I was going to shoot my WOA SPR upper, but I accidentally hit the FSB and knocked it off center.

How is the heck does one get those straight, back to mechanical zero!!!!????

You can bet that I am using red Lok-Tite or Devcon Steel Putty to hold it.

i just eyeball it.


there should be a dimple on the bottom of the barrel that you could align with the hole in the fsb.

So that is what that dimple is for.  Align the bottom set screw, then snug the others?

And somewhere along there, use something to hold it in place.

Do you have the flats on your barrel for the setscrews?

Yes, two flats (one on each side) with a dimple on the bottom.

Quoted: Yes, two flats (one on each side) with a dimple on the bottom.

It shouldn't have moved with that much setscrewage.

Agreed, provided they had some torque, which was lacking (my fault).

I used dual bubble levels and a receiver block.  Turned rifle upside down in vice.  Placed level on milled underside of upper receiver (which is now facing up).  Placed other level on flat part of FSB where the sling swivel would have been (milled away, flat).  Moved FSB so both bubbles matched.  Set dimple screw.  Checked for level again.  Installed side screws and torqued at same time.  Checked level again.  Went outside to bore sight and compare to mechanical zero.  It came out fairly close....MUCH better than it was at the range.

Range session will prove if work was good or bad.

I made a bunch of assumptions: receiver underside perpendicular to rear sight; FSB milled flat perpendicular to front post; my choochoo has not gone chuggin around the bend.  I checked the levels against each other: they read the same on each surface in the same place, and side to side.

Hope I did it right.  Seemed like the best way to do it.