Does anyone know if Century lowers are forged
or cast?
Also what is the quality of Century Lowers?

The Century Arms lower I saw at my local gun store was forged. I don't know the quality, it appeared to be well manufactured, but I didn't like the "raw" gray parkerizing, and an Eagle Arms lower they had on hand was $10 cheaper, and had a much better finish.

I've got two.  Very nice, good quality.  They are forged and the colors match my DPMS uppers.

I like mine.

I've built kits using both the CAI and RRA lowers. They are in every way identical. They are both manufactured by Continental Machine and Tool. Both RRA and CAI lowers Have serial numbers that read CMXXXX. The CAI lowers are nice, but if you use one, your finished product will say Century on it, which is a knock in many circles. If you never plan on selling, they are just fine. If for some reason you should have to sell the rifle plan on getting $50-$75 less than you would for a rifle built on a Rock River or some other quasi-namebrand lower and a whole lot less than if it was built on a top namebrand lower.

I have two CAI lowers built on one already. Looks great with my RRA upper. They are well built forged lowers. I bought from a guy on AssaultWeb who comes up with these lowers every once in a while. I have three other friends that have these lowers and all like them. If you can handle the off brand name they are good lowers.

I also have two cal lowers the quality and color match is great.
                     Bill