[mete]

Can anyone tell me about Franz Langenhan rifles ?

[rufe-snow]

The only reference I could find was for a Friedrich Langenhan of Zella-Mehlis Germany. The time period was between the wars, ( early 20's to late 30's).
The Rifle was a .22 rimfire "dropping-block" target rifle. They were fairly expensive for that time frame ( Depression ), and built on a semi-custom basis. As long as you had the money you could have all the bells and whistles you wanted. They were commonly set up for off-hand Schutzen type target shooting. Some of the rifles were only marked "FL" or "FLZ", without Langenhan's name on them.