B. Adams wrote:
I bought some metal receptacle boxes at Lowes. They do not have
grounding screws. When I install the receptacles, I will of course
attach the ground to the ground screw on the outlet. Will the contact
between the yoke and the box be sufficient to ground the box?


No, because when you remove the outlet the box will no longer be
grounded. If you ground the box (you'll have to add a screw or a
special UL-listed clip) you might not have to ground the outlet if the
outlet has a little copper spring on one of the screws and is listed as
"self grounding".

I usually wrap the ground wire about 270° around the screw in the box
and then continue on to the outlet. I learned that trick here. :-) It
works better than using a wirenut.

Those ground clips are hard to use IMHO and not worth it.

You can always use plastic boxes and then you don't have to ground them.

Bob