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Posted: 9/5/2012 4:01:33 PM EDT
| My dad had gotten a few things for his DPMS Bull 20 AR-15, but he'd been really busy and hadn't got a chance to do anything with it. First, I swapped out the factory pistol grip with a Magpul MIAD––no problems there. Next, I took the upper off the lower, removed the BCG and wrapped the FF handguard in paracord. After that, I installed an RRA two-stage trigger and that's where the problems started. After a couple of missteps, I got the lower to the point where it passed function test. I put the BCG back in the upper, mated the upper and lower together, and started function testing the two of them. I put it on fire, pulled the charging handle back, and then tried to dry fire it. Nothing. Trigger would not budge a bit. Frustrated, I decided we'd have to get somebody else to put in the 2-stage, so I took it out and put the factory FCG back in it, checked online to make sure I had it right, and then put the upper and lower together... same problem as the two stage. When the rifle's cocked, the trigger is completely locked up. What did I mess up? |
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Do you have the hammer spring behind the hammer so it pushes it forward? Does the lower function check without the upper receiver assembly on it?
CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
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Do you have the hammer spring behind the hammer so it pushes it forward? Does the lower function check without the upper receiver assembly on it? CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 I got that wrong the first time, but I've got the hammer spring the right direction now. And yes, it function tests correctly when it's not on the upper. |
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When the pistol grip was installed, it now protruded the head of the grip bolt into the bottom of the receiver void, and preventing the trigger from returning back to it's normal at home position to allow a disco release of the hammer.
So on that note, pull the FCG, install the grip, then mark the amount needed to be removed from the tip of the pistol grip bolt to flush it out with the the bottom of the receiver void (or slightly below, after you have confirmed that the grip bolt washer is in play). |
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Quoted:
When the pistol grip was installed, it now protruded the head of the grip bolt into the bottom of the receiver void, and preventing the trigger from returning back to it's normal at home position to allow a disco release of the hammer. So on that note, pull the FCG, install the grip, then mark the amount needed to be removed from the tip of the pistol grip bolt to flush it out with the the bottom of the receiver void (or slightly below, after you have confirmed that the grip bolt washer is in play). But does that hold water if it works when the lower is separated from the upper? He stated that it does. I really don't know... I'm just asking. |
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Quoted:
Quoted:
When the pistol grip was installed, it now protruded the head of the grip bolt into the bottom of the receiver void, and preventing the trigger from returning back to it's normal at home position to allow a disco release of the hammer. So on that note, pull the FCG, install the grip, then mark the amount needed to be removed from the tip of the pistol grip bolt to flush it out with the the bottom of the receiver void (or slightly below, after you have confirmed that the grip bolt washer is in play). But does that hold water if it works when the lower is separated from the upper? He stated that it does. I really don't know... I'm just asking. Yes, notice that he only states "got to to a point", meaning that he was forcing the trigger forward enough to get the disco to release the hammer. http://www.google.com/search?hl=en&q=rra%20nm%20two%20stage%20trigger&bav=on.2,or.r_gc.r_pw.r_qf.&biw=1024&bih=578&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=PK1JUIK2MrS20QGvr4EI It's either that, or the springs are not installed correctly (hundred samples in the above link, or he forgot to dry fit the FCG to the pins outside the receiver first to check for any side C channel burs on the trigger, and maybe even then forget to lube the part before they where installed as well. |
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Quoted:
Quoted:
Quoted:
When the pistol grip was installed, it now protruded the head of the grip bolt into the bottom of the receiver void, and preventing the trigger from returning back to it's normal at home position to allow a disco release of the hammer. So on that note, pull the FCG, install the grip, then mark the amount needed to be removed from the tip of the pistol grip bolt to flush it out with the the bottom of the receiver void (or slightly below, after you have confirmed that the grip bolt washer is in play). But does that hold water if it works when the lower is separated from the upper? He stated that it does. I really don't know... I'm just asking. Yes, notice that he only states "got to to a point", meaning that he was forcing the trigger forward enough to get the disco to release the hammer. http://www.google.com/search?hl=en&q=rra%20nm%20two%20stage%20trigger&bav=on.2,or.r_gc.r_pw.r_qf.&biw=1024&bih=578&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=PK1JUIK2MrS20QGvr4EI It's either that, or the springs are not installed correctly (hundred samples in the above link, or he forgot to dry fit the FCG to the pins outside the receiver first to check for any side C channel burs on the trigger, and maybe even then forget to lube the part before they where installed as well. No, I didn't dry fit the parts or check for burrs. Yes, I used lube. The hammer spring is definitely in correctly (the closed end against the front side of the hammer with the legs resting on the trigger pin) and I don't see any way for the trigger spring to go in wrong |
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Pull the FCG, and lets start from the beginning.
