mount – Google Patents]

File:Aimpoint Acro C2 and Picatinny riser with Acro rail.jpg Acro C2 reflex sight laying on its side. Right: Acro rail on a Picatinny riser.]]

File:Acro style dovetail rail dimensions.png

Many reflex sights (e.g. red dot sights) and holographic sights have proprietary mounts.[https://optics-info.com/footprints-on-red-dot-sights/ Footprints/Mounting Standards on Red Dot Sights – Optics info]

• Aimpoint Acro rail: A dovetail rail for attaching a sight via a clamping mechanism, and with a 4 mm{{cite web|access-date=2022-10-16|date=2022-08-24|first=Andraž|language=en-GB|surname=Gradišnik|title=Aimpoint Acro C-2 Footprint|url=https://www.optics-trade.eu/blog/aimpoint-acro-c-2-footprint/|work=Optics Trade Blog}} wide straight recoil lug groove. The dovetail is approximately 16.5 mm wide, and is radiused so as not to have any sharp edges. The mount is compact enough to be used on pistols, as well as rifles and shotguns. Launched in 2019 together with the sights Aimpoint Acro P-1 and C-1.{{cite web|url=https://www.optics-trade.eu/us/mounts/red-dot-sights-mounts/aimpoint-acro-mounts.html|title=Aimpoint ACRO Mounts – Optics-Trade|work=United States|language=en|access-date=5 November 2022}} Also used on Aimpoint Acro C-2 and P-2, as well as Steiner MPS.
• Aimpoint Micro standard: First introduced in 2007{{cite web|url=https://aimpoint.us/history/|title=History|work=aimpoint.us|access-date=5 November 2022}} on the small tube sight variants of Aimpoint, but today used by other manufacturers as well. Popular on rifles and shotguns, but not on handguns due to its size. The mounting standard uses four screws and one cross slot acting as a recoil lug. Used on red dot sights such as Aimpoint Micro, Vortex Crossfire, Sig Sauer Romeo 4 & 5, and some Holosun Paralow variants.
• Aimpoint CompM4 mount: Launched in 2007{{cite web|url=https://gunivore.com/accessories/aimpoint-comp-m4-sight-review/|title=Aimpoint Comp M4 Sight|last=M|first=Sam|work=Gunivore|language=en-US|date=21 April 2016|access-date=5 November 2022}} with the Aimpoint CompM4 sight. The sight is attached to the mount via two M5 screws from the underside, and the mount has a transverse groove acting as a recoil lug. The Aimpoint Comp line was launched in 1993. The predecessor of the CompM4, CompM2, had a 30 mm ring mount and was introduced in the American military in 2000. Some manufacturers have copied the M4 mount system, but it has mainly been used by Aimpoint.[https://www.youtube.com/watch?v=_wJqlH_jwsU Aimpoint Comp M4 review]{{citation needed|reason=Content from websites whose content is largely user-generated is generally unacceptable, per WP:RS#Self-published_sources_(online_and_paper)|date=March 2021}}
• C-More standard: A mounting standard introduced by C-More Sights. Uses two screws and two circular notches acting as recoil lugs. Used on red dot sights such as Delta Optical MiniDot, Kahles Helia, Vortex Razor and Sig Sauer Romeo3.
• Docter/Noblex standard: The mounting pattern which through the 2010s was used by the largest number of manufacturers, perhaps due to the wide range of aftermarket mounts available. The mounting standard uses two screws and four circular notches acting as recoil lugs. Used on red dot sights such as Docter/Noblex sights, Burris Fastfire, Vortex Viper, Leica Tempus, etc.
• Shield standard: A proprietary standard used by Shield Sights. Similar in shape to the Noblex/Docter footprint, but with other dimensions. In addition to the Shield red dot sights, it is also used on the Leupold Delta Point Pro.
• Trijicon RMR/SRO-standard: Has two screw holes, and two shallow circular notches acting as recoil lugs. Mainly used on the Trijicon RMR and SRO red dot sights, as well as on some Holosun sights.
• Other: Some notable red dot sights which have unique footprints not compatible with any of the above are Sig Sauer Romeo 1, Holosun Paralow 403A, Holosun 509T and Swampfox Kraken MRDS. There also exists reflex sights for ring mounts (e.g. Aimpoint CompM2 with a 30 mm tube) or with an integrated Picatinny base.

