I agree. I recall reading that humidity much below 40% could cause cracking and permanent damage to the soundboard of my wife's baby grand piano. I can't imagine it is good to dehydrate gun wood and then take it out hunting in all kinds of weather. It would probably be best if your friend dropped the temp and raised the humidity gradually.

I have wondered if anyone makes a very small dehumidifier that would be suitable for 100-200 sq. ft.

A true sign of mental illness is any gun owner who would vote for an Anti-Gunner like Joe Biden.