Let's talk about rests for moment. Rests are a very important part of the process of playing metal rhythms. A rest gives the music a chance to breathe and it's not just a matter of stopping the chord. It's actually a matter of dampening the chord in time with the music. You'll hear this done with a lot of great riffs, stuff like Smoke on the Water by Deep Purple has great rests, so does Master of Puppets by Metallica, Symphony of Destruction by Megadeth, War Pigs by Black Sabbath.
So when you do rests like this, it comes from this part of your hand. You always want to play in time. Oh, I should mention ACDC too, another great band that does rests. Listen to Back in Black and Dirty Deeds Done Dirt Cheap. I'm going to play a chord, and I'm going to stop it. See how that's happening? It's right here, this part of the hand. I might be able to do this with eighth notes if I'm playing to a tempo like this. Three, four. If it's a slower tempo I can subdivide into 16th notes. If the tempo is this, but I'm hearing da da da da da da da da da da da da da da da da, so I can take the chord and then hit the rest in time.
Notice I'm using the volume knob to turn off the rhythm especially with metal guitar tone because it can be very loud and noisy. There I'm shutting it off with just the volume knob. Here I'm just going to use my palm. There you have a few examples of fun things you can do with rests.