By bases, is usually meant an interconnecting part between the scope and the firearm. For example, a base may have a picatinny attachment on the underside, while the upper side may have either a ring (e.g. 30 mm) or rail mounting (e.g. Zeiss rail). On some assemblies, the upper and lower parts of the base are separate parts that must be screwed together and fastened to a specified torque.[https://www.tactec.com/scope-rifle-torque-specs-database/ Scope & Rifle Torque Specs Database | Tactec] A base can thus sometimes constitute a complete scope mount assembly, but is most often used to refer to the lower part of a two-part scope mount assembly.

The firearm interface which sits on the firearm and to which the scope mount is attached is often called the base or rail.

Some types of bases are:

;Standard mounts:

• Picatinny rail: Standardized slot distances.
• Weaver rail: Varying width between the slots.

Picatinny.svg|Metric dimensions on a Picatinny rail.

Scope mount on Gamo airgun.jpg|Weaver rail on an air gun.

;Proprietary and brand specific mounts:

• Claw mount. Several types, for example Suhl Claw Mounts,[https://www.optics-trade.eu/int/mounts/detachable-mounts/suhl-claw-mounts.html Suhl Claw Scope Mounts – Optics-Trade] Ziegler ZP mount, and others.
• Pivot mount. Several types, for example EAW, MAKlick, Steyr Luxus, and others.[https://www.optics-trade.eu/int/mounts/detachable-mounts/pivot-mounts.html Pivot Scope Mounts – Optics-Trade]
• Aimpoint Micro, also used by other red dot manufacturers.[https://www.optics-trade.eu/en/mounts/aimpoint-micro-mounts.html Aimpoint Micro mounts selection] (Not compatible with Aimpoint Comp or the Aimpoint ACRO mounting standards. See Red dot sight#Mounting types for more red dot mounting standards).
• Blaser saddle mount{{cite web|last1=De Vries III|first1=George|title=Blaser R93 Rifles|url=http://www.chuckhawks.com/blaser_R93_rifles.htm|website=chuckhawks.com|accessdate=26 February 2017}}
• Contessa 12 mm "Euro rail" mount[https://www.optics-trade.eu/int/mounts/shopby/manufacturer-contessa.html Contessa 12 mm rails – Contessa Mounts – Optics-Trade][https://www.alanrhone.com/products-contessa-12mm-rail-working.html Alan Rhone Ltd – Contessa | How the 12mm Euro Rail Works]
• Browning X-Lock[https://www.browning.com/news/tech-terms/x-lock.html X-Lock – Browning North America]
• Double dovetail, which is rotated and tapped into place.[https://www.youtube.com/watch?v=bpiSEcZO5uQ ] Installing Standard and Double Dovetail Rings – YouTube] Several types, for example the Leupold Dual Dovetail[https://www.leupold.com/product-series/dual-dovetail-mounting-systems Dual Dovetail Scope Mounting Kits | Leupold]
• Mauser M03 Double Square Mount[https://www.youtube.com/watch?v=d_81OXt_vX0 Studio FortHjort – Tilpasning av Mauser M03 montasje – YouTube Video of fitting the Mauser M03 Scope Mount on YouTube] (Norwegian)[http://mauserm03blog.blogspot.com/2017/05/mauser-m03-installing-riflescopes-to.html Mauser M03 Blog: Mauser M03 – Installing Riflescopes to Double Square Mounts][https://www.shootinguk.co.uk/reviews/rifle/mauser-m03-rifle-review Mauser M03 rifle review – Shooting UK]
• Picatinny-against-picatinny (Burris Eliminator[https://iamhunter.net/into-the-wild/the-armoury/tutorials/mounting-the-burris-eliminator-iii/ Mounting the Burris Eliminator III – I Am Hunter])
• Pulsar type rail mount. Has some visual similarities with the Zeiss rail, but is incompatible due to a wider base and steeper angle.{{citation needed|date=January 2021}}
• Redfield type[https://www.nwaonline.com/news/2020/jul/12/rings-and-bases/ Rings and bases: Rifle accuracy starts with the scope mounts] with windage adjustable mount, also known Redfield Standard Junior. Similar concepts are made by other manufacturers, e.g. "Leupold standard", "Burris TU/SU". Also manufactured by Weaver. Specifications can vary between manufacturers.{{Citation needed|date=January 2021}}
