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Questions & Answers
I've got a FSB; do I need a mount to clear the scope over it? Expert Answer

You will need a riser mount for the Trijicon ACOG 4x32mm Rifle Scopes w/TA51 Mount to clear am FSB. The mount at the link below should work.
https://www.opticsplanet.com/american-defense-manufacturing-ad-b3-c-cantilever-acog-base.html

by Hunter, Gear Expert, October 17, 2023
Can you mount a small red dot on top of it? Expert Answer

Yes, you would be able to purchase and install the Trijicon RMR Mount for ACOG Scopes with bosses (linked below) to this Trijicon ACOG TA31, and it would allow you to mount an optic that uses the Trijicon RMR optic footprint.
https://www.opticsplanet.com/trijicon-rmr-mount-for-acog-scopes-with-bosses.html

by Ethan, Gear Expert, August 11, 2022
Customer Reviews
Helpful Positive Review Best AR optic IMHO by DoItAll, Verified Owner, March 29, 2023
Dating back to my time in service, I will say that IMHO, the ACOG TA31 4x32mm rifle scope is the best optic for an AR for anything close quarters to 300 yards. I've tried a half dozen sights from major players in the optics world with military contra...
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6/6 found this helpful
Helpful Positive Review worth every penny by Sneadoh, January 1, 2023
After coming back to civilian life full time, I thought I’d give every optic I could find a turn to see how they’d run. Everything within the price point of an ACOG fell short at something and certain things excelled! Tango 6T’s glass or Burris’s win...
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8/8 found this helpful
Helpful Positive Review Have ACOG, Will Travel by Yo Payly, February 15, 2024
I've used these in every environment we could that has destroyed everything else. Minus 30º to 120º in the shade. Salt water, sand storms, jungles, and mountains. Fell out of aircraft, bounced around in offroad vehicles, and limousines in cities. I...
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2/2 found this helpful
Helpful Positive Review Fantastic optic BUT.... by D, Verified Owner, March 6, 2024
Excellent optic! unfortunately eye relief is too short for using properly with my helmet and ear pro, and NVG with piggyback RMR, so will go with the 3.5x. I've used both, and the weight is almost the same in real terms...I like the size of the 4x be...
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1/1 found this helpful
Helpful Positive Review Trijicon ACOG 4x 32 scope by Keith, May 5, 2022
I purchased this scope for my new Scar 16s NRCH. As this is a battle tested scope, I was eager to test it out. I was extremely pleased with the eyes wide open experience. Extremely clear optic with red crosshairs, designed for the 223 rifle. I sight...
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15/21 found this helpful
Helpful Positive Review Reputation precedes by Dom, July 22, 2023
22July23; I just recieved a 4x32 with the amber chevron, and it arrived on time and in perfect condition. This ACOG is absolutely flawless! A shout-out to Optics Planet's customer service department; they replied to all my emails and answered all my ...
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1/1 found this helpful
Read All 15 Reviews
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Product Info for Trijicon ACOG 4x32mm Rifle Scopes w/TA51 Mount

The Trijicon ACOG TA31 4x32mm Rifle Scope with TA51 Mount is an innovative, enhanced version of the 4x32 Rifle Scope. Built for the most demanding user, the Trijicon ACOG TA31 4x32 Rifle Scope provides robust engineering, precise performance and advanced capability. This Rifle Scope from Trijicon was initially bundled with the TA51 mount, allowing the end user to mount the scope anywhere that has a flattop rail. The patented ACOG reticle is easy to use - just move the reticle subtensions with your mouse, select the necessary range, and the red dot will always be there - unless you choose to manually rotate the reticle. Once you have adjusted the reticle to meet your needs, simply rotate the reticle to your desired location and release the tension. The reticle will resync automatically when any light source is shone on it.image

Specifications for Trijicon ACOG 4x32mm Rifle Scopes w/TA51 Mount:

Manufacturer: Trijicon
Objective Lens Diameter: 32 mm
Magnification: 4 x
Tube Diameter: 32 mm
Exit Pupil: 8 mm
Finish: Matte
Field of View, Linear: 36.8 ft at 100 yds
Eye Relief: 1.5 in
Adjustment Type: MOA
Parallax: Fixed
Illumination Type: Fiber Optics/Tritium
Optical Coating: Multi-Coated
Water Resistance Level: Waterproof
Additional Features: ACOG TA31
Country of Origin: USA

