I always get uptight about tightening bleeders on a caliper. Is there a spec of
                  this or just stop when no more fluid runs out under pressure?

                  As a rule of thumb, I tighten them about 45 degrees past when I feel the base of
                  the plug contact the seat. Still, they will occasionally snap off due to the
                  inherent weakness at the neck. But, at least it leaves you a nice round hole, into
                  which you could slip an "Easy-Out" and maybe lose 5 minutes off your day.

                  So, stop freaking out and fix your brakes.

                  --
                  If you choose not to decide, you still have made a choice

                  As a rule of thumb, I tighten them about 45 degrees past when I feel the base of
                  the plug contact the seat. Still, they will occasionally snap off due to the
                  inherent weakness at the neck. But, at least it leaves you a nice round hole, into
                  which you could slip an "Easy-Out" and maybe lose 5 minutes off your day.

                  So, stop freaking out and fix your brakes.

                  --
                  If you choose not to decide, you still have made a choice

                  This is exactly what I want to avoid, snapping it off. Certainly there's a torque
                  spec for these somewhere?

                  Ok, suit yourself. 5.5 - 8.0 ft/lbs. But you'll need a crows foot and 2" extension,
                  connected to a torque wrench that has been calibrated and offset to precisely
                  counter act the abrogated readings caused by indirect coupling to the torque
                  measuring scale.

                  Good Luck.

                  Better yet, just use your brain and snug them up. In 20 years of doing brake
                  jobs, I've snapped exactly 2 bleeders. ALWAYS on a car more than 20 years
                  old. And both were on a backwards mounted wheel cylinder for drum brakes.
 

                  --
                  People think I'm insane because I am frowning all the time. -Ozzy Osbourne,
                  1973