• Ruger integral type (used on Ruger No. 1,[https://warnescopemounts.com/product-category/ruger-mounts/ Ruger Mounts Archives – Warne Scope Mounts] "Model specific fits (dovetail only) for Ruger #1, M77 centerfire, Mini-14 Ranch, Mini-30 Ranch, Redhawk, Super Blackhawk, Single-Six, Super Redhawk and 77/17, 77/22, 77/357, 77/44" M77,[https://www.americanrifleman.org/articles/2018/11/16/the-ruger-model-77-rifle-turns-50/ American Rifleman | The Ruger Model 77 Rifle Turns 50] Gunsite Scout,[https://www.sporting-rifle.com/reviews/ruger-scout-review/ Ruger Scout Review | Sporting Rifle magazine] the Ranch series of the Mini-14[https://www.americanrifleman.org/articles/2015/4/22/ruger-mini-14-tactical-in-300-aac-blackout/ American Rifleman | Ruger Mini-14 Tactical in 300 AAC Blackout] and Mini-30, Deerfield carbine,{{citation needed|date=January 2021}} Model 96 (.44 Magnum only)[https://ruger-docs.s3.amazonaws.com/_manuals/model96.pdf Model 96 Instruction Manual – model96.pdf] and Ruger PC carbine.[https://www.policemag.com/338862/tactical-response Tactical Response – Weapons – POLICE Magazine])
• Sako Optilock,[https://www.sako.fi/scope-mounts Scope Mounts | SAKO] either with rings separate from the bases, or with rings as part of the bases. Bases come in various variantes to fit either Sako tapered dovetail rail (available for three different types of action lengths), Tikka straight dovetail (11 mm or 17 mm), Weaver or Picatinny.
• Sako tapered dovetail rail (used on SAKO models Sako 75, Sako 85, L461, L579, S491, M591, L61R, L691, M995 and TRG-S)
• Sauer ISI mount (Sauer 303, and a very few editions of Sauer 202)[https://www.optics-trade.eu/int/mounts/brand-specific-mounts/sauer-isi-rail-mounts.html Sauer ISI Rail Scope Mounts – Optics-Trade]
• Sauer SUM mount (Sauer 404)
• Schultz & Larsen integral Slide & Lock type[https://www.gunmart.net/scopes-and-optics/scopes/scope-mounts/fitting-schultz-larsen-scope-mounts Fitting Schultz & Larsen scope mounts | Scope Mount Reviews | Gun Mart][http://www.greatdanerifles.com/scope-mounts.html Schultz & Larsen | Scope Mounts]
• "STANAG" Claw Mount, used on FN FAL, HK G3, HK33, G3SG/1 and MP5. Most STANAG bases must be used with corresponding STANAG rings, but there are also STANAG bases for scopes with rails.
• Dovetail rail (for example 11 mm, 17 mm or 19 mm). The flank angle varies, and dovetail rail mounts may therefore be regarded as non-standardized, even for a given witdth.
• Trijicon ACOG/VCOG rail

File:MSG 90 rifle museum 2014.png|HK MSG90 with a scope sight mounted in a STANAG claw mount.

On receivers without an integrated attachment for mounting a scope, for example, an integrated Picatinny rail, the base is usually screwed on as a separate part. Such mounts are often model-specific to the firearm, and depend on factors such as the radius of the receiver bridge, the type of screw and the distance between the screw holes. A common fastening method is by screws. These are often metric M3.5x0.6 mm or US #6–48 (⌀ 3.5 mm, 0.53 mm pitch) or #8–40 (⌀ 4.2 mm, 0.64 mm pitch).

Many European assemblies use M3.5 screws, such as SAKO Optilock, Recknagel and original CZ rings. Since #6–48 and M3.5x0.6 have near identical diameters and almost equal pitch, there is a potential for confusion, and upon mixing the wrong screw will enter the threads, but will gradually become tighter to screw until the thread is destroyed. In case of damage, the hole must often be drilled and re-threaded, and M4x0.7 or #8–40 may then be relevant alternatives.

