Wait, the CZ 39 Hunter might be similar to the CZ Scout Rifle but in pistol form. The CZ 39 is chambered for .22 LR and uses a blowback operation. The trigger system is double-action only. Now, if there's an MP4 variant, maybe it's an upgraded version with better sights, a different trigger, or a different barrel.
Alternatively, "MP4" could be a typo. Maybe the user meant CZ 45 or another model. But since they specifically said Hunter 39 Mp4, I have to work with that. Another thought: in some contexts, MP stands for "machine pistol" or "multi-purpose," but the CZ 39 is a semi-auto pistol, not a submachine gun. Czech Hunter 39 Mp4
Another angle: the user might be referring to a modified version or a variant of the CZ 39 Hunter. Some manufacturers create different models by adding features. The MP4 could be a model with a 4th generation trigger system or safety features. Maybe MP stands for "Model Production" or something else. Wait, the CZ 39 Hunter might be similar