Features of Trijicon ACOG 4x32mm Rifle Scopes w/TA51 Mount

  • Always On, always ready batteryfree, featuring a tritium/fiber opticilluminated reticle that automatically adjusts the brightness based on available light.
  • Outstanding Clarity, the quality of the glass and multicoated lenses maximizes lightgathering capabilities and clear field of view with zero distortion.
  • Rugged aluminum alloy housing
  • Fixedpower design allows for minimal moving parts to create a nearly indestructible sighting system.
  • Combat proven, no other magnified optic has been used more in combat than the ACOG.
  • Shock resistant, proven to withstand recoil from a .22LR to a .50BMG and everything in between.
  • Waterproof, exceptional waterproof performance.
  • Dry nitrogenfilled to eliminate fogging and tested to perform in both extreme cold and heat.
  • Both Eyes Open design, can be used as a CQB sight when shooting both eyes open using the Bindon Aiming Concept (BAC) feature.
  • BDC Chevron Reticle
  • Red illuminated chevron reticle featuring ballistic drop compensation (BDC) for .223 / 5.56 caliber

Package Contents:

  • Trijicon ACOG 4x32mm Rifle Scopes w/TA51 Mount

Trijicon ACOG 4x32mm Rifle Scopes w/TA51 Mount Orderable Models

List of Orderable Models

Trijicon ACOG TA31 4x32mm Rifle Scope, Sniper Gray, Illum Red Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100308 , MPN: 100308 , UPC: 719307307223 , Code: TJ-RS-ATA31-100308
Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Illum Green Horseshoe/Dot .223 / 5.56x45mm Reticle, MOA Adjustment, 100367 , MPN: 100367 , UPC: 719307307780 , Code: TJ-RS-ATA31-100367
Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Green Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100379 , MPN: 100379 , UPC: 719307307964 , Code: TJ-RS-ATA31-100379
Trijicon Limited Edition ACOG Three Color Tiger Camouflage 4x32mm Rifle Scopes w/TA51 Mount, Dual Illuminated Red Chevron Reticle, Three Color Tiger Camouflage, 100763 , MPN: 100763 , UPC: 719307619340 , Code: TJ-RS-ATA31-100763
Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Red Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, TA31F , MPN: TA31F , UPC: 719307300095 , Code: TJ-RS-ATA31-TA31F
Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Illum Red Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100309 , MPN: 100309 , UPC: 719307307230 , Code: TJ-RS-ATA31-100309
Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Illum Green Horseshoe/Dot .223 / 5.56x45mm Reticle, MOA Adjustment, 100366 , MPN: 100366 , UPC: 719307307773 , Code: TJ-RS-ATA31-100366
Trijicon ACOG TA31 4x32mm Rifle Scope, Sniper Gray, Green Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100378 , MPN: 100378 , UPC: 719307307957 , Code: TJ-RS-ATA31-100378
Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Illum Green Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100312 , MPN: 100312 , UPC: 719307307261 , Code: TJ-RS-ATA31-100312
Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Red Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100372 , MPN: 100372 , UPC: 719307307902 , Code: TJ-RS-ATA31-100372
DEMO, Trijicon Limited Edition ACOG Three Color Tiger Camouflage 4x32mm Rifle Scopes w/TA51 Mount, Dual Illuminated Red Chevron Reticle, Three Color Tiger Camouflage, 100763 , MPN: 100763-DEMO , Code: TJ-RS-ATA31-100763-DEMO
Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Green Chevron 5.56x45mm M193 / 55 Grain Reticle, MOA Adjustment, 100290 , MPN: 100290 , UPC: 719307306868 , Code: TJ-RS-ATA31-100290
Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Red Chevron 5.56x45mm M193 / 55 Grain Reticle, MOA Adjustment, 100288 , MPN: 100288 , UPC: 719307306882 , Code: TJ-RS-ATA31-100288
Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Green Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100380 , MPN: 100380 , UPC: 719307307971 , Code: TJ-RS-ATA31-100380
Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Illum Green Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100313 , MPN: 100313 , UPC: 719307307278 , Code: TJ-RS-ATA31-100313
Trijicon ACOG TA31 4x32mm Rifle Scope, Sniper Gray, Red Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100370 , MPN: 100370 , UPC: 719307307889 , Code: TJ-RS-ATA31-100370
Trijicon ACOG TA31 4x32mm Rifle Scope, Sniper Gray, Illum Green Horseshoe/Dot .223 / 5.56x45mm Reticle, MOA Adjustment, 100365 , MPN: 100365 , UPC: 719307307766 , Code: TJ-RS-ATA31-100365
Trijicon ACOG TA31 4x32mm Rifle Scope, Sniper Gray, Illum Green Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100311 , MPN: 100311 , UPC: 719307307254 , Code: TJ-RS-ATA31-100311
Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Illum Red Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100310 , MPN: 100310 , UPC: 719307307247 , Code: TJ-RS-ATA31-100310
Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Amber Chevron 5.56x45mm M193 / 55 Grain Reticle, MOA Adjustment, 100289 , MPN: 100289 , UPC: 719307306875 , Code: TJ-RS-ATA31-100289
Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Amber Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100216 , MPN: 100216 , UPC: 719307301313 , Code: TJ-RS-ATA31-TA31F-A

