Measure the damn gas port hole on the barrel.  If it is short stroking with a carbine weight buffer, it's likely going to short stroke with a rifle weight buffer. 

If the barrel was intended for a soft shooting set up, it may be undersized and expect you to have a lightened carrier and reduced weight buffer. 

For example a nordic components 18" barrel ships with an undersized gas port for that reason. 

If it's small you have two choices. Lightened components or drill it out. 

 

If you (or someone you know) can get dealer pricing from brownells their in house lightened one is cheap. $80 ($125 if you have to pay retail). 

https://www.brownells.com/rifle-parts/bolt-parts/bolt-carrier-groups/m16-5-56-lightweight-bolt-carrier-group-prod116267.aspx

 

@JohnnyB Did you resolve the issue yet?

I had a problem similar to this once.. and I used a very similar way to line up the gas block.. guess what.. it was misaligned.. 

I came up with a really ghetto way to line up the gas block.. it works perfectly 100% of the time.. but you have to be careful.. 

• take a piece of soft solder that fits in the gas port.. 
• cut it flush with the barrel.. 
• turn the barrel over so it falls out.. and measure it.. this will be important later.. 
• put it back in with the gun right side up.. 
• slide on the gas block..
• turn the gun upside down again... 
• move the gas block around until the solder drops into the gas block which will lock it up.. 
• at this point you know the block is aligned... 
• pin or tighten it down.. however it is.. 
• now take a cleaning rod and GENTLY bend the solder that is in the barrel.. this will allow it to fall into the barrel... and fall out..
• once it is out measure it again and make sure you recovered all of the solder.. 

It sounds complicated but in practice it's not.. and it works 100%.. 

I’ve seen a similar method with a piece of uncooked spaghetti.

2 minutes ago, High Exposure said:

I’ve seen a similar method with a piece of uncooked spaghetti.

its just funny because messing around with it.. blowing air through it.. and all that.. I was SURE it was lined up... and it was at least partially lined up.. since air was getting through.. but once I had it fully lined up... problem solved... when you are dealing with holes that small.. being off even a little bit is going to add restriction.. and that restriction can be the difference between function no function.. 

 

I put a rifle lower and replaced the gas block and tube and it was a little better for a few rounds.I then swapped out my new PSA nickle Boron BCG with another known good BCG and it ran flawlessly!

Thanks for all the help guys...Much Appreciated!

 

I found the problem with the BCG and all my aggravation.  The gas key was cracked! See pic below.  Anyone else see this happen? The BCG was brand new from PSA and never worked out of the box!

 

 

I thought you said you tried a different BCG?

15 minutes ago, Shane45 said:

I thought you said you tried a different BCG?

I did but it was with the original gas block and tube. After replacing the block and tube, it still malfunctioned but not quite as badly. I was able to get off about 5 rounds then right back to the original problem. Then, with another BCG worked it flawlessly. I took a look at the bad BCG today and noticed a lot of black forward of the gas key.  I looked more closely and found that crack in the steel of the gas key.  In the beginning, I had 2 problems at once, making the solution harder to track down.

I'm just happy this stupid mystery is solved!  I never expected a crack like that on any gas key. Especially a brand new one!

This is a lesson.

Parts aren’t Parts - Everything is not created equal. 

Buy quality and cry once - there is no free lunch.

 

1 hour ago, High Exposure said:

This is a lesson.

Parts aren’t Parts - Everything is not created equal. 

Buy quality and cry once - there is no free lunch.

 

Lesson learned.....Thanks HE!

11 hours ago, JohnnyB said:

 

I found the problem with the BCG and all my aggravation.  The gas key was cracked! ...

Nailed it!

Glad to hear you finally solved the mystery.