No one has said they are the same.
I have a ULE, Tac One, and XMT Classic RT body, Ion threaded feednecks that I own screw on with zero resistance.
Oh, you dod not say you had a benchmark frame. They allow a huge variable of effects that cause mags to not act right.
Ion threads are not the same as Angel threads, likewise Ion threads are not the same as ICD threads. Now you might get lucky and the one you have threads