A fixed diameter insert system to offer an alternative to the adjustable iris's currently available in the following existing 1 1/4-28 UN threaded 30mm front sights.

• RnR Design (Riles) 30 mm front sight
• Ross 30 mm "Beer Can" front sight
• Stallings 30 mm Rightsight front sight

The Fixed Insert Aperture System consists of a 2 inch long retainer and an assortment of fixed clear plastic aperture discs. Each insert is literally hand made to the specifications of the customer for his/her particular use. The inserts fit into the precision retainers with a calculated amount of holding pressure for each installation retention.

The principle is to allow one retainer to be installed in the sight tunnel with any sized insert and the remaining retainer be used for another pre-selected insert to be assembled and set aside for later use. Each assembly can be handled and removed/installed into the sight tunnel without having the selected insert fall out of the retainer. The manufacturing tolerance of the retainers and inserts is held very close, therefore care must be taken in storning and handling of the apertures and retainers to insure a continued functionality.

Insert apertures are fabricated with the metric system for size, this seems to be the standard for the adjustable iris's and the easiest for reference reasons. Each insert is marked with the aperture size via an engraved designation on the surface opposite the chamfer. The selection of aperture size is in 0.1 mm steps, roughly 0.0039 as a minimum. The discs are manufactured to a very close concentricity and diameter tollerence and do not require indexing to prevent a zero shift with aperture changes.