Since I own several ARs and the op said he had to turn his post all the way down the free floating hand guard of the MPR would be off center up.It could be something as simple as adjusting the sights. The front sight is adjustable for elevation and the rear sight is adjusted for windage.
Ooooo, you own several. Who doesn't? I'm a builder, personally. Off center should be obvious and might appear in two areas. One area to check would be the fit between the handguard and the upper receiver, while the other would be concentricity of the barrel within the handguard. The two issues that come to mind would be a loose handguard and/or a loose barrel. With the gun unloaded and cleared, with the upper receiver removed, check to see if the barrel appears to be centered in the handguard. Look to see if the handguard appears to fit tight against the upper, also if the upper and handguard rails are aligned and tight. Honestly, most handguards almost align themselves. Then check the bolts on the handguard to see if they are tight. If both are tight, grasp the handguard and check the barrel for movement. Very slight flex is normal, but there shouldn't be much. Tightening a loose handguard amounts to not much more than routine maintenance. A loose barrel needs to be done right by someone who knows what they're doing. While have the tools and experience to do it myself, I'd let Ruger do the honors. There's no good reason for a barrel to be loose and I'd let them determine why it happened.Since I own several ARs and the op said he had to turn his post all the way down the free floating hand guard of the MPR would be off center up.
I've owned a mill and lathe for many years, actually. Now, just take off the handguard. Inspect for damage and reinstall. The handguard is more or less self-aligning unless it's damaged. An over torqued barrel will also throw things off.Oooo? Really? Ooooo? So you're builder? I suppose you have a mill and lathe? Or do you pin parts together and torque a barrel nut? My freakin hand guard was over torqued and is pointing uphill compared to the freakin barrel. Is that freakin good enough for you or should I tell you how many clicks down I put the post to hit the freakin bulls-eye Mr Builder?