RECOIL GEARING FOR PUNT-GUNS 185 



and two wrought iron straps " shrunk " around the barrel and 

 holding ends of the loop. This may be noted by reference to 

 our sketch. The iron straps are made small for their seats. 

 By heating them to a bright blood-red they are expanded, and 

 can be driven on. They are then cooled, and thus by contrac- 

 tion secure a very tight grip on the barrel. 



We may add, for those who intend using a spring recoil 

 gear, that our sketch is made from one which has proved of 

 good service in years past, and is of safe dimensions and of 

 original expert design. The width of the sliding block which 

 lies in the double eye pivot is that of its vertical diameter. 

 It is best to make this gear, except the springs, of wrought 

 steel, but it may be made of similar metal as the barrel, 

 and if this latter is not steel, some extra allowance made 

 in thickness for proportionate strength. The back check 

 spring should be lighter (i.e. of thinner wire) than the recoil 

 spring, as shown. The guide inside the coils of the back 

 check spring should nearly fill or fit. This guide, if too small 

 in diameter, will allow the spring to "side bulge." 



The whole gear can be readily dismantled, which may be 

 easily seen on reference to sketch. If by some unforeseen 

 cause a spring should happen to break, an iron washer or ring 

 of same size as the coils, placed between the broken parts, will 

 set matters right until such time as a new spring can be 

 procured and fitted. In fitting the springs the requisite 

 amount of contraction is an important item. The correct 

 length of the springs is also of importance, for, unless this, 

 as well as the proper amount of contraction, is allowed for, 

 the correct balance of the gun will be affected. These points 

 are not of so great importance in the case of fitting a complete 

 gear of this kind to an old gun, for then the point of balance 

 can be ascertained experimentally, as when the loop is made 

 with the gun, or new springs are being fitted which may be 

 slightly longer, shorter, weaker, or stronger, for it is difficult 



