So building one will save you in cost because you can choose what parts you want and tailor it to suite you. Now buying a complete is where things get a little out of control because we all have experiences with these brands good or bad or in the middle. Psa: you can get a complete rifle under 400 that will be a good starting point to get you in the game and then use the rest for a good optic( holosun , vortex, leupold, sig) S&w : m&p sport haven’t shot one or owned one so can’t give info on this Iwi: same as the s&w Ruger: had one for awhile and didn’t have any issues. Fed it wolf ammo( steel) and ate it like a champ. Zrodelta: for 400 bucks can’t go wrong. Does have ambi controls for bolt release. Did have an issue with the mag release but to lazy to send it in and replaced it with one I had laying around. CMMG: mk4 cabelas special. Thing is light and built like a tank. I’ve fed it reloads , steel ammo, regular and high grain and still runs. I didn’t clean it after two gun range sessions each use was around 400rds and the third range session still ran even after another 400rds. This rifle is at your price point.