Well first, you need to shoot it sandbag-rested and see what the group sizes are. Don't sweat the location of where they're going, as long as it's on paper, look at the group size. You should be able to pull 2" within 15 yards without too much trouble, with decent ammo in the actual caliber for the gun. In other words, if it's a 44Mag, don't test with 44Spl.
That tells you whether or not the gun is fundamentally OK. If the gun doesn't pass that test, you've got more problems than the sights.
If it does pass: next step, see if you can dial in the sights to print to aim.
Every once in a while we see a Ruger with a loose rear sight can shifts a tad on every firing. That will screw you up good. A crude fix is to shim it with something, or better, switch to a Bowen rear. But it's more common to see inaccuracy via other issues, anything from basic misalignment/timing to a ding in the barrel's insides (usually right at the muzzle).
The "revolver checkout" process may tell you something about what's going on.
I strongly recommend not automatically blaming this on the sights, esp. not the basic sight type. The majority of Ruger adjustable sights are not prone to wiggling and work great.
