Ar Help!

[possum_128]

My Grandson has a lower that we built but has a problem. After he fires a round as he releases the trigger the gun fires again. I have pulled the trigger assembly out and replaced it back in to check proper installation and all seems correct. This does not happen with every shot but around every second or third shot it will double fire.

No sure what the problem is, any suggestions? Also who around indy is an ar armorer that could check it out? Thanks for any help.

 

[Leo]

If you have side to side slop in the hammer or trigger pivot, that will affect the sear surface engagement. It could also be a bad, trigger and or hammer machining. Not all AR parts are top quality. In that mechanism, as little as .010" out of spec can be unusable. I have seen a lower that was out of spec. Since there is nothing you can reliably do with the pivot pin holes, it was salvaged by using a one piece drop in trigger assembly. There are several aftermarket triggers on the market that are all in one assembly. Good luck

 

[tradertator]

Sounds like a disconnector issue.

 

[Cerberus]

Is the hammer spring in backwards? My BIL had the same issues until I corrected his backwards hammer spring.

 

[possum_128]

Is the hammer spring in backwards? My BIL had the same issues until I corrected his backwards hammer spring.

Nope. Checked and double checked, I thought that might be the proplem. I'm thinking the hammer or the trigger may be out of spec.

 

[rvb]

Assuming a GI-style trigger group?

The disconnect is releasing early; disconnector is releasing the hammer before the trigger has moved forward enough to catch it on the sear face of the trigger.

possible causes/solutions

1) Disconnect spring upside down. This spring (between trigger/disconnect) is funnel shaped and should be installed w/ the wide end in the trigger.

2) Out of spec holes on the receiver. Measure the spacing between the trigger/hammer holes. The specs are out there. I don't know them off the top of my head. This is probably the least likely, but can happen.

3) timing needs adjusted / tollerance stacking issue. You can adjust the disconnect to release the hammer later by filing the underside of the nose of the disconnect where it meets the trigger. a little goes a long way!

4) out of spec trigger group... replace with a new trigger group from a known good supplier, especially if the parts kit manufacturer is unknown or low-tier.

some reading....
http://books.google.com/books?id=6VJvMCNcu5oC&pg=PA171&lpg=PA171&dq=ar15+doubling+disconnector+timing&source=bl&ots=g9ztEbPB9f&sig=5VoBJfnL34xd0jTvgfFDh5K2twU&hl=en&sa=X&ei=3fo9UaS5B8aw2QXcjoCICw&ved=0CHIQ6AEwCA#v=onepage&q=ar15%20doubling%20disconnector%20timing&f=false

-rvb

 

[dukeboy_318]

My Grandson has a lower that we built but has a problem. After he fires a round as he releases the trigger the gun fires again. I have pulled the trigger assembly out and replaced it back in to check proper installation and all seems correct. This does not happen with every shot but around every second or third shot it will double fire.

No sure what the problem is, any suggestions? Also who around indy is an ar armorer that could check it out? Thanks for any help.

hammer spring or disconnector issue. Sounds like its bump firing. To help narrow it down, when he fires, make sure hes holding/pulling the trigger all the way back and letting it cycle fully before releasing pressure on the trigger. Sometimes if the spring is worn or is too light to begin with, not letting it cycle fully, will cause a bump fire.

 

[possum_128]

Assuming a GI-style trigger group?

The disconnect is releasing early; it is releasing the hammer before the trigger has moved forward enough to catch it on the sear face of the trigger.
May or may not be the case, it still at times will release the hammer even though the trigger is all the way forward.

possible causes/solutions

1) Disconnect spring upside down. This spring (between trigger/disconnect) is funnel shaped and should be installed w/ the wide end in the trigger.
Ruled this out, as stated I have checked and double checked all springs, they are installed correctly.

2) Out of spec holes on the receiver. Measure the spacing between the trigger/hammer holes. The specs are out there. I don't know them off the top of my head. This is probably the least likely, but can happen.

3) timing needs adjusted / tollerance stacking issue. You can adjust the disconnect to release the hammer later by filing the underside of the nose of the disconnect where it meets the trigger. a little goes a long way!

4) out of spec trigger group... replace with a new trigger group from a known good supplier, especially if the parts kit manufacturer is unknown or low-tier.

As for the rest all possible causes. I really would like someone who knows ar's better than I take a look at it, any suggestions?



some reading....
http://books.google.com/books?id=6V...e&q=ar15 doubling disconnector timing&f=false

-rvb

And thanks to all the responses everyone!

