Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
BCM
User Panel

Page AR-15 » Troubleshooting
AR Sponsor: bravocompany
Site Notices
Posted: 1/6/2011 1:39:22 PM EDT
This is my first AR build and I have run into a problem.  I bought a complete 20" HBAR upper from Model 1 Sales a couple of years ago that I have used with my S&W lower and it works great.  About 6 months ago, I purchased a stripped Aero Precision lower at a gun show.  Recently I purchased a Colt Stainless LPK and Model 1 A2 buttstock.  I assembled the lower and started my function checks.  When I cock the hammer it catches and makes an audible click and functions fine. I will call this position #1.  However I noticed that the disconnector is not actually holding the hammer back in position #1.  It seems like there is a lip or something on the front of the trigger  that is catching the hammer.  If i push the hammer down more I hear and feel another click and the disconnector is holding the hammer back.  We'll call this position #2.  When I try the function check the disconnector will not release the hammer.  I have to take a punch and push down on the rear of the disconnector.  It then releases the hammer to position #1 and it will now release the hammer.  When I mate the two receiver halves and pull back on the charging handle, all is fine.  But this places the hammer into position #2 and it will not dry fire.  All other aspects of the function check works great (loading, extraction, ejection, safety, mag release, bolt catch).  I cannot seem to figure it out.  I have taken it apart and reassembled it to no avail.  I also loosened the grip screw thinking maybe it was somehow impinging on the trigger.  No change.  Sorry if this has already been addressed, but i searched and didn't find anything.  Thanks in advance and if there is anything I can explain better, please let me know.  

Once again,

Model 1 20" Upper
Aero Precision Lower
Colt Stainless LPK
DPMS pistol grip
Model 1 A2 Buttstock
Link Posted: 1/6/2011 2:42:47 PM EDT
[#1]
Make sure the disconnector spring has the bigger end down inside the trigger not on top. Also make sure the trigger and hammer springs are installed correctly.
Link Posted: 1/6/2011 3:10:00 PM EDT
[#2]
I did have the hammer spring on backwards at first, but that was remedied on the reassembly.  Also double checked the disconnector spring and it is installed properly.  Just removed the safety to see if the trigger was somehow catching up on it and it didn't remedy the situation.  I guess I will disassemble it again and try one more time.
Link Posted: 1/6/2011 3:19:38 PM EDT
[#3]
Link Posted: 1/7/2011 7:43:21 PM EDT
[#4]
I just had that problem on this sunday with my Nephew new build and what it was is the Disconector had a small bur that would not let the disconector let go of the hammer to get on the trigger step off and with a small file it was solved... Check yours by using a small screwdriver manually with the hammer locked down and see if the disconector lets it go when its pushed down... If not I would take out the trigger and Hammer and make sure you reinstall it correctly if you didnt do it in the frist place..... and also in the picture you supplied the safety dosent look like its all the way pointing up towards the fire position.....
Link Posted: 1/8/2011 5:46:19 AM EDT
[#5]
Quoted:
OK, out the gate there are two FCG sizes,

The mil spec size is .154 hole sizes, and the older colt large pin size is .174.

Chances are you lower is the .154 size, that is the pin and FCG hole size you should be using, and not the larger .174 unit.

Next before you install the parts, make sure that they are lubed, and pins will freely rotate (just not a lot of slop) on the parts outside the rifle.  In the case of the trigger, the side C cuts may have burs, and cause the pin to bind up on it (will not freely rotate).  Also, before installing the parts, run your finger down the both the disco and back of sear edges for milling burs (would prevent a clean release). If found, then use a stone and remove them.

Now onto the install of the parts,

As stated, disco spring gets installed large coil down into the back of the trigger slot, and this should cover the rest.

http://www.ar15.com/content/guides/assembly/lower/
http://img.photobucket.com/albums/v503/AR15forme/IMG_5660.jpg



and the older colt large pin size is .170  

Link Posted: 1/8/2011 7:22:03 AM EDT
[#6]
Quoted:
I just had that problem on this sunday with my Nephew new build and what it was is the Disconector had a small bur that would not let the disconector let go of the hammer to get on the trigger step off and with a small file it was solved... Check yours by using a small screwdriver manually with the hammer locked down and see if the disconector lets it go when its pushed down... If not I would take out the trigger and Hammer and make sure you reinstall it correctly if you didnt do it in the frist place..... and also in the picture you supplied the safety dosent look like its all the way pointing up towards the fire position.....


I have been able to release the hammer when I press down on the disconnector with a small punch, so I will inspect the disconnector for burrs again.  Visually when I checked it before I could not see any burrs, but I will check it again and lightly file it to see if that helps.  Also that is not my picture that is posted.  Another thing:  the safety selector is very difficult to get into the receiver.  I got it in on the first install after just messing with it for about 20 minutes and it functioned fine.  However, I have not been able to get it to go back in the receiver.  It seems to be getting hung up on the rear of the trigger.  On my Smith and Wesson that I bought, the safety falls out and slides in freely when the detent is removed (when I changed the grip).  Any Ideas?
Link Posted: 1/8/2011 7:39:29 AM EDT
[#7]
Had that problem. Replaced the safety selector and problem solved.



Try to release the hammer with the safety removed. Then try another safety selector if you have a spare


 
Link Posted: 1/8/2011 7:50:56 AM EDT
[#8]
well, i went and ran over all the surfaces with a stone and polished them up a bit, and it didnt solve anything.  still unable to get the disconnector to release the hammer.  I still have to push the rear of the discon with a punch to release it.   I am very hesitant to remove any more material, because I do not want to create an unsafe working condition within the rifle.  I may have to try to find a gunsmith and have them look at it.  This is my first build, and I would rather be safe than sorry, especially since I will not be the only one using the rifle.  Anyone know any good gunsmiths around the Cincinnati, Ohio area?


