Issue with new upper?

[esizer]

I ended up getting one of Palmetto's rifle kits that had a nitride middy 16" upper. I slapped the upper on a PSA lower that I found on sale and kept the LPK for another build/day.

I put a NiB BCG in there and it was passing all the function checks. I got it out to the range yesterday and put a full 30 round PMAG in with the BCG locked back. I sent it home with the bolt catch. I went to fire and the hammer dropped...but the round didn't go off.
It was a little difficult to extract but I eventually got it. The next round chambered, fired, etc. just fine. A few times I had the same scenario where it seemed like the BCG wasn't fully going into battery. Sometimes I was able to get it the rest of the way there with the forward assist, other times I would just have to extract the round. Sometimes extraction was tough too.

It seemed to be most prevalent on the first round of a new magazine. When I got it home, I cleaned it up a bit and cycled some non live test rounds. Same issue...when I drop the bolt catch, the BCG doesn't always make it all the way into battery. Manually cycling the action resulted in it happening quite frequently.

I swapped out the NiB BCG for the one that came in the upper and it seemed to be a little better but still wasn't 100%.

I thought it might be too much tension on the extractor and it was having troubles getting over the rim...but with two BCGs having the same issue, it seems less likely.

Maybe the chamber is tight? The only other thing I can think of is that the action spring is weak because it seemed to have the most issues with a fully loaded magazine.

[KS63]

Try different mags? What ammo are you using?

[OneGuy67]

Should loosen up with a few more rounds through it.

[colorider]

Maybe funk in the chamber. Scrub it with a chamber brush

[Colorado Osprey]

After removing one of the bolts from the carrier insert it into the barrel extension. Twist to lock it down. It should insert and lock down and unlock easily by hand. Sometimes barrel extensions will have burrs or slight dimensional changes that don't allow your bolt to mate easily with the barrel extension. These are usually worked out with a little oil and sending a bunch of rounds through the gun. Another reason to match a BCG to an upper and not swap between guns. If you find this to be the case contact the upper manufacturer and they may swap out your upper for a different one.

[esizer]

Thanks all! I have an email into PSA to see what they recommend as well. If they don’t want me to send it back for repair...I’ll clean the chamber, see if I have any issues with the bolt locking up in the barrel extension, and then try some different magazines/ammo.

[SideShow Bob]

Try running it with your magazines down loaded to 28 for a bit to see if the problem continues.
While you are cleaning the chamber clean and look closely around the locking lugs of the barrel extension for burrs or metal filings.

[esizer]

Palmetto told me just to send it back in and they'll take a look.

[Joe_K]

https://youtu.be/JnWqNSD9eEs

https://youtu.be/FhhQ9sEac6o

A lot of the AR 15's being offered by companies like PSA are leaving the factory with any combination of the following issues:

- No headspace checks.
- Rifle upper combined with M4 feed ramp cut barrel extensions.
- Undersized chamber.
- Roughly cut chamber and or barrel extension.
- Massive gas port dimensions.
- Under buffered, (using a standard CAR15 instead of an H-2 or H- 3)
- Improperly staked Gas key.
- Unstaked castle nut.

Also pretty much any Armorer or Gunsmith worth their salt will tell you to stay far and wide from NiB coated anything that needs to have precise metal to metal contact. NP3 might be a better alternative, but there is a good reason the .mil doesn't use Nib in their Bolts or Bolt Carriers.

Good luck, hopefully PSA fixes the issue for you, but don't be suprised if you have to take your replacement AR in to a competent local smith and have them fix it.

Sent from my SM-G920T using Tapatalk

[esizer]

https://youtu.be/JnWqNSD9eEs

https://youtu.be/FhhQ9sEac6o

A lot of the AR 15's being offered by companies like PSA are leaving the factory with any combination of the following issues:

- No headspace checks.
- Rifle upper combined with M4 feed ramp cut barrel extensions.
- Undersized chamber.
- Roughly cut chamber and or barrel extension.
- Massive gas port dimensions.
- Under buffered, (using a standard CAR15 instead of an H-2 or H- 3)
- Improperly staked Gas key.
- Unstaked castle nut.

Also pretty much any Armorer or Gunsmith worth their salt will tell you to stay far and wide from NiB coated anything that needs to have precise metal to metal contact. NP3 might be a better alternative, but there is a good reason the .mil doesn't use Nib in their Bolts or Bolt Carriers.

Good luck, hopefully PSA fixes the issue for you, but don't be suprised if you have to take your replacement AR in to a competent local smith and have them fix it.

Sent from my SM-G920T using Tapatalk

That's certainly the first I've heard of NiB not being a good idea for bolt carrier groups. What is the issue?
I've seen a few barrel extensions with a NiB finish too. Is that another area where it's not a good idea? Just curious what your thoughts are.