It's leaking gas. Check around the gas block & look for carbon blow by around the barrel, around the gas tube & gas block. Gas can leak around the gas key on the carrier, as well as the end of the gas tube & gas key.
You can use Green Lok Tite to seal around the gas port and gas block. Apply a thin bead of Lok Tite around the gas port, re-install the gas block. Allow the Lok Tite about 23hrs 59 minutes to set before shooting.
Other things to look for:
Look to see if there is a distinctive "knob" on the end of the gas tube.
If any of those points do not correct your issue, pull back on the charge handle slowly & feel for any binding.
I did encounter an issue one time where the buffer tube was screwed in too deep and the buffer was not traveling far enough when the bolt cycles. The buffer tube should only be screwed in far enough to cover the shoulder of the buffer dtent.
This is what is should look like:
Buffer tubes with a notch in them, when screwed in too far can cause the buffer to bottom out too quickly in the cycle & bounce putting too much forward momentum into the carrier.