I have a M&P15T purchased around 2013. It's the one with the UTG rail. During a move it was put in storage along with some spare parts from other rifles. After 3 years I got it out to find that it was without the bolt carrier group. It must have been mixed in with the spare parts and other BCG in several other boxes. If I remember correctly it came with an AR-15 carrier instead of the heavy M16 carrier, but I don't remember if the bolt had any markings or not. I found one that might be it, but it has no markings, no MPI or HPT on it. It has a plain steel extractor spring with black o-ring. Does anyone know if the bolts are marked in any way?