AR15 short stroking

[Capbyrd]

A friend asked me to take a look at his AR.  He didn't know the terminology so just jam and misfire were all I had to go on.   After a range trip, failure to feed was the issue and I guessed that it was likely short stroking.   I started with cleaning and that made no difference.  I took it back to the workbench and started looking things over and discovered this.  
 

 

It was hidden by the way that the two piece rail mounts over the hand guard cap.  It has apparently been like this for a while too because the erosion on the gas port in the block was terrible. 
 

 

 

Luckily, he had already purchased a replacement gas block and tube so I went ahead and replaced both.  I haven't taken it back out for testing yet but I'm pretty sure that I couldn't have possibly made it worse.  





Yall check your gas blocks!!!

[Prod951]

Things I would check. 

1. Check gas key. I sold a perfect spikes NiB that had a broken bolt that would short stroke.

2. Check gas rings.

3. Check buffer spring.

 

Base on the condition of the barrel and gas block I would change check just in case.

[Capbyrd]

35 minutes ago, Prod951 said:

Things I would check. 

1. Check gas key. I sold a perfect spikes NiB that had a broken bolt that would short stroke.

2. Check gas rings.

3. Check buffer spring.

 

Base on the condition of the barrel and gas block I would change check just in case.

I used spare parts from other rifles to rule all of that out.   The buffer and spring are being replaced anyways because they are beat and I'm not even sure the spring is correct.  Two different BCG's acted the same.  

He's been throwing money at it trying to solve it but no one ever looked at the gas block alignment. 

  

Edited April 20, 2020 by Capbyrd

[Prod951]

Replace the gas block and tube. Buts also possible the gas port on the barrel is bad just from general wear.

[Prod951]

Not to mention that looks like one of those Chinese clamp on blocks. Its highly possible it was out of spec from the jump. Let your friend know you really get what you pay for in the gun world.

Edited April 20, 2020 by Prod951

[asu174]

3 hours ago, Prod951 said:

Not to mention that looks like one of those Chinese clamp on blocks. Its highly possible it was out of spec from the jump. Let your friend know you really get what you pay for in the gun world.

My first thought.  I already don’t love set screw gas blocks, let alone this clamp style.  

[Prod951]

On 4/20/2020 at 3:55 PM, asu174 said:

My first thought.  I already don’t love set screw gas blocks, let alone this clamp style.  

Let's us know how it goes after you do the block and the tube.

[Capbyrd]

12 minutes ago, Prod951 said:

Let's us know how it goes after you do the block and the tube.

I already installed them.  Before the first post.  Thought I said that.   I just need a day I’m not working to get to the range. 

[Prod951]

Did it work?

[Capbyrd]

So I made it to the range Friday and the rifle is functioning flawlessly now.   So like I said in the first post, check your gas blocks!