As far as spring air pistols go, two come to mind which use a hinged trap door loading principle, of sorts. These are the Hungarian Lampagyar
http://www.vintageairgunsgallery.com/image/Mxru
http://www.vintageairgunsgallery.com/image/MpUG
http://www.vintageairgunsgallery.com/image/MK2S
and the Swedish Excellent 1950
http://www.vintageairgunsgallery.com/image/MnPB
http://www.vintageairgunsgallery.com/image/MkXA
http://www.vintageairgunsgallery.com/image/MXjQ
The Lampagyar is unusual in that the trap door is opened and closed automatically during cocking.