Six different natures of Armstrong gun were introduced into the service, the 7-inch, 40, 20, 12, 9 and 6-pounders.
The first projectiles were of lead but these were then changed to iron coated with lead.
7 inch R.B.L. of 72 cwt. and 82 cwt.
The 82 cwt. gun was first issued in 1861 as a 100 pounder sea service gun. After February 1862 the weight of the shell was increased to 110 pounds and the gun was so designated the 110 pdr. After 1864 it was finally known as the 7 inch R.B.L.
Length 120 inches (face of muzzle to rear of gun excluding breech screw), greatest diameter 27.7 inches, 76 grooves each .06 in deep and .166 in wide, with a twist of one turn in 37 calibres, 883 of these guns were manufactured.
The gun at Fort Nelson is
Mounted on Platform, Traversing, Medium, No. 14 with Carriage, Garrison, Sliding, Medium no. 15 for 2ft. 7-in parapet.
Full charge 72 cwt - 10lbs RLG4
82 cwt - 11lbs
Shells - common bursting charge of 7lbs 10 ozs weight 98 lbs
- segment containing 112 x 3.25 segments
Bursting Charge 3 lbs 2 ozs weight 101 lbs
Shot - case containing 71.5 lbs of sand shot weight 69 lbs
The PAV with the 7-inch Rifled Breech Loading Gun in the West Haxo casemate at Fort Nelson
Diagram of the 7-inch RBL Gun (110pounder)