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AR-15 Trigger Assembly fluke

rott357
Hey folks,

One of my AR-15's with a PWA/Bushmaster lower with a two-stage mechanism (safe and fire) would fire as fully auto when the trigger was backed off slowly. I thought this was just an accident, a fluke per say. After feathering my trigger release further I found that it would do this anytime, at least a three round burst, a full magazine if held down that long.

In most states in the US a fully auto rifle or pistol is a definite no-no. The lower was purchased on GB so long ago that I couldn't remember where or when I had bought it, but before giving it up to the local law enforcement agency I wanted to know how this was caused.

To make a long story short, it was simply a human error of a previous owner~~possibly accidental or maybe on purpose. Who knows?

What I found was that the hammer spring had been installed backwards, giving the spring about twice the usual tension. The hammer's return was simply a few thousands of a second faster than the seer moved to stop the cycle for a semi-auto shot. After re-installing the trigger tension spring correctly it works perfectly, just as it should.

I wouldn't recommend trying the reverse spring assembly because it's dangerous and usually illegal. Maybe this bit of information can keep some of you out of trouble. It could cost someone many times more than the value of the rifle. I'm curious if anyone else has experienced this same fluke. Happy shooting.

Best regards to all,
Rick J. (rott357)
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Comments

8 comments

Date Votes
  • givette
    Do you have a two-stage (target type) trigger? I'm a little confused about what exactly is "two stage". All civilian AR types have safe, and fire. The safety lever is not regarded as two stage. Only the trigger pull, if you have a target trigger installed. Please clarify.

    And when you refer to the spring installed backwards, I can't duplicate that in my AR. Did you mean "upside down"??

    I know I'm being picky, but I'm very concerned over this. You've brought up a full-auto firing problem by simply having a spring installed wrong?? We all may have full-autos and not know it?

    Please check your sear/hammer for excessive wear. And the receiver holes for looseness. Thanks for your cooperation. Joe
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  • rott357
    Joe, fire and safe is all any semi-auto AR-15 has. I trained with the original in the army infantry in 1968, was luck enough to get a closed flute with forward assist while in Vietnam in 69-70. Believe me, I'm not a rookie.

    A semi is a two-stage; a fully is a three-stage mechanism. Like I said, the spring was simply reversed. I didn't say upside down or anything else, just reversed. With the legs of the spring pointed downward it will only go onto the hammer two ways, correct or incorrect.

    Rick
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  • dan55362
    Seems like a loaded question!!!! If I were to answer yes, I had this happen to me, would there be a black helicopter flying above my home[?][?][?]
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  • givette
    Thanks, rott. Reversing my hammer spring now. Leaving the trigger spring and the little sear spring alone. Will do a function check and get back to you. See if I can duplicate the problem you had. Joe
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  • rott357
    Dan, check with Jack Bauer on that because it wasn't meant as a question to endanger anyone. If this is a game room then I'm in the wrong place.

    Thanks, Joe. Please let me know what you find. Remember to release the trigger very slowly when you test this experiment. Rick
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  • givette
    Reversed the hammer spring. Did the function check. My sear is catching the hammer every time, no matter how slowly I release the trigger.

    .....sorry to be such a pain, but your post really had me concerned. Joe

    EDIT: I was thinking of my nephew, more than anything else. He's eventually going to get this rifle. He really wants my AR (M-16), and the stories of me in Vietnam that I'll tell him only when he agrees to clean it for me. Best, Joe
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  • rott357
    Thanks again, Joe. Now I'm really at a loss for words. I used all new parts for everything in the mechanism, just in case. Until the hammer spring was turned around the problem still existed. My lower is older so all I can imagine is that it may have some warpage that exacerbates with more tension on the spring when reversed? After more testing tomorrow I'll advise you of what, if anything, I find. I will even reverse the spring on a new Bushmaster lower to see if the problem still exists. Rick
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  • givette
    Rick, please keep us posted. Just to be sure, before reassembly, I checked with ar15.com and the lower assembly procedure showed, when fully assembled and in place, the hammer spring legs extend rearward from beneath the hammer spring coils. Not on top. I'm sure that's the way you had it originally. Something's not right in Denmark. Joe
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