For what it's worth, I've been wondering for quite some time how to use the grenade sight on my Yugo SKS 59/66, and how to lower it once deployed in its up position. Here's what I've found: 1) How To Lower The SKS Grenade Sight: When deployed, two spring-loaded pins pop into place in the base of the sight to hold it up. If you take the heel of your hand and gently pound against the sight to try and push it back down against the barrel in its stowed position, you'll notice that the pins try to retract a bit. In other words, keep gently but firmly pounding the sight towards its downward position until the spring-loaded pins have retracted enough to free the sight to move the rest of the way down until in the stowed position. IMPORTANT NOTE: before pushing the sight back down, make sure the gas operation selector button is in the 12 o'clock position so you don't bend or break it when pushing the sight back down to the stowed position. Once the sight is down against the barrel, THEN return your gas operation selector button to the 2 o'clock position. (if you forget, you'll be given a reminder when you realize that your SKS doesn't chamber new rounds after firing) 2) How the heck do you use the SKS grenade sight?: It seems to be marked backwards, doesn't it? One would expect the distance markings to DESCEND in distance as you go up the sight, but the opposite is true. This only makes sense if the grenade sight is used as a REAR sight, which it is! Thinking of the grenade sight as a rear sight, the shooter lines up the notches along the "ladder steps" of the sight with the ogive of the grenade (which acts as the front sight).