Also to the last post, I do not have a spare safety selector, unless I want to remove the one from the factory rifle I have.  Which I really do not want to do.  I may just purchase another one and see if that works.

Thanks everyone for the input.  If anyone can think of anything else I can do, please chime in.  Keep in mind I have no gunsmithing experience beyond the assembly of this rifle, so I am quite a n00b...




Link Posted: 1/8/2011 10:30:47 AM EDT
[#9]
If Im not mistaken you cant get the safety in unless you have the hammer cocked but Id try using the other safety from the other rifle and see if its not this safety is out of spec... Inspect all the parts for burrs and polish lightly if you feel any also like so many are telling you make sure you installing the springs correctly and also the detents since some have a point and some dont.  On my Spikes I had to cut the spring for the safety detent two coils in order for my ambi safety work correctly.  Take a pic of your setup and put it up here and Im sorry I didnt read the post with the pic good enough to understand it was not yours but the safety is not all the way up in it anyways.....
Link Posted: 1/8/2011 5:50:34 PM EDT
[#10]
Link Posted: 1/27/2011 8:29:40 AM EDT
[#11]
I had this issue recently and gave up and got another FCG to fix the issue only because I didn't have a camera. I completely stripped the lower like 5-6 times trying to figure out the malfuntion. I have seen most of these trigger reset issues cleared up here with a pic oddly enough lol. Funny how we all swear up and down everything is on right only to find it's usually some simple spring on backwards eh lol. My new FCG works without issues though so go figure.
Link Posted: 1/27/2011 3:20:29 PM EDT
[#12]
Recently I purchased a Colt Stainless LPK

Colt does not make a SS LPK.  Where did this come from?
Link Posted: 1/30/2011 5:56:53 AM EDT
[#13]
The so-called position #2 shouldn't exist at all unless the trigger is pulled and held back, that's the job of the disconnector, is to catch the hammer and prevent hammer following when the trigger is held back.  Your disconnector timing is way too early and probably caused by either bad trigger components (out of spec) or receiver out of spec. Normal in-spec components (receiver/fire control group) would not have the issue above, however, sometime these parts do get through Q-C so you can either fine tune them to work together or get new ones.

Since you have another receiver with working trigger group, why not take out that trigger group and install in this new lower, if the S&W  trigger group works in your new Aero lower, then it is your new trigger group, perhaps the trigger itself is out of spec with a high trigger tail (thus explained why it is hard for you to remove the safety) If the S&W trigger group exhibits the same problem then it is your new receiver being out of spec.  Either case, return the defective parts.

With that said, you can fix it if so incline. First need to check see if the trigger functions correctly take the disconnector out, test the trigger for release and sear re-engagement.  Be sure to do this with your thumb on the the hammer to prevent it from whacking the receiver. If the trigger function is ok then you can re-time the disconnector by gently filing its tip to clear the rear surface of the hammer when simply pushing down on the hammer (as you were doing to create position #2).  Remember the only time the disconnector need to engage the hammer is when you pull the trigger and hold it back while recocking the hammer.  Go slow, it doesn't take much to time the disconnector. If you go too far then the hammer will follow the bolt after firing and render the weapon unsafe. Good thing is that a new disconnector is only a few bucks.



Link Posted: 1/30/2011 9:44:58 AM EDT
[#14]
Quoted:
I assembled the lower and started my function checks.  When I cock the hammer it catches and makes an audible click and functions fine. I will call this position #1.  However I noticed that the disconnector is not actually holding the hammer back in position #1.  It seems like there is a lip or something on the front of the trigger  that is catching the hammer.  This is normal FCG opertation. The disconnecter doesn't hold the hammer in place when it is cocked and your finger is off the trigger. The hammer has a notch on the bottom for the front end of the trigger to sit in. When you squeeze the trigger, the front edge (sitting in the notch of the hammer) moves downward allowing the hammer to snap forward striking the firing pin. The only time the disconnecter is engaged is when you hold the trigger in the rear position allowing the BCG to re-cock the hammer. Once you let go of the trigger, the disconnecter will release the hammer and it is then caught by the front end of the trigger (in the notch) locking it back in place all over again. Hope this helps. And Good Luck

PS- There are some good videos of FCG operation on Brownells website.


If i push the hammer down more I hear and feel another click and the disconnector is holding the hammer back.  We'll call this position #2.  
Is you finger off the trigger? When I try the function check the disconnector will not release the hammer. I have to take a punch and push down on the rear of the disconnector.  It then releases the hammer to position #1 and it will now release the hammer.  When I mate the two receiver halves and pull back on the charging handle, all is fine.  But this places the hammer into position #2 and it will not dry fire. Make sure you didn't confuse the disconnecter spring with the bolt catch spring. The disconnecter spring is flared out on one end. (Kinda looks like a mushroom). Its installed big-side down.

All other aspects of the function check works great (loading, extraction, ejection, safety, mag release, bolt catch).  I cannot seem to figure it out.  I have taken it apart and reassembled it to no avail.  I also loosened the grip screw thinking maybe it was somehow impinging on the trigger.  No change.  Sorry if this has already been addressed, but i searched and didn't find anything.  Thanks in advance and if there is anything I can explain better, please let me know.  

Once again,

Model 1 20" Upper
Aero Precision Lower
Colt Stainless LPK
DPMS pistol grip
Model 1 A2 Buttstock


Page AR-15 » Troubleshooting
AR Sponsor: bravocompany
Close Join Our Mail List to Stay Up To Date! Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.


By signing up you agree to our User Agreement. *Must have a registered ARFCOM account to win.
Top Top