First off, I wasn't sure which forum I should post this in, so I'd like to apoligize before I get 500 people yelling at me.

I am making my own movement function from scratch, and what it does is i make a couple vector that keeps track of about unit below the players feet. I trace from one vector to another, and if the trace makes it all the way across (then there is obviously no object there to block it) then i move the player down a little bit. So this way, the player falls down if nothing is below him.

Now here's the problem:
When I use a .mdl for my ground, it doesn't always register right. Like I can make just a normal block and walk around on it and he'll fall down when he's still got a ways to go before the edge. It's like the engine does'nt accurately read where the block begins and ends or something.

Yeah a5 doesnt have the greatest collision detection on .mdl models for surfaces. It would be best to use blocks or map entities

but then i couldn't really make a block that moves back and forth like on a simple platform game or something since i can't make the blocks move.

yes you can. YOu have to make a map entity, meaning you build your moving block as one level, then build the map. Then in your main map, go to load map entity and load the file and then you can add the action to it

That was just one of the reasons i want to use models, but i guess since you got me there...i just want to use .mdl's okay , lol. But ya, cause they are easier to customize and skin so they look better instead of texturing. I'm not going for a huge level here, so a model and a skin would cover it.

mkae sure your models are aligned at the origin correctly in med, so they wont fall through things. The collision is based off of the first frame of animation.