I need to glue a metal corner bead to a plaster corner. Normally, I would nail the bead but it's masonry so nails won't go in. Should I use Liquid Nails or more like something like contact cement?
If the construction adhesive is one of the type specified for metal usage then it should work just fine. Working just fine is also assuming that the plaster is solid and not a crumbly surface.
One issue with construction adhesive is that you would need to devise a way to hold the metal beading in place till the adhesive sets up. On the other hand contact cement, provided you find one that can work on the metal part, (I have used a 3M product that sprayed on to a stainless steel backer sheet behind a stove) is applied to both parts and set to dry for a short while. Then the metal piece could simply be pressed into place without need for clamping. With the contact cement you need to be sure to get your piece lined up right and press gradually into place from one end. Usually once it is stuck on it is there to stay so you do not get 2nd and 3rd chances to line things up.