My son recently purchased a ruger 556 in 350 legend for his 18th birthday. He's loving the rifle until today. Winchester ammo was shooting fine then tried hornady and had some light strikes and failure to fire. At first, I thought it might be an ammo issue or harder primers combined with maybe a light hammer spring on the Ruger 2 stage trigger. I decided to take the bcg apart and see if anything looked wrong. I am a certified ar armorer so I do know what to look for. What I found was the firing pin was dragging against the extractor pin. A firing pin from one of my rifles wouldn't even fit into the bolt. I mic'd the extractor pin and it was .002" bigger than one from my bolt and it looks like the extractor pin holes are too close to the center of the bolt. I swapped the extractor pin and the Ruger firing pin is now moving freely and the Ruger extractor pin works fine in my bolt with my firing pin but my firing pin still won't fit in the Ruger bolt. We'll be shooting it tomorrow to see if it's fixed. I contacted ruger and we'll see what they say. I'm not complaining just posting in case someone else is having a similar issue. It looks like a text book example of stacking tolerances which is bound to happen in a mass produced product.