Originally Posted by bruce_ventura
They're OK but they definitely should be lapped. The weight savings is so small, I would look to other opportunities to save weight.
The manufacturing process appears to start from an extrusion. The base is machined to fit individual receiver models. The rings are are left as extruded (not machined), however. Lapping shows they are not round. Using them without lapping will deform the scope tube, which could lead to a variety of problems.
Plus, if you later discover you have a boresight misalignment between the scope tube and rifle bore axes, you can't easily fix it using these rings. Standard dovetail and Weaver bases allow you to use Burris Signature rings to correct large boresight misalignment problems, or add elevation bias.
I'm going to disagree with your first statement. Every set I've bought from Talley has been through bored and are for all practical purposes cylindrical, however, I lap everything. Keep in mind that when rings are manufactured, they are sized as a solid and then split so there will always be concentricity issues because the tube will be slightly larger than the bore when manufactured. Boresight misalignment cones from more than ring/mount placement. The machining the mount holes in the receiver, the rail and the rings can aggravate alignment. Don't lay blame on just a ring or mount set. There are a lot of variables in machining the components that come into play.
On your second statement, I wouldn't use Burris plastic insert rings to support my toilet paper roll, let alone a scope. They lack the frictional grip to overcome even moderate recoil. Might be fine for an air gun or a 10-22, but anything with recoil, I have had no luck with and I tried them on a 308 and peddled them on Flea Bay.