This K31-OBM is intended as an accessory to be used in conjunction with the existing K31 clamp on scope mount.
Slide the OBM over the K31 clamp on scope mount dovetail rail, and move forward until it stops. Using Blue Loctite, insert the three rail screws and tighten but do not over tighten! The Blue Loctite will keep them in place.
The next step is to slide the deflector into the provided space between the bottom of the OBM and the top of the K31 mount. There is a relief slot machined into the bottom of the unit provided for that purpose.
Now apply a light grease to the edge of the deflector and insert the 3 small deflector screws down against the crimped edge of the deflector and secure into place. Do not over tighten!
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Contrary to what you may have heard, the K31 rifles do not eject spent cases the same, one rifle to another. Your deflector is positioned and bent at the point of manufacture to work across a number of K31 rifles with 100% ejection. Yours may not, but you can find that "sweet spot" for ejection by using both hands to gently bend the deflector either up, or down. If that does not allow for clean ejection, gently bend the deflector to th original position an bend just the front or the rear side of the deflector, test for clean ejection. You may have to bend just the rear edge of the deflector to accomplish clean ejection. By experimenting, you will find the correct position for 100% clean ejection. Bear in mind it takes very little bending to control the angle of the ejected case.