I purchased a PWS 7.5" upper in .223 Wylde from the local gun store, and finally grabbed a lower to put the whole thing together. I slapped it on, took it to the range and it is a single shot pistol now. For some reason it does not cycle at all. After I cycle it by hand (with a significant amount of resistance) it still only single shots. I pull out the mag and nothing changes, I tried three different lowers, and still nothing. Single shot only. Somebody help me here, I really don't want to pay a gunsmith to take a look at it and tell me it's an easy fix but charge me an arm and a leg. I was shooting Federal 5.56, which I was told could be fed through the .223 Wylde chamber.

Do you have it on the correct gas setting for  the ammo you're using?

Or maybe a buffer weight issue?

I was going to say the same thing check your gas setting also we need to know more is your bolt going partially back or not at all

Certainly sounds like you are on the wrong gas setting,,

The BCG does not move at all... Doesn't even open the dust cover back up if you close it. I tried all 4 piston settings, nothing changed.

Have you contacted PWS?  They may have an easy answer.

Is the piston head properly attached?  I had mine come off while inserting the bcg because I didn't align it properly.  Maybe that could cause your issue?

I had a friend who had a less severe problem than yours (ejection of the brass was very "weak" even with the gas setting at fully opened), and he called PWS. They ended up replacing the bolt carrier group.  I would talk to PWS since gas setting if the gas setting does not correct the problem. Unless they are back up, their customer service is great.

Check to make sure you have the 2nd part of your piston--I just got one and they forgot to put one in, or after testing it got cleaned and not put back in.  They mailed me a new one.