;Remington 700 pattern:

The Remington 700 Short Action (SA) scope base attachment pattern is particularly widespread, and is for example used on models such as:[https://www.optics-trade.eu/int/mounts/shopby/suitable_for_remington-remington_700_sa/ Scope mounts for Remington 700 SA – Optics-Trade]

• Remington Model 722, 40x, 78, 740, 742, 760, 710, 721, 722 and 725
• Mauser M1996 straight pull and Roesser Titan 16
• Mauser SR-97
• Sauer 100, Sauer 101, Mauser M18 (not the M12)
• Bergara B14 LA
• Haenel Jäger 10
• Sabatti Rover LA

The Remington 700 Long Action (LA) naturally has a longer distance between the front and rear screw holes, and therefore continuous scope mount assemblies for the 700 LA do not fit on the 700 SA nor the above-mentioned firearms. However, two-piece scope mounts in general interchange for the mentioned models.

;List of common screw patterns:

Bases with a rounded bottom for mounting on a round receiver bridges should ideally have a slightly smaller radius than the receiver in order to provide two points of contact and give a stable attachment. Conversely, a slightly too large radius on the mount will result in just one point of contact and a less stable attachment.

In the table below, the radius refers to the curvature of the mounting surface on the receiver bridge. The base is often attached with two screws on the front receiver bridge and two screws on the rear receiver bridge, but sometimes with several more screws. The hole distances are measured from center-to-center. Some common hole distances are {{convert|12.7|,|15.37|and|21.84|mm|in|3|abbr=on}} respectively).[https://patents.google.com/patent/US20090133311 US20090133311A1 – Universal scope mounting system – Google Patents]

The two front screws are referred to in the list below as screws 1 and 2, and the front hole spacing is thus referred to as «distance 1–2». In the same way, the rear hole distance is called «distance 3–4». The distance between these is largely determined by the receiver length, and is stated here as «distance 2–3»

File:Left_Side.png

Quick release (QR) can refer to several different variants of scope mounts which can be mounted and disassembled quickly without tools.

{{main|Milliradian#Adjustment range and base tilt}}

In some cases, it may be relevant to add extra inclination to the scope to be able to shoot at longer (or shorter) distance. For example, this is popular for long range shooting, where it is common to use a tilt of 6 mrad (20 MOA). Extra tilt can be achieved several ways, like for example with a tilted Picatiny rail (e.g. 6 mrad tilt), with bases or rings (e.g. 6 mrad tilt) or with special insert rings (e.g. Burris Pos-Align).{{Cite web|url=http://bulletin.accurateshooter.com/2019/06/tough-tactical-rings-with-inserts-best-option-for-prs/|access-date=2021-01-04|website=bulletin.accurateshooter.com|title=Tough Burris Tactical Rings with Inserts — Best Option for PRS? « Daily Bulletin}}

The height of scope sight can be important for the cheek rest support (often called cheek weld) to gain correct eye placement, as well as for calculating ballistics (e.g. a ballistic table). The latter is particularly relevant at very close ranges (e.g. {{convert|15|m|ft|abbr=off|sp=us|disp=sqbr}}), while at longer distances, such as in long range shooting, the scope height has less impact on the ballistic calculations.

The height of a scope sight can be measured in many ways. With regard to ballistic calculations, it is generally only measured from the center of the bore axis to the center of the scope sight (sightline). With regard to cheek support, several methods are used: On firearms with a picatinny rail, the height is measured from the top of the picatinny rail on the firearm. On most other types of bases it is common to measure from the top radius of the receiver bridge.

When the bottom measuring point is determined, the height is then measured up to either the optical center or the bottom of the scope tube, on scopes for ring mounts. The difference between these two measuring methods is distance from the optical center to the bottom of the scope tube, and usually corresponds to half of the tube diameter (e.g. 15 mm on binoculars with a 30 mm tube).

• M-LOK
• Bipod

{{Firearm accessories mounting standards}}

{{Firearms}}

Category:Mechanical standards

Category:Firearm components