DECIDING WHICH AR-15 TO BUILDBefore you buy your first part, decide what kind of rifle you want. Will you be varmint hunting, plinking or competition shooting? Once you make this decision, you know what type of upper receiver and barrel you will use. The upper receiver and barrel you choose will determine the remaining parts needed.Here are several types of stripped upper receivers, each with different features for different applications.AR-15 A1Has a fixed carry handle, shell deflector and requ …