US Optics ER-25 – Your best bet for Enhanced Magnification and Customization

The product line and manufacturing strategies of US Optics have undergone quite a number of changes in recent times. The basic idea behind these changes was to enhance competence and diminish the waiting time for custom builds by ensuring availability of famed scopes with multiple dealers. As a result of this the ERGO models have been taken off the list and the standard parallax adjustments have become TPAL.

The amended lexicon

The product line transformations have lead to new designations for scopes. The scopes are currently labelled SR (Short Range), MR (Medium Range), LR (Long Range) and ER (Extended Range) in accordance with the magnification capabilities and type of use. Even with all these changes, the company enables the user to build a scope of his or her liking by ensuring the availability of reticles, windage and elevation knobs in MOA (Minute of Angle), Millards (MRad) and Inch per Hundred Yard (IPHY) options.

Components and Characteristics

  • Objective: The SN – 3 5-25x has been rechristened as ER-25 and 58mm is the only objective size available. For a lucid and high clarity image, the objective lens of the ER-25 is built to be very large thus ensuring the transmission of maximum amount of light through the rifle scope.
  • Main tube: The earlier 30 and 35 mm main tubes are not available anymore. The standard tube diameter currently is 34mm. Though the enhancement in tube size does not aid in transmission of light, it increases the space for erector travel and also ensures that the scope has augmented elevation and windage options for you to dial. This feature is particularly useful for long range and ultra long range shooters.
  • EREK elevation: Through the Erector Repositioning Elevation Knob or EREK, the user has access to a wide range of travel for dialling elevation. Setting up can be little tricky initially but post set up; the knob is an excellent asset to the user. It is pretty understated and offers a great level of elevation per single revolution. The US Optics’s ER-25 has about 100 MOA or travel.
  • Internal Anti Cant Device: To ensure that the levelling of rifle is done quickly and effortlessly, US Optics has come with a unique component called the Internal ACD. The ACD consists of a bubble level which resides within the main tube and is observable through the sight picture.
  • Reticle: The reticle scales perfectly with the magnification as it is located on the focal plane. This ensures that the crosshairs of the reticle remain constant. While there is an array of reticles available for selection (MRad, MOA and IPHY), the CMG MOA is ideal for Minute of Angle scopes and MIL Scale MPR is perfect for MRADs.


  • Reticle Illumination: The illumination of the reticle is regulated via 3 distinct push buttons. The on and off and the up / down button for regulating the strength of illumination by way of enhancing or reducing it. The digital Illuminaton is available in 3 standard colors. Red, Blue and Green. The setting is preserved even illumination is turned off and back on.
  • Quick focus: The eye piece of the scope has been designed to ensure quick focus. The process is made quite simple with just an in or out turn of the adjustment. The result is a well defined and clear image.
  • US #3 windage knob: The ER-25 is equipped with a US #3 windage knob that is marked to specify the direction (Left and right) of dialling. The knob has a solid grip and is easy to operate as the clicks are identifiable by means of sound and touch. Zeroing the knob is just as simple. By loosening the allen and placing it on zero and then tightening the allen, you can zero the knob in seconds. The knob also comes with a windage stop and can be placed on either side of the scope depending on your preference.
  • Magnification ring: The ring of the ER-25 is made such that the surface offers a great grip. Even though the ring is quite easy to twist, it has to be done deliberately. Accidental pushes or bumps will not budge it from its position. It takes about ¾ of a turn to move from the lowest level of magnification which is 5X to the highest which is 25X. The ring is clearly marked to show the level of power the user is currently on.
  • Turret Adjustable Parallax (TPAL): The Parallax regulation knob’s surface is similar to the windage and magnification ring and is designed to enhance grip. The knob which is present on the turret housing can be placed on either side of the scope in accordance with your preference.
  • Specs: The scope has a length of about 18” and weighs 2.5 lbs. It has an eye relief of about 3.5” and a magnification range of 5X – 25X. Its FOV is 16.6 feet at 100 yards (5X) and 5.3 feet at 100 yards (25X). Its area of travel or MOA is 100 and the entire scope body is made of 6061 – T6 Aircraft Aluminum.