AR15.Com Archives
 Help with Hammer getting stuck and not releasing.
EXPcustom  [Member]
7/29/2006 3:13:02 PM EST
I have attached pics to better explain the problem. I assembled the Ar with the DPMS parts kit and use a high quality 80% reciever. My problem is when you pull the hammer back it catches on the bottom of the trigger then connects on the top of the disconnector. It the wont release.
If I pull the hammer just until it catches the bottom of the hammer on the trigger it will fire every time. I then put the upper assmebly on pull the charging handle back and it pulls the hammer back too far and it will not release.
I put the green diamond around the piece that catches and fires each time and a red circle around where the hammer catches and it will not release on the disconnector.

I am a newbie and this is my first build by the way and yes the safety is off.

*Edited to remove pics I need the space for my Ebay items sorry,
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grizzlyarms  [Team Member]
7/29/2006 3:21:30 PM EST
either the LPK is out of spec, (doubtful) or your holes for the hammer and/or trigger are off. you may need to weld and re-drill.


BTW, what kind of finish did you use on the lower? it is very black. i like it.
EXPcustom  [Member]
7/29/2006 3:33:59 PM EST
Thanks, The finish is the Brownells Matte Black bake on finish. I did notice even after baking it chips easy on this forged aluminum reciever so I used a black sharpie to cover the paint flaws see if you can see them in the photo.

My question is can I use my dremel and shave the top pat of the disconnector so it is to spec?

Also my other question is is it supposed to catch there at the top disconnector or only the bottom of the trigger?
Archer1122  [Team Member]
7/29/2006 3:53:43 PM EST
Does it pass the function check? The hammer should catch the disconnect until you let pressure off the trigger and then it releases. If it didn't catch it would go FA. Check the funtion test in the sticky's. Go to the information tab up top and then click on "guides" everything you need to know is there,more info than you'd get from a manual.
EXPcustom  [Member]
7/29/2006 3:57:16 PM EST
Regarding the function test. I hold the trigger down keep holding it while pulling the hammer back it goes all the way back catches then I let go of the trigger and the hammer is still stuck. Its seams to be holding on by barely a micro meter on the top of the disconnector that is why I keep thinking if I just shaved the edge of it with a dremel?
EXPcustom  [Member]
7/29/2006 4:03:42 PM EST
Maybe my trigger is unuable to come down far enough to release the hammer. My thought was also to shave the very front part of the trigger so it can tilt a little further?
sdf1  [Member]
7/29/2006 5:43:39 PM EST
Something seams to be out of spec.As yor release the trigger you should see the hammer moving foward release from the secondary sear and fall on the primary.an angle may be a little off.I would play with the secondary too to see if I could fix this, plus it a little cheeper to replace if all goes wrong.
sdf1  [Member]
7/29/2006 5:57:33 PM EST
Didn't see this before

"Maybe my trigger is unuable to come down far enough to release the hammer. My thought was also to shave the very front part of the trigger so it can tilt a little further?"

If you mean the stoned and very shiny front section which is angled I wouldn't mess with it unless absoloutly necessary as this is the primary sear surface and the wrong angle could make the gun double tap with a singe trigger pull.
grizzlyarms  [Team Member]
7/29/2006 6:32:13 PM EST

Originally Posted By EXPcustom:
Regarding the function test. I hold the trigger down keep holding it while pulling the hammer back it goes all the way back catches then I let go of the trigger and the hammer is still stuck. Its seams to be holding on by barely a micro meter on the top of the disconnector that is why I keep thinking if I just shaved the edge of it with a dremel?



if it is that small of an amount i say Dremel time!!!

just remember to polish it good when you're done. i would probably file on the hammer though rather than the disconnector. and make sure you only file the top to "shorten" the total length of the hammer. do not round the contact surfaces. don't overdo it or it will start to slamfire on you.

remember if it double taps or slamfires at the range and the ATF spy catches you, it would be really hard to defend a "malfunction" after you filed down the hammer or disconnector.
river_rat  [Member]
7/29/2006 7:15:31 PM EST
I had a similar problem with one of my AR's. When working up loads it occurred. When I would get close to max the disconnect would not release the hammer. Sometimes if I pulled the trigger again it would work. Opened it up and tried slamming the hammer back with the side of my palm with the trigger depressed. Sure enough if I did it hard enough i could reproduce the problem. It turned out that the spur on the hammer was hitting the disconnect and jamming it. Identified by a small shiny spot where it hit. Removed some metal off the tip of the spur and haven't had a problem since. On a side note it was also a DPMS LPK.
EXPcustom  [Member]
7/29/2006 7:26:55 PM EST
I have some spare parts I tried filing down part of the trigger at the bottom front so it would get a little more tilt that did not work. So what would be the place to dremel a little? I circled the two areas I thought please help I dont want it to burst or full auto on me.

