There's nothing wrong with saying clip in this context. The only reason to object is if you're being annoying and pedantic and you've forgotten that there can be more than one term for the same thing.

Nobody is confused by saying "clip", nobody thinks you're charging a glock mag with a clip from the open ejection port. There's like one gun in history that uses both clips and detachable magazines, so if we're talking about that specific gun and the difference is operative to the point, then you can complain.

This is similar to people insisting on "firearm" over "gun", or "suppressor" over "silencer", or "round" over "bullet". Some of them might be more technically rigorous terms but unless you're discussing the finer points of gunsmithing or ballistics you usually don't need to care.

Also, remember the golden rule of pedantry: if you understood well enough to correct them, you don't have to correct them.