Well this is just weird .
I have many barrels threaded in 1/2x28 .
I have standard AR bird cage , TNA reverse fake suppressor and a S&J linear compensator .
They all fit my other barrels and the thread protector off the Derya fit the other barrels .
But the Derya barrel only the thread protector & the S&J linear will thread on easily.
If I try to thread on a AR birdcage or TNA reverse device they will bind up in 1/2 a revolution ?
I have a 1/2x28 tap and it runs through all the attachments easily .
I don't have a 1/2x28 die to run on the Derya barrel unfortunately .
????????????