So some songs when they are strumming the strings that are muted and it gives that nice metallic rock sound. When i try to get this sound i just leave my fingers on the strings i need to play but don't put pressure on them and play them. It sounds alright, but its more of just a dull muted sound, and not a metallic rock n roll sound. The rest of the song sounds right but when they do some muted parts inbetween power chords it doesn't sound as good. Any way I can make it better, am i doing somthing wrong? Sometimes the dull sound works better for songs sometimes i need the more harsh metallic sound. Anyway i can get it more like that?
Are you using distortion? Distortion when palm muting makes a huge difference versus how it would sound without any distortion. I'm not just talking about a little bit of gain, I mean overdriven and DISTORTED.

Also, while you don't necessarily need to use a pick to get a good palm muted sound, its easier on your fingers and you will get a more defined sound. Don't know why it works with a pick and distortion ( finger picking on acoustic is more defined than with a pick ironically) but to my ears it sounds better. Make sure you get a pick, and practice your downstrokes (alternate picking is also perfectly fine and easier on your wrists).

Lastly, make sure your putting the back part of your wrist is resting right at the place where your strings and the bridge of the guitar meet (where the strings go into the body). If you put your wrist too far up the string away from the bridge, you will hardly get any sound out. If this is the problem, just slowly try practicing a scale run or a lick with your palm in the correct positioning. a few hours doing that you'll be money.

Best of luck!
You can try to hold the pick kinda crooked from the string, it makes it sound realy "harsh" and "metalic" instead of "dull" when holding it perpendicular
Checklist -

1. Are you using the bridge pickup?
2. Is it a humbucker?
3. Are you using enough gain?

if you meet those criteria, then it's probably an issue with your technique