Gas-checks in British RML heavy guns
Summary Table

Model
Rifling
Rifling
Stud/Gas-Check Combinations
Stud/Gas-Check Combinations
Stud/Gas-Check Combinations
Type
Grooves
Studded without Gas-Check
Studded with Attached Gas-Check
Studless with Automatic Gas-Check
-
17.72 inch
Polygroove
28
-
-
Y
16 inch
Polygroove
33
-
-
Y
12.5 inch
Woolwich
9
-
Y
Y
12 inch 35 ton
Woolwich
9
-
Y
Y
12 inch 25 ton
Woolwich
9
-
Y
Y
11 inch
Woolwich
9
-
Y
Y
10.4 inch 28 ton
Polygroove
21
-
-
Y
10 inch 18 ton Marks I & II
Woolwich
7
-
Y
Y
10 inch 12 ton Marks III & IV
Polygroove
32
-
-
Y
9 inch Marks I-V
Woolwich
6
-
Y
Y
9 inch Mark VI LS
Polygroove
27
-
-
Y
8 inch 9 ton gun
Woolwich
4
-
Y
Y
8 inch 70 cwt howitzer
Polygroove
24
-
-
Y
8 inch 46 cwt howitzer
Woolwich
4
-
Y
Y
7 inch 7 ton
Woolwich
3
Y
-
-
7 inch 6.5 ton
Woolwich
3
Y
-
-
7 inch 90 cwt
Woolwich
3
Y
-
-

Question: How many Woolwich rifle models are there and what are the ranges in size? 
Answer: There are 11 models of Woolwich rifled guns, ranging from 7 inches to 12.5 inches.