Rail Handguard
Choosing An Eotech Sight
At first glance the sheer scope of the range of holographic sights can be intimidating. Each model, however has a unique combination of a small number of features. The Eotech holographic weapon sights have the following features:
Night vision compatability. To keep the price down, Eotechs intended for action shooting, hunting and most law enforcement applications are supplied without the night vision settings. The XPS2, 512, 516 and 517 lack night vision.
Price. The cheapest Eotechs are those lacking NV settings – the XPS2, 512, 516 and 517 again.
Close mounting of night vision or magnifiers. If you want to mount NV or a magnifier right up to the rear of the unit, pick a model with its NV and brightness buttons on the left hand side. The EXPS, 556 and 557 have side mounted buttons and are NV buttons. The 516 and 557 have side mounted buttons but are not NV compatible.
Height of the sighting plane. Some Eotechs come with a 7mm riser to facilitate co-witnessing of iron sights in the lower third of the sighting window and to allow compatibility with a wider range of night vision units.These are the 516, 517, 553, 555, 556 and 557. The QD mount supplied with the EXPS is 7mm higher than the integral unit of the XPS series.
Mounts. The holographic weapon sights come with one of three mounting systems – allen bolt, thumb screw or QD quick release lever. The XPS, 516, 517, 556 and 557 use the thumb screw, the EXPS, 553 and 555 have quick release levers and everything else uses alan bolts.
D-ring clearance. Eotech offer models with cantilevered battery housings to clear the Delta rings of AR15 derived rifles. The XPS, EXPS, 516, 517, 556 and 557 are designed with this feature.
Length. Holographic Weapon Sights come in various lengths dictated by their battery and mounting arrangements. This can be critical if you are using the sight with in-line night vision. Twin AA battery models are the longest, followed by the twin CR123 units, then the amazingly short, single transverse CR123 battery XPS and EXPS series. The XPS and EXPS are 3.5″ long, the 553 4.9″, the 556 5.0″, the 512, 516 and 552 5.4″and the 517, 555 and 557 5.6″.
Ballistic reticle. Only three Eotechs have ballistically matched dots – the 557.AR223 is matched to the 5.56mm NATO round, the 552.XR308 to the 7.62 NATO and the 552.XR500 to the .50 BMG. The 557.AR223 has side mounted brightness and NV buttons whilst on the 552.XR.308 they are positioned at the rear. The XPS2-2, XPS3-2 and EXPS3-2 offer a 2 dot reticle but this is not matched to a specific cartridge.
Batteries. In an endeavour to boost battery life and availability Eotech switched from ‘N’s to the AA and CR123. You need to choose between the AA and CR123 with some models only differing in which they use (for example the 553 and 555). The AA has significantly longer battery life when used with lithiums (1000hrs vs 600) but CR123 models are more compact. A single CR123 (transverse) is used in the XPS and EXPS series, two CR123s in the 516, 553 and 556 and two AAs in the 517, 552, 555 and 557.
Military heritage. The US DoD has formally adopted the 553 for SOCOM, whilst individual military units like the 1st Stryker Brigade, 3rd Infantry and 10th Mountain brigades have adopted 552 versions. The 555 is a 553 adapted to AA batteries and otherwise shares its heritage and specification.
Color. The 512 series is available in black, Mossy Oak and Advantage Timber camoflage. The 553.A65 is available in black or tan.
Integrated laser. Only the EOLAD series have integrated lasers.
Copyright Chris Pieterman 2010.
AR15/M4 2pcs QUAD RAIL FORARM HAND GUARD INSTALLATION INSTRUCTION