I've got a dumb situation.  I say dumb because I'm sure it has a simple solution but I can't find it.  I assembled an AR with a Spikes receiver and a PSA AR15 Fire Control Group from Palmetto Part #7265.

The gun fires like a champ.  But only once.  It cycles properly but will not re-fire unless I switch to safety and then back to Fire each time.  The trigger is as frozen in place like the safety is on. Of course it only happens with live fire.  It dry fires fine but that's because it doesn't cycle then.   I'm sure this is something I did in the assembly, but I don't see it.

The other issue is I'm hoping someone knows for certain right off what I did wrong because the nature of Murphyland is I can only tell if the fix worked when at the range and actually firing.  I'm at least an hour one way for that.  That's a lot of back and forth trying this and trying that.

Can anyone help me? 

I’d think you could

1- dry fire,

2- hold the trigger

3- with trigger still held, cycle action via charging handle

4- release charging handle

5- release trigger. 

 

That shouod allow you to simulate live fire operations.

As it is now once the trigger is released it will not pull again even with hammer cocked in that cycle. 

Isn’t that usually the trigger spring in wrong?

Make sure your hammer spring is installed the right way.

This might help.  

 

 

 

The springs are correct by all accounts including the posted pictures and video (thanks).  I also have my Bushmaster side by side with the homebuild and everything "looks" proper.  I can say that compared to the Bushmaster the hammer on the Homebuild needs a hard push to lock into the disconnect whereas the Bushmaster requires very little pressure to do the same.  Is this a functional problem or just a quality difference? 

What bolt carrier do you have installed? Does it look the same as the one in your Bushmaster? Try swapping BCGs and see if you get the same results.

Better yet, swap entire uppers and see if you get the same results with the problematic lower.

37 minutes ago, BobA said:

The springs are correct by all accounts including the posted pictures and video (thanks).  I also have my Bushmaster side by side with the homebuild and everything "looks" proper.  I can say that compared to the Bushmaster the hammer on the Homebuild needs a hard push to lock into the disconnect whereas the Bushmaster requires very little pressure to do the same.  Is this a functional problem or just a quality difference? 

Check if the  grip screw is hitting the trigger.

I hope you can see these but there is a difference between them.  I bought the complete upper from Bushmaster so both are the same make.  One is for my 20" and the other is for my 16".  The bolt for the 16" is different however. Notice the cuts in the hammer slide.  I've equated this to the throw from the pressure being greater in the 20".  I assumed it needed more travel.

12 minutes ago, silverado427 said:

Check if the  grip screw is hitting the trigger.

That's a good one.  Give me 5mins.

3 minutes ago, BobA said:

That's a good one.  Give me 5mins.

Ok.  With the grip screw out the hammer catches on the disconnect much easier.  Could this have caused it? 

13 minutes ago, BobA said:

Ok.  With the grip screw out the hammer catches on the disconnect much easier.  Could this have caused it? 

It could if you were racking the charging handle along with flippling the safety back and forth. 

BAsically. the ar-15 trigger is single action. 

Normal cycle goes. 

rack it and cock the trigger and load a round. 

bang. 

BCG goes back and pushes the hammer onto the disconnect. 

BCG returns to battery loading another round 

release the trigger and the disconnect permits the hammer to engage the sear. 

Pull trigger to go bang and repeat. 

If the scre was impinging on the trigger, what you can get is 

rack it 

bang

BCG goes back and pushes the hammer onto the disconnect. 

BCG returns to battery and loads another round. 

releasing the trigger fails and the hammer binds on the disconnect due to the impingement. 

Fiddling with the safety nudges things enough to get the disconnect to unhook. 

bang. 

These are the JP instructions for fitting their basic trigger setup. They are a good read for understanding the AR  trigger and how change in fitment of bits can impact function and safety. 

https://jprifles.com/document_pdfs/JPFC_606.pdf

 

15 minutes ago, raz-0 said:

releasing the trigger fails and the hammer binds on the disconnect due to the impingement. 

Fiddling with the safety nudges things enough to get the disconnect to unhook. 

Sounds pretty logical.  I'll throw a washer on the bolt.  This is all good news.  The bad news is I was just at the range Sunday so the big test will have to wait a few days or at least to the weekend.  I'd still like to hear some more theories but I'll certainly let you all know the results.  Thanks all! 

33 minutes ago, BobA said:

I hope you can see these but there is a difference between them.  I bought the complete upper from Bushmaster so both are the same make.  One is for my 20" and the other is for my 16".  The bolt for the 16" is different however. Notice the cuts in the hammer slide.  I've equated this to the throw from the pressure being greater in the 20".  I assumed it needed more travel.

Just FYI:

There are different types of AR BCGs:

Depending on you LPK, the difference between your BCGs could cause an issue.

Sounds like thebgrip screw may be the culprit - but I’ve never seen an out of spec grip screw.

May be worth it to swap BCGs and see if you get different results.

Every grip screw I’ve seen has a Star washer on it. 

21 minutes ago, High Exposure said:

Just FYI:

There are different types of AR BCGs:

Depending on you LPK, the difference between your BCGs could cause an issue.

Sounds like thebgrip screw may be the culprit - but I’ve never seen an out of spec grip screw.

May be worth it to swap BCGs and see if you get different results.

It's my plan to bring both to the range with me as an experiment.  Can you point out the different advantages between my two?  They appear to be most similar to the top two pictured (SP1 - AR15 enhanced).  

But the screw could just be.  The entire gun wasn't a kit.  It's a basket case of pieces bought from here and there so ya never know.  

 

9 minutes ago, Displaced Texan said:

Every grip screw I’ve seen has a Star washer on it. 

It does.  I might add one for spacing.

You need the M16 carrier for full auto guns - the lug in the bag is what trips the auto sear.

I have heard of people having issues if they have certain hammers or disconnects and one of the bolts that have a bottom lug like the SP1 or the Enhanced AR.

AND THE WINNER IS!: @High Exposure !  I finally got to the range after everyone's great advice.  I brought my two different carriers and I was using the wrong one. I was using an M16 and it seems the AR Enhanced does the trick.  40 rounds without an issue.  Thanks!!