Ar15 fires sometimes?

[Ryanheath27]

so I just built my first ar15.complete bear creek upper, aero lower, strike industries enhanced lower parts kit, and a ed2 trigger. I took it out for the first time today and the rifle will only fire sometimes. What I mean by that is it will shoot one or two rounds then the next round the bolt will stoke the primer and leave a dent but it's like the primer isn't igniting or something. I'm using American eagle 5.56 ammo. I do not know a ton about ar15s so don't beat me up too much on this if it's something simple lol.

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[bolus]

check the hammer spring to make sure it is not installed backwards. Common install mistake



oops, missed that you have an aftermarket trigger. I'm not familiar with that one but if it has a hammer spring similar to standard check its install position

 

[Bill W]

Could be s short firing pin protrusion from the bolt face.
Does the firing pin slide smoothly in and out the back of the bolt?
We all started at one point and learned .

 

[titsonritz]

check the hammer spring to make sure it is not installed backwards. Common install mistake

View attachment 462240

oops, missed that you have an aftermarket trigger. I'm not familiar with that one but if it has a hammer spring similar to standard check its install position

This the issue about 80% of the time.

What is an ED2 trigger, do you mean EDT2 by Hiperfire? If not please link.

 

[DirectDrive]

Could be s short firing pin protrusion from the bolt face.
Does the firing pin slide smoothly in and out the back of the bolt?
We all started at one point and learned .

Could be this ^^^
Firing pin protrusion –– Min. .028 Max. .036

Could be ammo, although American Eagle is very relliable

Could be that Hyperfire drop-in (if that's what you have)

Troubleshooting :
1) Check firing pin protrusion
2) Try a different FCG (trigger)
3) Try different ammo (least likely culprit)

 

[daved20319]

Possible dumb question, but that's my specialty, and you did say you're a newb to the AR . Did you take it apart, clean and lube, before heading to the range? AR's like to run wet, i.e. heavily lubed, and even more so with a new rifle. Good luck.

Dave

 

[11Charlie]

I say kudos for building your first and not buying it from a manufacturer! Once you get used to it, they are fairly simple but we all need help from time to time. Thats what we are here for, that and the great people.

My first guess would be the hammer spring. I had to watch a video six times to get my first one right. Second would be the firing pin.

Keep us posted!

 

[Joe13]

I'm guessing lube.

Total guess, but if the first couple shoot fine then that's enough to heat up your BCG and tighten things up in there preventing the firing pin from moving easily.

I'm a huge noob but I wanted to see if I was right or not lol.

 

[808hondacrguy]

I vote hammer spring backwards also, it is very easy to do, even if you are looking at the picture. Don't ask me how I know this,,,,,OK, been there, done that.

 

[11Charlie]

I vote hammer spring backwards also, it is very easy to do, even if you are looking at the picture. Don't ask me how I know this,,,,,OK, been there, done that.

I think we all have been there done that at least once!

 

[Caveman Jim]

Yep, BTDTBTTS....
But there are some here that believe that they were handed in AR as soon as they were out of the womb....

 

[HB of CJ]

Respectfully ...

Enough. This is a good example of not knowing what you do no know what you do not know what you must know. I have no idea what is wrong with your build, but if I had to guess based upon my great wisdom it would be the after market trigger AND the possibility of, (like already said) of the trigger spring being installed backwards.

Home builders must know what they are doing. There are areas of the build where experience is needed. Experience like just squeezing the trigger and letting the hammer smack your thumb to keep the hammer from pounding the bolt stop. Experience. You can instantly feel if the spring is installed correctly and has enough power.

BY ...How much that hammer snaps against your sore thumb. OUCH! We will not talk about other areas of the home build which must be done correctly. Not the way some Internet video tells you. Like just knowing by feel if your firing pin extends out enough. How much pokes out from the bolt head. By feel alone. Or front lower detent pins done in 5 seconds.

Front lower receiver take down detent pins can fly quite a distance. Amazing hang times. Lost forever in the shag carpet. A cheap very thin clothing dry cleaning bag works great as a containment force field. Fling flying small AR15 parts. A very thin expedient knife blade works perfectly to install those pesky detents.

Oh ... forgetting the firing pin during a final build assembly. Embarrassing. Do not ask how I know this to be true. Also ... roll pins and broken lower receivers. $OUCH$. Again ... do not ask. We all start from nothing to experienced at some point. And ... we will all make beginners mistakes. Sometimes a big deal.

LIKE ... Long ago the new guy broke a rebuild-able M16 lower receiver due to an incorrect way of installing that really pesky trigger guard roll pin. The arse chewing was incredible. The required paperwork was extreme.

