CHOKE-BORES. 



305 



time, such a requirement is not ohjectiouable ; but in 

 field work this cannot well be done, and due regard 

 should be paid to the fact in targeting. The exces- 

 sive strain at the muzzles of full chokes, occasioned by 

 the sudden resistance met with in the passage of the 

 charge at the constriction, necessitates, to ensure dura- 

 bility, the employment of extra thickness of barrels at 

 that point ; and for this reason, too, it is impossible to 

 obtain very close shooting from barrels which there 

 are thin and weak. This difficulty, however, in such 

 cases is sometimes ^?«r^m% obviated by slightly coun- 

 tersinking the muzzles and bushing them with rings 

 of iron or steel fastened with hard solder, and after- 

 ward boring these rings to the desired form. An- 

 other plan is simply to line the muzzles with hard sol- 

 der to the required thickness ; but it is a poor make- 

 shift at best, and does not work well for any length of 

 time. 



In the year 1868, a man named Roper invented a 

 close-shooting attachment for guns, which was simply 

 a sLort tapered cylinder of steel, the larger end of 

 which was fitted to screw on over the muzzle, the 

 smaller being somewhat less in internal diameter than 

 the barrel, and when attached the true choke formation 

 of bore was the result. These attachments were sold 



