THE LOCK. THE STOCK. 227 



there is a patent breech, or revolving cylinder or chamber, 

 the former mark is also to be impressed on that. 



On all barrels the gauge size shall be struck both at the 

 provisional and definitive proofs. 



The provisional proof charge for a No. 12 double barrel 

 shot gun is 350 grains of lead, and 12f drs. of powder; and 

 for the definitive proof, 219 grains of lead and 8 drs. of 

 powder, the charge of each being increased or diminished in 

 proportion to the gauge. Now, the above weight of powder 

 being nearly three times the usual charge, it may be con- 

 sidered that if a gun, when finished, passes this severe ordeal, 

 it is scarcely likely that it will burst with ordinary care 

 when employed for sporting purposes. The proof charges 

 are now the same in London and Birmingham. 



THE LOCK. 



The Locks of guns vary a good deal, but the principle in 

 all cases now is to cause ignition by a blow on some deto- 

 nating substance. This is effected by a spring, which is 

 compressed and held back by some means, and when let go by 

 the pressure of the trigger it drives the striker on to the deto- 

 nating powder. The various plans adopted will be alluded 

 to under the respective guns ; but it may be mentioned that 

 the form of the mainspring is the chief part in which they 

 differ. In the ordinary lock the spring consists of a 

 plate of steel bent to a very acute angle, one arm being 

 fixed to the lock plate, while the other is moveable, and at 

 its free end acts upon the striker. The second form consists of 

 a spiral spring which, when compressed and let loose, drives 

 a striker, having a needle attached, straight forward to the 

 detonating powder. 



THE STOCK, INCLUDING THE FALSE BREECH. 



The object oftfo stock being to enable the shooter to adapt 

 the gun to his eye, and having little or nothing to do with 

 the mechanism or performance of the piece, it is of im- 

 portance that he should be exactly suited in the former respect. 

 If a gun stock is not of proper length, and bent to fit the 



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