ORIGINAL: vabyrd
With drop in parts, you may have something that goes bang on occasion. Do this. Get a scematic and make a list of the cost of all the raw parts, and add it together. You'll be surprised. Save some misery and get a STI.
I would like to get an STI, but they are illegal here in California. Thats why I think I could get around the law my building one. But, it sounds like they are not just put together and shoot like AR's, I was hoping they were. Oh well, I find a way to get one someday.