Warning: As with anything pertaining to firearms, you MUST follow all safety rules. Eye and hearing protection is mandatory. Do not point a gun at anything you do not intend to destroy and NEVER, EVER put your finger on the trigger unless you are ready to shoot. You WILL have a negligent discharge, guaranteed! Use only firearms in good working condition. In addition, consult the services of a competent, professional gunsmith for all repairs or adjustments affecting the safety and reliability of any firearm. Never perform this adjustment in a setting where injury, death or property damage could result if a discharge occurs. You are responsible for the safe operation and maintenance of your firearm, so do this and any other repairs at your own risk.
I got my Ruger SR9c back in September to replace my Beretta PX4 Storm Compact, a gun that was dead on accurate at seven yards or more, but was a pain in the butt to carry and sliced my fingers trying to shoot on more than one occasion. The Ruger was lighter, thinner and striker fired, which should have made it a joy to carry and use, but the accuracy was just not there. Sure, I could hit with it, but not accurately or consistently enough to keep all my rounds on paper at the prescribed distance. Even in a high stress situation, you still need to be able accurately hit your target. On most handguns, the sights are fixed and require some gunsmithing to get to rights. On the Ruger SR9c, the front sight is adjustable with a drift, but the rear sight is adjustable with an Allen wrench and a slot screwdriver. For the most part, this gun should shoot accurately right out of the box. However, mine was shooting low after many attempts to correct my stance, etc. I couldn't even blame it on recoil, or "anticipating the kick" as the recoil on this piece is nearly non-existent.
There are two adjustments on the rear sight. One is for elevation, and the other for windage. Elevation is adjusted with that slot screw and the windage is with the Allen wrench. For the most part, you will never need to adjust for windage, or left and right on this gun. Elevation, because of the trajectory or path of the bullet as well as holding and aiming the gun and your depth perception will affect how these sights need to be aligned. At twenty one feet, the bullet isn't going to drop that much and this is where you need to be able to hit accurately. For this, I was back about twenty eight feet, or a little over nine yards. To sight this gun without a bore sight, you will need to load a few rounds of the weight you intend to carry (I use 115 grain), align the front sight with the target. This like putting a pumpkin on a post, so to speak with the target on top and "touching" the front sight. Align the rear sight so the front sight is centered in the notch of the rear one and level with each other. Fire off several rounds and note where they landed. If they ended up low, tighten the screw, lowering the rear sight a little. If they land high, loosen the screw. Fire off a couple more rounds and adjust until the said rounds hit where the sight picture is. This takes some practice, and a little trial and error, but you will get the rounds where they need to go. As long as you consistently hold the gun properly and align the sights, it shouldn't take more than one or two adjustments to get this right. Regardless, you're not striving for pinpoint accuracy, but to place your rounds in a tight group of about four to six inches, maybe less. The trick is that the sights need to go where the rounds are landing and vice versa. Then you can take full advantage of the accuracy of your gun. Hopefully, this was helpful as I'm not a gun expert, but a gun realist.
Update: I got the Ruger as accurate as it's going to get and have about 500 rounds through same without a malfunction. I fired 120 today without a problem. Maranatha!