[guntutor]

Often overlooked in the AR-15 bolt group is the firing pin retaining pin. If the pin is bent along its length, it may not properly seat itself. If so, the head of the pin may be making contact with the left interior wall of the upper receiver, creating a friction point. Over the years I have found many firing pin retaining pins that were worn, bent out of tolerance, or not even close to the original dimensional specifications. Many "homebrew" gunsmiths, and unfortunately some of the less gifted parts vendors, think a common cotter pin can be substituted; which is wrong. The head of this pin must be of a curved "D" pattern configuration, and the degree of curve in both directions from the apex must be identical. If not, you'll induce drag. A small detail, but in many years in practice, I have found this to be the problem more often than you would believe.
Similarly, I have observed that many people use this pin, and the firing pin itself, as disassembly tools. What a mistake! I have also dressed down hundreds of soldiers over the years for using the tip of the firing pin as a cleaning tool to remove fouling from the inside of the bolt. When a person buys a new or custom AR-15 type rifle, this is seldom a problem, but it's common to find malformed parts such as these in military service rifles or used rifles purchased at gun shows. If you acquire parts from any source other than a manufacturer, always check the dimensions of the parts.

Chuck Ruggiero
aka - Guntutor