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Posted: 1/13/2014 8:13:52 PM EDT
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So here is my problem. I built an AR from parts everything looked good went to fest fire it and it just clicks. Pulled the mag, pulled back the charging handle and there was a small dimple on the primer, which I think might just be from the the firing pin hitting it when pulling the charging handle.
So I know what the popular answer will be. Check your hammer spring. Yes, I have, I can assure you that is is right. So with that said I have narrowed it down to either the trigger or the hammer. I am thinking that my hammer spring might be a little too weak. It is a Palmetto State Armory LPK. I narrowed to to the lower because I put another lower onto my upper and it fired just fine. So with all of that said I am brought here hoping that maybe one of you guys can help me figure it out. I stopped by a local gun store looking for a stiffer hammer spring they would get back to me if they had one. But do you guys think that would solve my problem? Any feedback would be greatly appreciated! |
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Odds are one or more of your FCG holes are off. Pic of the hammer fully forward, please?
I suspect the FCG wall in front of the hammer wasn't cut far forward enough, or the fcg holes are slightly mislocated, preventing the hammer from making a full strike on the firing pin. |
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The hammer spring does not look right. The coils look loose, they are separated, and they should be touching/tight together.
The other thing is... Are you sure that the bolt is fully closed and locked when you chamber a round? On new guns, before they are broken it, it's not uncommon for the bolt to stop just short of full lock-up. When the trigger is pulled, the hammer motion is wasted when it strikes the back of the bolt carrier, and pushed the BCG the rest of the way to full lock instead of striking the head of the firing pin with full force. What you need to do to remove the FCG from the lower and check again to make sure that you have the springs in the right way, then take the gun to the range, and chamber a round. Hit the FA and make sure that the BCG is fully locked up before pulling the trigger. |
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From looking at the pics, it is hard to tell, but I would start with looking at possible machining tolerance issues. It looks like there is either a shadow, or the hammer/trigger pin holes are either oversized or oval in shape. A couple of other possibilities are the location of the hammer & trigger, being not properly located where the hammer could properly impact the firing pin. Also it is possible that the rear takedown pin & front pivot pin holes are out of proper location, as this may put the upper receiver assembly too far forward, where the hammer couldn't make proper contact with the firing pin. I would also gauge the firing pin protrusion to make sure it is within spec.
CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
| I think I will go with a new spring should I go stiffer or just with a normal stiffness? I might just get both and try it both ways. If it isn't the spring I have no idea what else it could be. When I completed the lower it was done exactly according the the manufactures specs. |
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Quoted:
My holes are not loose it take a good effort to put the pins in. This may be your problem. In the AR15 system, the hammer is typically a tight fit on the pins, and the pins themselves rotate in the receiver - look closely at your "good" aluminum lower as you move the hammer and trigger and you will see the pins rotating. If the pins are too tight in the receiver, the friction will likely retard the hammer fall badly and yield the problem you are seeing. |
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In your last pic, it looks like the hammer pin is not fully seated.
Is it possible the j-spring is binding on your pin, which you said has very tight fit in the receiver? Perhaps this is causing it to slow as it tries to rotate on the pin but meets resistance? If there's no impact marks on the hammer from striking the firing pin I can't guess as to whether it's striking at an angle, which would help diagnose slight out of battery or misplaced FCG holes... |
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Quoted:
This may be your problem. In the AR15 system, the hammer is typically a tight fit on the pins, and the pins themselves rotate in the receiver - look closely at your "good" aluminum lower as you move the hammer and trigger and you will see the pins rotating. If the pins are too tight in the receiver, the friction will likely retard the hammer fall badly and yield the problem you are seeing. Quoted:
Quoted:
My holes are not loose it take a good effort to put the pins in. This may be your problem. In the AR15 system, the hammer is typically a tight fit on the pins, and the pins themselves rotate in the receiver - look closely at your "good" aluminum lower as you move the hammer and trigger and you will see the pins rotating. If the pins are too tight in the receiver, the friction will likely retard the hammer fall badly and yield the problem you are seeing. After looking at this, they do still rotate with the hammer when the hammer is in motion. |
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Quoted:
Well good news it works!! I started looking into the hammer pin thinking it might be a little bound it and put some CLP in the hole and bam, she fires! Oh shit nvm on the last comment, good to hear brother! Let me know how that lower holds up. I'm thinking about gettin some 80 percent poly lowers if they hold up |
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