AND ... How much to shave the front upper receiver flat to exactly torque up properly that pesky barrel to 42 pounds. Or ... how much to shim that barrel to get the OEM irons exactly correct with the rear aperture EXACTLY centered with the bullet holes being EXACTLY centered at 100 yards. Knowing where ALL the potholes are will eventually come to you.

Respectfully.

Hundreds of AR15 builds. Uncounted many M16 rebuilds. Long ago, far away. Are I getting old yet?

 

[Mygrainman]

...

Front lower receiver take down detent pins can fly quite a distance. Amazing hang times. Lost forever in the shag carpet.

I believe they create a rift in space time and warp into a separate demention. Such a rift also exists in the laundry but only takes one of each of my socks. There is a parrellel world out there covered in Takedown detents, socks, and 1/2" wrenches and sockets.

 

[titsonritz]

Front lower receiver take down detent pins can fly quite a distance. Amazing hang times. Lost forever in the shag carpet. A cheap very thin clothing dry cleaning bag works great as a containment force field. Fling flying small AR15 parts. A very thin expedient knife blade works perfectly to install those pesky detends.

Or you use the correct tool to do a proper install and not worry about launching the detent and spring.
https://www.brownells.com/gunsmith-...t-pin-detent-installation-tool-prod26488.aspx

 

[titsonritz]

If the trigger is indeed a Hiperfire EDT2 trigger (GI style) and not a cassette style trigger, the smart money is an incorrectly installed hammer spring. The model also comes with two springs, which did you use? I would always use the heavy spring (which for the EDT2 is red).

I don't buy the firing pin protrusion as being an issue since this is a new upper. Firing pins are usually worn from use to cause this malfunction. Could it be a batch of short firing pins? Possible but unlikely.

I don't buy the lube theory either, here's why. The primer was dented, this indicated a light strike. If the weapon was not lubed to the point that it would not into battery then there would be no mark on the primer as the rotating bolt design will not allow the firing pin to protrude from the bolt when it is out of battery.

If the hammer spring is the full strength version and installed correctly my money would be on an out of spec lower receiver, specifically, the hammer and trigger pin holes are not in proper relation to one another.

 

[Kruel J]

Hammer spring. I've done it. Same results as the OP. It happens to even guys like me that have built MANY AR's.

 

[titsonritz]

Hammer spring. I've done it. Same results as the OP. It happens to even guys like me that have built MANY AR's.

Easy to do...

This video may help:

 

[DirectDrive]

If the trigger is indeed a Hiperfire EDT2 trigger (GI style) and not a cassette style trigger, the smart money is an incorrectly installed hammer spring. The model also comes with two springs, which did you use? I would always use the heavy spring (which for the EDT2 is red).

I don't buy the firing pin protrusion as being an issue since this is a new upper. Firing pins are usually worn from use to cause this malfunction. Could it be a batch of short firing pins? Possible but unlikely.

I don't buy the lube theory either, here's why. The primer was dented, this indicated a light strike. If the weapon was not lubed to the point that it would not into battery then there would be no mark on the primer as the rotating bolt design will not allow the firing pin to protrude from the bolt when it is out of battery.

If the hammer spring is the full strength version and installed correctly my money would be on an out of spec lower receiver, specifically, the hammer and trigger pin holes are not in proper relation to one another.

OK, as the clues come in, if this is a conventional trigger and not a cassette, Number 1 cause for this type of malfunction (in a new build) is incorrect spring installation.
When I saw "Hyperfire" I assumed drop-in cassette (which have self-contained springs).
Check your springs for proper installation.
See here :

 

[titsonritz]

OK, as the clues come in, if this is a conventional trigger and not a cassette, Number 1 cause for this type of malfunction is incorrect spring installation.
When I saw "Hyperfire" I assumed drop-in cassette (which have self-contained springs).
Check your springs for proper installation.

The OP never mentioned Hiperfire, that was my inquiry about the ED2 trigger he stated and still has not confirmed at this point. I just surmised it based on the similar named EDT2 which I knew to be a standard GI configuration rather than the cassette style they are famous for. Again all speculation.

 

[DirectDrive]

The OP never mentioned Hiperfire, that was my inquiry about the ED2 trigger he stated and still has not confirmed at this point. I just surmised it based on the similar named EDT2 which I knew to be a standard GI configuration rather than the cassette style they are famous for. Again all speculation.

I googled the part number and saw Hyperfire

"Solving AR issues with as little information as possible."