A week after my A-2 Ka-Boomed, I'm still researching the possible causes, and I think I found something. I had downloaded the PDF file with the Oly Owner's Manual, but hadn't looked at it for quite awhile. Silly me, I thought all AR parts were pretty much interchangeable between makes, but apparently that's not so! On the FIRST page of the manual, Oly tells me NOT to swap bolts or carriers between guns. "To do so may cause damage or injury to you or your rifle." Well, guess what, that's exactly what I did.
My Oly is a Match-Target heavy barrel model, stainless barrel close to an inch in diameter, but I could never get it to shoot up to my expectations. I also got tired of the weight, and decided to get a different upper, something lighter and handier. After shopping around, I bought the A-2 upper from Del-Ton ten months ago, and have been delighted with its performance. The chamber was cut to .223 specs, whereas the Oly was a 5.56. I quickly found that ammo that would feed flawlessly in the Oly wouldn't even chamber in the Del-Ton half the time, until I began sizing it down to minimum specs. But in discovering that, I found that if an oversize round was fed, it would not let the bolt close, yet it still went CLICK when I pulled the trigger. Were the gun unable to fire out of battery, it shouldn't have done that, but I never made the connection. It only cost me about $500 to learn what that CLICK meant.
I was trying to save $85 by not buying Del-Ton's bolt and carrier, figuring that all AR parts are made to the same specs and were totally interchangeable. Well fuck me running backwards, I guess they ain't. Experience can be expensive. I just hope somebody else reads this before they make the same mistake. I spend a lot of time lurking on forums like this one, and I've learned a lot. I'm close to fifty, but I'm still alive and have all my fingers and eyeballs, simple proof that the Lord loves fools and drunks. Sometimes I've qualified on both counts. They say what doesn't kill us makes us stronger. I'm not sure about the stronger bit, but I'm just a hair smarter than I was last week.
My remaining question is why it took close to 2,000 rounds for this situation to rise up and bite me. Guess I was just lucky, eh?
Papajohn the Enlightened