If its a different area I need to dremel let me know.

Also the FCG in a functioning AR the trigger when depressed should push down on the hammer and get it to release correct, I was never sure of this. I know the hammer locks at the bottom first then the top according to the manuals I read.

Also forgive my ignorance but what the hell does that pin inside the hammer do? I have not messed with it at all and I was wondering if thats the problem?
river_rat  [Member]
7/29/2006 7:36:14 PM EST
Did you try what I suggested? If so and that is it you want to remove metal off the claw part of the hammer. Try .030" to .050" first. i don't think it is the engagement sufaces that are the problem. I really think it is the claw hitting and jamming the disconnect. Someone else had the same problem I had and it worked for them. Your problem sounds real similar.
NimmerMehr  [Member]
7/29/2006 8:01:15 PM EST

Originally Posted By EXPcustom:
I have some spare parts I tried filing down part of the trigger at the bottom front so it would get a little more tilt that did not work. So what would be the place to dremel a little? I circled the two areas I thought please help I dont want it to burst or full auto on me.

If its a different area I need to dremel let me know.

Also the FCG in a functioning AR the trigger when depressed should push down on the hammer and get it to release correct, I was never sure of this. I know the hammer locks at the bottom first then the top according to the manuals I read.

Also forgive my ignorance but what the hell does that pin inside the hammer do? I have not messed with it at all and I was wondering if thats the problem?

home.comcast.net/~mrdjenmd/lowerKithelp.GIF


The areas you circled on the hammer and disconector is what stops the hammer from going forward (i.e. following the bolt carrier when it goes forward) and firing more than one round when you hold down the trigger. I would not alter either one without first understanding the mechanical and legal ramifications of doing so.

Edit: The pin in the hammer? The J pin? It mates with the grove in the hammer pin to keep the hammer centered with the fireing pin.
EXPcustom  [Member]
7/29/2006 9:37:07 PM EST
River rat I followd you suggestion and slowly dremeled the claw part of the hammer. Checked it and dremmeled some more till the claw part of the hammer does not even catch the trigger anymore, it only catchs at the disconnector now so when I pull the trigger you can see the entire trigger move and disconnector spring but the hammer as well as the disconnector stay stationary still. I really thought it would work. I dont see the hammer catching anywhere else on the disconector or the trigger. Good thing I have an extra parts kit because I knew I would burn a few extra parts :)
river_rat  [Member]
7/29/2006 9:53:14 PM EST

Originally Posted By EXPcustom:
River rat I followd you suggestion and slowly dremeled the claw part of the hammer. Checked it and dremmeled some more till the claw part of the hammer does not even catch the trigger anymore, it only catchs at the disconnector now so when I pull the trigger you can see the entire trigger move and disconnector spring but the hammer as well as the disconnector stay stationary still. I really thought it would work. I dont see the hammer catching anywhere else on the disconector or the trigger. Good thing I have an extra parts kit because I knew I would burn a few extra parts :)


If you ground off the right part then it is more than the hammer jamming the disconnect. It is quite possible that the hammer or trigger pin holes are incorrect on location. Grinding where I stated will not affect the correct function of the FCG. All it will do is provide clearance and make the hammer slightly lighter. So unless you just got an entirely bad LPK the trigger and hammer will function correctly.

Do you have another lower? If so try that FCG in it and see if it functions correctly. If it does then I would suspect that the trigger/hammer pin holes are off.
river_rat  [Member]
7/29/2006 10:12:48 PM EST
EXPcustom check your IM.
EXPcustom  [Member]
7/30/2006 12:21:57 AM EST
It was the rear part of the hammer I dremeled still no luck. You know it does look as though that Baxter Jig they sell on AR15plus.com is not that accurate. I already ordered one from CNCgunsmithing and will keep you guys updated on what happens. My 80% recievers are nice the HPS forged ones I got from them. I also got a CMX ceramic one that was not that great from them. To bad KT does not have any right now.

