Re: AR advice
The M&P's are a good bargain.
Goodoldboy- If you can find an off the shelf rifle that is set up the way you want it and don't customize, I don't think you'll save a whole lot by building your own.
But, if you think your going to want to change out parts (handguard, sights, charging handle, etc) then, I think a build will be more economical. Just about all that's left of my Bushmaster that's factory is the receivers, barrel, and trigger (and that's going to go too). It would have been a lot cheaper for me to have build it myself at this point.
The Second Ammendment...
Its kind of a big deal.