72 THE GUN: AFIELD AND AFLOAT 



in loading, and this may adversely affect its action. 

 During recent years powder-manufacturers have suc- 

 ceeded in overcoming this disability to a great extent 

 by a general hardening of the grain of all compressible 

 powders. Several of the newer forms of nitro, the 

 concentrated, are so hard of grain as to be practically 

 incompressible. 



It is also essential, to insure good shooting, that 

 really good wadding should be employed, for inferior 

 wadding usually varies a good deal in density and 

 uniformity of texture as well as in thickness. With 

 wadding of this kind it is impossible to maintain an 

 even length in the loading of cartridges, the variation 

 in compressibility or in thickness of the wadding af- 

 fecting the pressure put upon it, so that a variable 

 amount of cartridge-tube is left for turning in. This 

 question of turnover or crimping of the case is of 

 vital importance, as any departure from the proper 

 standard is liable with several nitros to affect the 

 shooting to a considerable extent. The resistance 

 offered by an insufficient turnover does not suffice 

 for the development of a proper powder-energy. 

 On the other hand, an excessive turnover assists the 

 powder to develop its forces close to the breech of 

 the gun, and to an extent greater than is requisite 

 for the due propulsion of the shot. 



The amount of explosive force exhibited by a nitro- 

 compound is liable to considerable variation according 

 to the nature and amount of the resistance it encounters 

 at the moment of explosion. The resistance may be 

 increased from the- normal by, amongst other things, 

 the use of heavier charges of shot, or of similar charges 

 of a smaller size of shot, by very tight wadding, or, 