Selector installed, selector detent up in the channel, spring installed in the grip, install the pistol grip screw with spacer. Check the tip of the pistol grip screw to confirm that is is not protruding into the bottom of the receiver. Dry fit the trigger pin to the trigger outside the rifle, and if the pin rotates cleanly, then install the trigger with disco. Next install the hammer with the spring legs/coil on the bottom,and coming back. Now set the selector to fire, hold the trigger back, and cock the hammer back to the disco sear. Here is where the fun begins. With the trigger held all the way back, and hammer cocked to the rear trigger hook, is the disco/rear hook holding the hammer. If yes, put your hand in front of the hammer and release the trigger. The hammer should be release from the disco back hook, and the front hook of the trigger catching the hammer. Now with your hand in front of the hammer. pull the trigger, which should release the hammer from the trigger front hook. If any of the above is a crash and burn, then tell me what step, and we can go from there. Aldo to note, make sure that you have the right parts in play, and that you are not using parts from the standard FCG with the RRA trigger. |
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Pull the FCG, and lets start from the beginning. Selector installed, selector detent up in the channel, spring installed in the grip, install the pistol grip screw with spacer. Check the tip of the pistol grip screw to confirm that is is not protruding into the bottom of the receiver. There's at least a 1/4" of empty recess above the end of the screw. Dry fit the trigger pin to the trigger outside the rifle, and if the pin rotates cleanly, then install the trigger with disco.
Next install the hammer with the spring legs/coil on the bottom,and coming back. Now set the selector to fire, hold the trigger back, and cock the hammer back to the disco sear. I did all this. Here is where the fun begins.
With the trigger held all the way back, and hammer cocked to the rear trigger hook, is the disco/rear hook holding the hammer. If yes, put your hand in front of the hammer and release the trigger. The hammer should be release from the disco back hook, and the front hook of the trigger catching the hammer. Now with your hand in front of the hammer. pull the trigger, which should release the hammer from the trigger front hook. The trigger does all this just like you describe. If any of the above is a crash and burn, then tell me what step, and we can go from there. Aldo to note, make sure that you have the right parts in play, and that you are not using parts from the standard FCG with the RRA trigger.
Definitely have only the parts for the RRA 2-stage. Thank you for taking the time to help. |
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OK, we know that that the FCG is working, so when you go to cock the hammer, do so by pulling all the way back on the charging handle, then letting it go. If you try to walk the charging handle down, the bolt is not going to lock up correctly, and such can be seen by the gap between the front of the carrier and the face of the barrel extension.
So with the bolt allowed to run forward under it own power to lock up correctly, and not walked forward, if the trigger working correctly? |
| Post some detailed pictures of what you have. If things worked properly before you replaced the original trigger; then there are only a few things that can cause problems. The AR trigger is very simple by design and therefore generally very reliable. Your original trigger if reinstalled properly should work as it did before it was taken out. The RR trigger has (to some) a weakness but getting stuck is not it. For the records I put several thousand of rounds on one with no problems, once it was seasoned it turned out to be a good trigger. |
I realized something just now. The triggers have been working fine the entire time. I've been trying to dry fire the AR wrong like a bloody idiot. Did you know that an AR won't fire with the bolt locked back? A snippet of text from wikipedia boiled up to the front of my mind: "...fires from a closed bolt for accuracy..." "...fires from a closed bolt..." Then my mind went to the couple of times I tried it with the bolt forward and it worked.
I feel like hitting my head against a wall. |
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I realized something just now. The triggers have been working fine the entire time. I've been trying to dry fire the AR wrong like a bloody idiot. Did you know that an AR won't fire with the bolt locked back? A snippet of text from wikipedia boiled up to the front of my mind: "...fires from a closed bolt for accuracy..." "...fires from a closed bolt..." Then my mind went to the couple of times I tried it with the bolt forward and it worked.
I feel like hitting my head against a wall. Not a closed bolt gun is the world is going to drop the hammer on a bolt or slide locked back. Not sure what you have been playing with, but only a open bolt gun will release the entire B/C with a trigger pull to fire the weapon. About the only legal title 1 semi auto weapon that I know about is a an early Mac-10 open bolt gun. |
I've only been into shooting the last six months.
| Well... All I can do is chuckle about this one. While I commend you for taking this job on with so little knowledge, I must caution you that you really should have some idea of the mechanics behind something before you start taking it apart and changing things. I guess everyone has to start somewhere. Just be careful. These are not toys... A mistake with a firearm can cost someone their life... And then it's usually blamed on the firearm. |
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