 

[possum_128]

hammer spring or disconnector issue. Sounds like its bump firing. To help narrow it down, when he fires, make sure hes holding/pulling the trigger all the way back and letting it cycle fully before releasing pressure on the trigger. Sometimes if the spring is worn or is too light to begin with, not letting it cycle fully, will cause a bump fire.

He is holding all the way back, checked this by me firing. So not a bump fire.

I have the lower broke down still after pulling the trigger and hammer out. After reinstalling them it will still sometimes release the hammer when releasing trigger manually about 4-5 times out of ten.

 

[rvb]

May or may not be the case, it still at times will release the hammer even though the trigger is all the way forward.

This doesn't make sense to me. It should be releasing the hammer the second time (the "double") as the trigger is on the way forward, not when it is all the way forward. If the later, as you described, it is not a disconnect issue and is definately a bad trigger/hammer interface. Replacement of parts is THE best solution in that case.

I really would like someone who knows ar's better than I take a look at it, any suggestions?

For much less $, you could buy a new trigger group from a name brand source and that would most likely fix the problem. Most of these issues are just the way the tollerances stack (on new parts) and by swapping parts the problem goes away... that's how most armors are going to solve the problem anyway. If you're feeling very cheap you could just get a new disconnector and start there.

-rvb

 

[possum_128]

This doesn't make sense to me. It should be releasing the hammer the second time (the "double") as the trigger is on the way forward, not when it is all the way forward. If the later, as you described, it is not a disconnect issue and is definately a bad trigger/hammer interface. Replacement of parts is THE best solution in that case.



For must less $, you could buy a new trigger group from a name brand source and that would most likely fix the problem. Most of these issues are just the way the tollerances stack (on new parts) and by swapping parts the problem goes away... that's how most armors are going to solve the problem anyway. If you're feeling very cheap you could just get a new disconnector and start there.

-rvb

I believe you are correct sir, I need to just buy a new trigger and hammer. I kind of was hoping for someone who knows their stuff could look at it and let me know for sure what I need to replace. Any suggestions on a good set that won't break the bank and if someone has them in stock around the Indy aera?

Not wanting to put 1-2 bills on this as the cost of the build was on me in the first place.

 

[rvb]

I believe you are correct sir, I need to just buy a new trigger and hammer and disconnector. I kind of was hoping for someone who knows their stuff could look at it and let me know for sure what I need to replace. Any suggestions on a good set that won't break the bank and if someone has them in stock around the Indy aera?

Not wanting to put 1-2 bills on this as the cost of the build was on me in the first place.

The trick these days is finding anything in stock.

A GI trigger group will not cost anwhere close to 1-2 hundred bucks. Maybe $75-ish if you go all Colt branded. Most other sources should be ~$35 for the whole trigger group. A disconnector alone should just be $4-$6.

You CAN spend $100-$300 if you go aftermarket specialty trigger (eg JP, Geisselle, AR-Gold, etc).

For a possible FREE solution, put the disconnect upside down in a vice and give the nose a couple swipes with a file and see if that helps. Hit w/ cold blue when done. (when checking the timing, I like to "bounce" the trigger forward... easy to do, hard to describe.... I let the trigger forward a smidge, then pull it right back. all in very tiny increments. I'm trying to MAKE it fall off the disco but miss the sear. if all I did was slowly ease it forward, I could be right on the edge of function and wear could cause failures relatively soon).

-rvb

 

[possum_128]

Thanks to all, I will check and see what is out there!

 

[dukeboy_318]

For much less $, you could buy a new trigger group from a name brand source and that would most likely fix the problem. Most of these issues are just the way the tollerances stack (on new parts) and by swapping parts the problem goes away... that's how most armors are going to solve the problem anyway. If you're feeling very cheap you could just get a new disconnector and start there.

-rvb

this^

 

[Hookeye]

What was the verdict on the disconnector spring?

 

[possum_128]

Talked to Mario at M&S, where we bought the kit. He said it was the disconnector so he mailed me a new one and spring. Will report if that takes care of the problem when it arrives. Thanks again everyone!

 

[possum_128]

Talked to Mario at M&S, where we bought the kit. He said it was the disconnector so he mailed me a new one and spring. Will report if that takes care of the problem when it arrives. Thanks again everyone!

Update. Received the new disconnector and spring in the mail from Mario and installed and it fixed the problem. A big +1 to Mario at M&S for great customer service.

 

[Leo]

Good deal. It is always nice when a solution is easy and inexpensive. Have a great shooting season.