In my professional opinion, get rid of the rifle and start with a new one.
The lives of your Officers and the people that you serve each day, may depend upon that rifle working 100% in all field conditions. If you rebuild it, it may work just fine and all is good to go. If you rebuild it and it fails, are you willing to assume the liability of a catastrophic failure where things blow up and someone gets injured, or worse where it fails to work in the field and an Officer or the public that we protect gets hurt or killed are you willing to be responsible? For the cost of a rifle, replace it.
In the Armorer courses that we teach, we cover the problems of mistaking a 300 Blackout in a .223/5.56 barrel, and show numerous examples of it.
In the Advanced Armorer courses that we teach, we show several examples of guns that have been blown up, had been involved in car accidents where things like a laptop computer struck it or the locking mount system had broken off sending the rifle flying, and a few rifles that had been dropped from high rise buildings, all were suspect of possible damage, but the agencies weren't sure if they were okay to use or rebuild or ditch them. In the Advanced Armorer course we show a few examples where the receivers and parts visually look to be okay. Then we gauge several of those same parts that visually look to be okay, and the gauging shows where things are bent, bowed, or sometimes stressed. We also show a few of the receivers, barrels, gas blocks/front sight bases, bolts, and bolt carriers that visually look okay, where we either have done a magentic particle inspection or dye test, which then shows where there are cracks and stress showing things that aren't normally observed by the human eye.
CY6
Greg Sullivan "Sully"
SLR15 Rifles TheDefensiveEdge.com(763) 712-0123