OK I have a MK18 Mod0 clone I am in the process of building.  Because I live in the great state of CT I am forced to own a "Preban" if I want original equipment.

So the lower I have has a bit of wear on it and since it is a SBR I would like it to have a nice hard coat to protect it as well as for aestetics for the build.

Are there any down sides to cerakoting a preban lower? If it is bead blasted will that weaken the metal in any way?

You don't want to remove the anodizing if and when you blast it.  You can lightly scuff it with aluminum oxide without removing it and that will provide a good surface for the Cerakote to adhere to.

I like the CeraKote although it's a bit trickier to work with than some of the other offerings on the market.  Definitely the flatest finish I've seen and very durable.

I got my MKII pistol done with Graphite Black Cerakote and its great. All the markings are easy to read. As far as thickness, I don't know, about a 1 mil thick...?  

Quoted: You don't want to remove the anodizing if and when you blast it.  You can lightly scuff it with aluminum oxide without removing it and that will provide a good surface for the Cerakote to adhere to. I like the CeraKote although it's a bit trickier to work with than some of the other offerings on the market.  Definitely the flatest finish I've seen and very durable.

+1 you can blast with the ceramic ball stuff and go very lightly as to not remove the hard anodizing, but practice on something worthless first.

What if you don't blast it, what will happen?

What if you just degrease, heat, spray, and cure?

Bump, anyone ???

That's going to depend on the surface.  Anodizing can be anywhere from rather rough to pretty smooth.  I have coated over rough anodizing with nothing but a good degrease and it worked very well.  As long as it's not smooth as glass it should adhere just fine provided you get it properly degreased.

I have done 2 so far, no blasting.
the chipped places there are (just a couple) can't be helped.they took real good hits.
but the stuff sticks well, cerakote is epoxy. the bake version is 24 to 1 paint/hardener.

and it is reccomended in 1 mil thickness.I used a sample size jar for 1 AR, thats the smallest one sold.

my opinion is don't bead blast or scuff, just be VERY sure it is CLEAN and DEGREASED.
I had a place on the receiver extension that had a bit of oil film on it and left it to see what it would do.it was in a place that was not visible.you can see it.