Keywords: 9.2inchHowitzerMkIBreechMechanismDiagram.jpg Breech mechanism of 9 2 inch Howitzer Mk I US service Handbook of artillery including mobile anti-aircraft and trench matériel 1920 page 289 <br>http //www archive org/details/handbookofartill00unitrich 1920-05 United States Army Ordnance Dept PD-USGov BL 9 2 inch Howitzer 1 Welin breech block BL 09 2 inch howitzer Mk I |