Found a screamin deal on a S&W M&P 15 stripped lower and got it for my son for his 15th birthday. He is buying the DMPS lower parts kit and I will teach him how to polish the trigger parts, tweak springs, etc. After all that fun stuff, I wanna find some inexpensive used parts so he can get the gun up and running. He can allways replace and resell parts as he upgrades, but for now I want him to get it built as inexpensively as possible. I bought the lower, the rest is up to him to pay for. So does anyone have any used AR parts laying around for sale?