Thread: Steel bar to check scope ring alignment?

Yep, a couple of short pieces of 1" cold drawn or ground bar, face the ends square on the lathe and you're good to go. Mine are pointed on one end and flat on the other; the flat is more useful. I find that as long as the flat ends can be brought close to one another when mounted, there is no need for micrometers etc - alignment by eye can be very accurate with a bit of care.

They'll do things that a lapping bar won't, like allow you to easily check when turn-in type rings are aligned with one another.

While you're at it, a lapping bar can be just a bit longer piece of similar steel with a handle attached. Mine is a piece of 25mm round steel - I use spray adhesive glue to attach 400-600grit wet and dry sandpaper to the rod. That brings it up to 25.4mm (1") diameter and it's quicker and cleaner than lapping grit. Using sandpaper also means the hardness of the rod (or the rings you're lapping) is not critical, just check the bar is round and straight.