The eyepiece tube threads into the erector assembly with right hand thread. Step 2 – Remove the rear eyepiece tube from the optic. Use a tooth brush and thoroughly clean the exterior except the lenses, then use glass cleaner and thoroughly clean and blow off the body with compressed air. It is important the optic is clean and free of dust, oils and debris that could potentially get inside the optic when doing the conversion. Step 1 – Thoroughly clean the exterior of the optic USMC MST-100 & MST-100M Glass etched reticle retrofit instruction Reticle cell available for $149.99 shipped to CONUS and CanadaĪdditional items needed to complete this work, click the pic and it will take you to the link. The key to the installation is to ensure the reticle is true to the old reticle grooves and it is concentric to the centerline, that and ensure you don’t get dust inside the optic.įor about 5% the value of your optic you can have the cell needed to repair your piece of history. Any optic repair outfit will be easily capable of installing the reticle cell on the back of the reticle cell holder with a very fine ring of epoxy such as the epoxy shown in the picture that can be purchased at most big box stores or Amazon. The replacement of a blown reticle is well within the capabilities of the untrained, as long as they are very finicky. With that said, if you are doing this retrofit do it in the cleanest area with warm dry air you have available to you.

Anybody who has used these optics in less than acceptable climate conditions know they can and do fog, this is why. And change in temperature or adjustment of the eyepiece both create an atmospheric pressure change inside the optic creating either pressure or a slight vacuum. The eyepiece focus adjustment is not and cannot be sealed effectively thus making the optic unsealed. The MST-100 optics by design, are not Nitrogen purged and sealed. If there was enough interest we could produce etched football reticles as well as the true mildot. The dots are a cleaner round shape rather than the inconsistent football-ish shapes made by dripping resin onto the wire.

The glass etched reticle takes this to the modern era with no discernable optical difference with the exception of perfection in spacing of the bars and dots to a true mildot. It is amazing what John Unertl was able to accomplish when he designed and built these scopes creating the first Mildot scope, with the resin dots on the tungsten wire, perfectly spaced to create the Mildot reticle, amazing craftsmanship that is extremely difficult to replicate. All of these old scopes are just waiting for the tungsten reticle wire to fail rendering the scope useless. If you own a USMC MST-100 from an M40a1 or the Canadian C3A1 MST-100M scope you will understand why the glass etched reticle is a great idea. Available only through Sentinel Tactical is a glass etched reticle retrofit for the USMC UNERTL MST-100 & MST-100M.

Usmc unertl scope repair