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Re the Elcan 1-4 this was Elacns input into the ECOS (Enhanced Combat Optical Sight) for USSOCOM (parts of MD/NS - M4 Sopmod Blocks II and III)
It has some eye relief issues - in that the 1x and 4x setting are quite different. It still has external ajustment - specifically the same Elcan mount - so the windage pin and elevation dial screw take all the weight, impact, shock that comes from the weapon or exterted on the sight. It also allows foreign material in to the adjustment mechanism - which shortens the effective life by acting like sandpaper.