If anyone has any suggestions or I am moving on to my next reciever blank?
Kooter  [Team Member]
8/1/2006 12:11:01 PM EST
Did you install the disconnector spring upside down?
EXPcustom  [Member]
8/1/2006 1:18:06 PM EST
By the way thanks for the help and in case you are wondering this is what happened. I drilled the pistol grip hole incorrectly so I JB welded it redrilled it and tapped it. I had a small mound of JB weld that got inside the reciever and I mean less than a Milimeter. I dremeled it smooth and now the gun fires without fail.

One last qustion just to make sure everythings OK when I pull back the hammer it should catch on the bottom not at the top where the disconnector is correct? I can pull the hammer back and it will not catch at the top and I did a fire and safety check and everything functions fine. My only concern is that it does not full auto on me.

The reason I checked is another member said in the other thread his pistol grip screw went to high into the reciever and he had to use extra washers to space it properly.
NimmerMehr  [Member]
8/1/2006 2:08:51 PM EST

Originally Posted By EXPcustom:
One last qustion just to make sure everythings OK when I pull back the hammer it should catch on the bottom not at the top where the disconnector is correct? I can pull the hammer back and it will not catch at the top and I did a fire and safety check and everything functions fine. My only concern is that it does not full auto on me.


Function check your rifle!
ar15.com/content/guides/functionCheck/

(Note: if you do not have an upper on the lower, do not let the hammer strike the receiver!)

* THE FOLLOWING CHECKS ARE PERFORMED ON UNLOADED RIFLES *

SAFE
Pull the charging handle to the rear and release. Place the selector on SAFE. Pull the trigger, and the hammer should not fall.

SEMI
Place the selector on SEMI. Pull the trigger and hold to the rear. The hammer should fall. Continue to hold the trigger to the rear, pull the charging handle to the rear, and release it, release the trigger with a slow, smooth motion until the trigger is fully forward. The hammer should not fall. Pull the trigger. The hammer should fall.


Edit:

In semi mode when the bolt carrier moves back during reload and the user is depressing the trigger, the BC cocks the hammer and also pushes the hammer down to the point that the hammer and disconnector latch. When the bolt carrier moves forward back into battery, it of course no longer pushs down on the hammer, but the user is still depressing the trigger, so the disconnector and hammer stay latched. (This is what prevents a runaway in semi mode) When the user releases the trigger, the disconnector and hammer disengage, the hammer moves forward towards the fireing pin, but is stopped by the hammer engaging the trigger. When the user depresses the trigger again, the trigger then breaks contact with the hammer, the hammer goes forward and hits the fireing pin.
EXPcustom  [Member]
8/1/2006 2:20:40 PM EST

Originally Posted By NimmerMehr:

Originally Posted By EXPcustom:
One last qustion just to make sure everythings OK when I pull back the hammer it should catch on the bottom not at the top where the disconnector is correct? I can pull the hammer back and it will not catch at the top and I did a fire and safety check and everything functions fine. My only concern is that it does not full auto on me.


Function check your rifle!
ar15.com/content/guides/functionCheck/

(Note: if you do not have an upper on the lower, do not let the hammer strike the receiver!)

* THE FOLLOWING CHECKS ARE PERFORMED ON UNLOADED RIFLES *

SAFE
Pull the charging handle to the rear and release. Place the selector on SAFE. Pull the trigger, and the hammer should not fall.

SEMI
Place the selector on SEMI. Pull the trigger and hold to the rear. The hammer should fall. Continue to hold the trigger to the rear, pull the charging handle to the rear, and release it, release the trigger with a slow, smooth motion until the trigger is fully forward. The hammer should not fall. Pull the trigger. The hammer should fall.


Worked perfecto!!!!! Thanks.

Just so you guys know it was a 80% HPS forged reciever from AR15plus.com and it works great, also the HPS forged reciever they have no is very high quality nice and straight. I heard bad things about their first few batches.
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