Help! My AR pistol has turned into a single shot

Will not pick up next round on mag. Tried different ammo, cleaned, different mags and no help. Gas block does not appear to be adjustable. Is there a AR pistol guru on THF that I can send this bad boy to?

Undergassed, is my bet.

In my limited AR experience, I've decided I will not own an AR without an adjustable gas block.

I installed a Syrac adjustable gas block on my LR-308 that was ejecting at 1 o'clock (over-gassed). Easy to instal and it solved the problem.

Either your gas block has shifted, or your gas port/tube is clogged.

Yup...I can imagine a really, REALLY gunked up bolt doing that too. Maybe.

Correct that it sounds like the gun is undergassed. However, an adjustable gas block will not help at all if indeed the gun is undergassed. Adjustable gas blocks simply allow the user to restrict gas flow (like you experienced with your LR-308), but they don't give you any extra gas flow over a standard gas block. The size of the gas port in the barrel determines that.

OP - It is likely that your gas block has shifted, or you have gas leaking from the gas tube (usually occurs where tube fits into block). Take the gas tube and block off the gun and look at the ring of carbon buildup around the gas port on the barrel. Gas port should be perfectly centered in the carbon ring, i.e. there should be an even amount of buildup all around the port. If it's not, that will tell you that your gas block shifted. Simply reinstall the block in the proper location and you should be good. If the gas port is centered in the carbon when you look, blow compressed air through the gas tube. You should be able to feel if air is escaping anywhere. That will tell you if you need to replace your gas tube.

People like to talk about gas tubes clogging, but it doesn't really happen. Anything is possible, but with the amount of pressure flowing through that tube when you shoot, it's highly improbable that a clog would ever be able to form.

My cardiologist disagrees when I provide this very same explanation to him....

Didn't say it was likely.

But of course!

Learn something new every day.

Aluminum gas blocks will erode and cause gas to leak out from the sides.

Blockage or leak causing a gas shortage like described above and good way to check for it above.

That or you let FiremanJG handle your AR as there is a History

Very helpful. Thanks guys

Check the gas rings on the bolt. If the slits have somehow managed to align themselves it will cause undergassing.

This is a myth. No need to worry about alignment of gas rings on an AR-15.

Now, if they are worn out they should be replaced, but alignment of gas rings causing gas issues is a myth that has been proven false time and time again.

I'm just going to stick with what the Marine Corps taught me. Honestly, I really don't see how it could cause the issue since they're outside the gas tube port on the bolt.

Yup