I guess I misunderstood your question. I’ll try again. If I get it wrong again, please elucidate better what exactly you were asking.
The implication for Orlando of the police being incredibly bad shots is that some of the victims may have been shot by police attempting to stop the perp, either during the initial shootout, or when S.W.A.T. entered three hours later. I have seen no actual evidence for or against this theory.
The .223 cartridge used in the standard AR-15 style rifle, including, I believe, the Sig Sauer MCX used in Orlando, is known for often going right through a person, leaving them alive, but likely to bleed out without proper trauma care. By taking three hours to enter the club, that S.W.A.T. team may have allowed some of the victims who could have been saved to die of blood loss.
The Sig Sauer MCX is also available in .300 Blackout and 7.62x39, both much more effective rounds against thin-skinned targets (like deer, or humans).