I have assemebled most of my uppers with parts of my own choosing. All are flat tops, none wear iron sights, and those that were intended to shoot cast bullets have forward assist. I despise quad rails for both their size and abrasive nature. My preference is for handguards just long enough to cover the gas block, or even to leave an adjustable gas block exposed. I favor variable optics, genrally LPVOs, but have used dots, prisms, and even up to 12x variables.
Most of my uppers have thread protectors, and those that don't wear a simple linear comp that directs blast downrange. I don't have any flashlights to provide an aiming point for somehone else or lasers to slow my presentation while searching for the dot. There is nothing quicker than a shotgun for up close work.
My lowers have better than milspec triggers, and other than the typical plastic, finger grooved grip. Buttstocks are of both the fixed and adjustable variety depending upon the intended purpose.
I do shoot cast in 300BLK and 5.56. My 300BLK proved itself some years back when I shot in a cast bullet match out to 500m. I tied for high overall that day with 4x while shooting against a Tom Gray built Rem722 in heavy barreled 35Rem with Jewel trigger and 25x Leupold. My 9 twist 556 loads seem to shoot as well at 200 yards as they do at 100, and I do shoot them to 300 on my local range if the wind and mirage aren't too hateful. If they aren't "full function loads", I don't shoot them in gas guns.
While they don't have the soul of blued steel and walnut, these adult tinker toys can be useful tools.
