The 300 AAC Blackout (300 BLK) has elicited considerable interest in the tactical community. Initially a wildcat cartridge developed by J.D. Jones, the round was further developed when “a military customer wanted a way to be able to shoot .30-caliber bullets from an M4 platform while using normal bolts and magazines, and without losing the full 30-round capacity of standard magazines.”
Full power 115- to 125-grain 300 BLK ammunition matches the ballistics of the 7.62x39mm. Subsonic projectiles provide optimal performance with a suppressor. The 300 BLK ammunition with 220-grain Sierra OTM (open-tip match) bullet vastly outperforms the 9mm MP5-SD.
EOTECH XPS2-300 HWS
Designed with the 300 BLK shooter in mind, the EOTech XPS2-300 Holographic Weapon Sight (HWS) offers a two-dot ballistic drop reticle that allows the shooter to zero either subsonic or supersonic rounds in the same reticle pattern.
The HWS was designed to provide the operator with greatly improved shooting performance by achieving a more rapid reticle-to-target acquisition, unrestricted peripheral vision, and highly accurate shot placement.
The EOTech XPS2-300 is offered in the popular XPS2 platform, which is the shortest and lightest HWS available. The single compact transverse-mounted lithium 123 battery configuration opens up more space on the rail for BUIS or magnifiers.
The original XPS was the result of input from high-level Special Forces operators. Most loved the battery life of the AA and dual CR123 battery HWS models, but wanted a more compact sight. With the introduction of the XPS, EOTech gave operators just that. It provides an extended battery life consistent with the AA alkaline model, but in a body that is shorter and lighter than all previous models. Another plus to the CR123 battery is that most tactical lights/weaponlights use it.
The average battery life of the XPS platform at brightness level 12 is roughly 500 to 600 hours. On all models, battery life is reduced at correspondingly higher settings and increased at lower settings.
The use of lithium batteries extends battery life and allows for operation in more extreme temperatures. Alkaline batteries perform poorly at colder temperatures: they must be above 40 degrees F for best results. Lithium batteries perform well across a much wider temperature range, including below freezing.
To conserve battery power, the XPS sight has an auto shutdown feature that powers the sight down either four or eight hours after you last manipulate the buttons. The reticle retains constant brightness throughout the operational life of the batteries. If the battery is low, the reticle blinks for a few seconds at start-up.
The XPS is installed and removed with a single slotted thumb screw. It is designed to mount to any one-inch Weaver or Picatinny (MILSTD-1913) rail.
Windage and elevation adjustments on the XPS are easily made via separate click adjustment dials on the side of the housing. The adjustment dials are grooved with a slotted screw head. A specialized tool isn’t necessary to make adjustments: a coin or cartridge case works well.
Each click changes the bullet impact point by approximately 0.50 MOA at 100 yards. The adjustment dials are mounted flush with the machined housing to prevent accidental changes in the point of aim.
The EOTech XPS2-300 has 20 normal brightness settings that are easily scrolled through using up and down arrow controls.
EOTech designed its HWS to withstand milspec drop tests and remain fully operational. All the electronics are fully encapsulated in a shock-absorbent resin cavity. According to the company, the HWS are extensively tested during the validation of the product using recoil simulators and a variety of environmental conditions.
The SOF Weapons Program Management Office at NSWC Crane has recently reported (in a SOUM transmitted to SOF on 14 September 2015) some issues with reliability of the HWS at extreme operating temperatures, referred to by the PMO as “Thermal Drift.” The PMO has noted a +/- 4 MOA shift at -40 degrees F and 122 degrees F.
EOTech states on its website: “EOTech’s sights will experience a point of impact shift away from the point of aim when the sight is used at a temperature different from the temperature at which the sight was zeroed. This shift is greater the more extreme the temperature change. For example, when a sight is zeroed at 70°F then acclimated to 50°F, less shift will occur. On the other hand, if zeroed at 70°F, then acclimated to 0°F, more shift could occur. The maximum shift will occur at temperature extremes and could be up to 5 MOA. Therefore, to achieve optimum accuracy, the sight should be re-zeroed whenever the temperature changes markedly from the temperature at which the sight was zeroed.”
Although the HWS was originally stated to be parallax free, all EOTech sights exhibit a varying degree of parallax depending on operating conditions.
HEADS UP DISPLAY
The Heads Up Display (HUD) is constructed of a hardened three-layer, shatter-resistant laminate glass that is 3/16-inch thick. The glass is quite durable. It took several hard hits with a ball-peen hammer to break a test sample. Additional protection for the HUD is provided by a roll-bar type hood.
The optical cavity is sealed and enclosed with a state-of-the art aerospace composite, providing water- and fog-resistant operation. The XPS is submersible to ten feet for 24 hours.
In holography, all the information required to reconstruct the reticle image is recorded everywhere in the HUD display window. If the window is obstructed by mud, snow, rain, or even if the exterior laminated window is shattered, the HWS remains fully operational, with point of aim maintained. This is not possible with any other optic.
The battery cap and latch on the XPS have been replaced with a simple O-ring, tethered cap, which provides better sealing of the battery compartment and prevents the possibility of losing the battery cap.
The battery compartment is separated from the base, so it can hover over the delta ring of AR-15 series rifles. This design lets the user mount the XPS farther forward on the upper receiver rail, freeing up additional rail space for the G33 Magnifier, night vision (on NV compatible models), and laser devices.
The XPS has 20 normal brightness settings that are easily scrolled through using up and down arrow controls. The brightness range of the latest generation HWS, including the EXPS and XPS, has been increased to greatly enhance the low-light performance of the sight. The sight automatically
returns to default setting 12 anytime it is turned on. The EOTech XPS2-300 is not night vision compatible.
The reticles can easily be seen against light targets in desert, tundra, or snow-covered environments as well as in extreme low-light conditions without washing out the target.
No muzzle side signature is visible under normal use. The reticle in the EOTech XPS2-300 is a 68 MOA circle with two one-MOA aiming dots. The reticle is calibrated for the 300 BLK but compatible with any weapon platform and usable with or without magnification.
With a conventional reflex sight, a glare elimination filter is necessary to eliminate glare as a result of reflective coating and the curvature of the lens. Besides adding cost to the sight, this filter reduces the effective light transmission by approximately 20%.
All optical surfaces on an HWS are flat. They’re treated with a scratch-resistant anti-reflective coating to eliminate additional muzzle side signature due to reflective glare. A glare elimination (“kill flash”) filter is not needed.
If you shoot the 300 BLK and like the HWS, the EOTech XPS2-300 may be just the ticket.