THE ROYAL ARTILLERY INSTITUTION. 
247 
It might be supposed that reducing the calibre from O^T^to OffiO" 
would allow of a reduction in the weight of the barrel* but the present 
barrel of the Enfield rifle is well known to be too weak* especially near the 
muzzle; and if the calibre alone were reduced* leaving the thickness of the 
barrel the same as at present* it would make it still weaker. In order to 
retain equal strength*\eduction in calibre must be accompanied by increased 
thickness of metal. 
Grooves and Rifling . 
The form and number of grooves is a matter of minor importance if the 
twist of rifling is sufficient. Of all service large bore arms the Lancaster 
oval bore carbine with which the Eoyal Engineers are armed shoots the best, 
but it has no very marked superiority in accuracy above the naval pattern 
rifle which is rifled with five grooves* the width of the lands being a little more 
than half that of the grooves. The bullet leaves the Lancaster carbine twisting 
at the rate of 1 turn in 64 inches; the naval rifle at 1 turn in 48 inches; 
and the long Enfield* J 53 pattern* 1 turn in 72 inches. This latter twist is 
insufficient* the accuracy at long ranges being considerably inferior to that 
of the two shorter arms. 
The best twist for a 500 grain bullet in a calibre of 0*50" requires to be 
determined by experiment. The service small bore rifles with a calibre of 
0-451" have a rifle twist of 1 turn in 20 inches* which is probably more than 
is necessary* and it must be borne in mind that any superfluous rifling tends 
to heat and to foul the barrel. 
It is probable that a twist of 1 in 35 inches or perhaps even 1 in 40 inches 
might be found sufficient for the above-mentioned calibre and charge. 
Length of Barrel . 
The length of barrel of an infantry rifle depends principally upon the total 
length of musket and bayonet which is considered necessary. All European 
nations adopt about the same length* viz. 6 feet; it then remains to be decided 
how much of this length shall consist of stock and barrel* and how much of 
bayonet. This has been settled more by practical considerations as to the 
most convenient length of bayonet* and the consequence is that the present 
length of barrel of the Enfield rifle (39 inches) is considerably greater than 
is required for accurate shooting. 
The naval rifle and Lancaster carbines with barrels about 6 inches less 
than that of the long Enfield shoot very much better* owing doubtless to 
their steeper rifle twist. 
With proper rifling the longer barrel could be made to shoot as well* but 
the length is not necessary to produce the accuracy. 
[vol. v.] 
33 
