The Mark II differs from the Mark I in being fitted with the service ·303-in. barrel and muzzle attachment for ball firing, whereas the Mark I has a special muzzle attachment and a heavy barrel. The difference in the barrels affects also certain other parts. In both Marks I and II converted guns the attachment for ball firing must always be on the guns, as, owing to the greater weight of the component parts, these guns will not work without it. The tangent sight is graduated to 2,500 yards. The weight is 64 lbs. In other respects they resemble the ·303-in. gun except that the connecting rod is not above the horizontal and that there is a space of about ⅒ of an inch between the projecting arm of the crank handle and the resistance piece. Ammunition. All marks of ·303-in. ball ammunition may be used, but care should be taken to select ammunition of the most recent manufacture. Mark VII can, however, be used only in guns specially modified to take it. Explanation of Plates I and II. 1. End of crank. 2. Projecting arm of crank handle. 3. Crank handle. 4. Breech casing. 5. Fusee spring } } 6. Chain } Dotted } lines in 7. Fusee } Fig. 1. } 8. Spring box } 9. Resistance piece. 10. Buffer spring. 11. Check lever. 12. Lock casing. 13. Firing lever. 14. Trigger bar. 15. Projection on trigger bar. 16. Trigger. 17. Tumbler. 18. Lockspring. 19. Firing pin. 20. Crank. 21. Crank pin. 22. Connecting rod. 22A. Cotter. 23. Side levers. 24. Sear. 25. Extractor. 26. Barrel. 27. Ejector tube. 28. Horns of extractor. 29. Keeper bracket. 30. Side cams. 31. Cover spring. 32. Cover. 33. Gib. 34. Adjusting screw for fusee spring. 35. Extractor spring. 36. Handles. 37. Double button. 38. Trigger bar spring. 39. Gib spring. 41. Extractor levers. 42. Belt. 43. Upper extractor stop. 44. Groove for side plate spring. 45. Cartridge grooves. 46. Ejector tube spring. 47. Side plates. 48. Guides in which flanges of lock move. 49. Guide ribs for extractor. 50. Cover lock. 51. Gunmetal block. 52. Hole for firing pin. 53. Safety catch. 54. Screwed head. 55. Connecting rod spring. 56. Crank bearings. 57. Slots, breech casing. 58. Crank stops. 59. Ammunition belt box, No. 2. 60. Feed block. 61. Top lever feed block. 62. Cork plug. 63. Feed block slide. 64. Top pawl. 65. Bottom pawl. 66. Band roller. 67. Barrel casing. 68. Screwed plug for filling. 69. Asbestos packing. 70. Packing gland. 71. Cannelure for asbestos packing. 72. Gunmetal valve.