4 
the latter’s axis; such motion being, however, limited by the annular shoulder 
formed on the anterior extremity of the ring. 
When the projectile is rammed home, the outer surface of the ring B is forced 
against the cone of the rifling at the point in which the grooves originate and is 
compelled to slide on the conical and serrated surface of the driving-band A. 
This movement expands the diameter of the ring B which is jammed against the 
sides of the bore and invariably remains attached to the driving-band. The ring is 
prevented from sliding further backwards by its shoulder and cannot revolve on 
account of the serrations on the driving-band. In addition to the obtained increased 
diameter of the ring B, this sliding motion has also the effect of projecting the 
rear part of the ring over the first cannelure of the driving-band A thus forming 
a cup, the rim of which is forced forwards on discharge and prevents the gas from 
escaping. 
The advantages claimed for this new system are:— 
1. —Guaranteed obturation leading to greater shooting accuracy and uniformity 
of results. 
2. —Its action is automatic and independent of the correct centering of the 
projectile in the chamber. 
3. —Simplicity and economy of construction as the ring B can be punched 
out. 
4. —No further precautions for transport are necessary than those at present 
used. 
5. —Preservation from erosion and hence prolongation of the gun’s life. 
