I missed your question on trigger guard bow dimensions. I don’t have anymore Oberndorf rifles proper, mostly rifles out of Thüringia so most are modified somehow from the original Oberndorf profile. I can dimension the one in this thread which is probably the closest: http://forums.nitroexpress.com/showflat.php?Cat=0&Number=340523&page=0&fpart=1&vc=1
It has been narrowed at the top of the bow however so maybe only some dimensions would be truly helpful.