Trijicon ACOG 4x32mm Rifle Scopes w/TA51 Mount Unavailable & Discontinued Models

List of Unorderable Models

DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Illum Red Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100309 , MPN: 100309-DEMO , Code: TJ-RS-ATA31-100309-DEMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Green Chevron 5.56x45mm M193 / 55 Grain Reticle, MOA Adjustment, 100290-DEMO , MPN: 100290-DEMO , Code: TJ-RS-ATA31-100290-DEMO
OPEN BOX, DEALER DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Red Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100371-DMO , MPN: TA31-C-100371-DMO , Code: TJ-RS-ATA31-TA31-C-100371-DMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Amber Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100216 , MPN: 100216-DEMO , Code: TJ-RS-ATA31-TA31F-A-DEMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Red Chevron 5.56x45mm M193 / 55 Grain Reticle, MOA Adjustment, TA31F-DEMO , MPN: TA31F-DEMO , Code: TJ-RS-ATA31-TA31F-DEMO
OPEN BOX, DEALER DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Green Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100380-DMO , MPN: TA31-C-100380-DMO , Code: TJ-RS-ATA31-TA31-C-100380-DMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Black, Red Chevron 5.56x45mm M193 / 55 Grain Reticle, MOA Adjustment, 100288-DEMO , MPN: 100288-DEMO , Code: TJ-RS-ATA31-100288-DEMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Red Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100371 , MPN: 100371-DEMO , Code: TJ-RS-ATA31-100371-DEMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Sniper Gray, Red Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100370 , MPN: 100370-DEMO , Code: TJ-RS-ATA31-100370-DEMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Illum Red Chevron .223 / 5.56x45mm Reticle, MOA Adjustment, 100310 , MPN: 100310-DEMO , Code: TJ-RS-ATA31-100310-DEMO
OPEN BOX, DEALER DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Sniper Gray, Green Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100378-DMO , MPN: TA31-C-100378-DMO , Code: TJ-RS-ATA31-TA31-C-100378-DMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Green Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100380 , MPN: 100380-DEMO , Code: TJ-RS-ATA31-100380-DEMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Sniper Gray, Green Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100378 , MPN: 100378-DEMO , Code: TJ-RS-ATA31-100378-DEMO
Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Red Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100371 , MPN: 100371 , UPC: 719307307896 , Code: TJ-RS-ATA31-100371
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, OD Green, Green Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100379 , MPN: 100379-DEMO , Code: TJ-RS-ATA31-100379-DEMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Illum Green Horseshoe/Dot .223 / 5.56x45mm Reticle, MOA Adjustment, 100367 , MPN: 100367-DEMO , Code: TJ-RS-ATA31-100367-DEMO
DEMO, Trijicon ACOG TA31 4x32mm Rifle Scope, Flat Dark Earth, Red Crosshair .223 / 5.56x45mm Reticle, MOA Adjustment, 100372 , MPN: 100372-DEMO , Code: TJ-RS-ATA31-100372-DEMO
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