Our Peck Crackers are from approximately 1969/1970.
The sizes were as follows:
Wired Sizes:
A4 6mm diameter chock, wire diameter 2.5 mm., Breaking strength 1,150 lb. Stainless Steel
A5 8mm diameter chock, wire diameter 3 mm., Breaking strength 1,750 lb. Stainless Steel
A7 11mm diameter chock, wire diameter 4 mm., Breaking strength 3,750 lb. Stainless Steel
A9 14mm diameter chock, wire diameter 4 mm., Breaking strength 3,750 lb. Stainless Steel
A12 19mm diameter chock, wire diameter 5 mm., Breaking strength 5,000 lb. Duraluminum
A16 25mm diameter chock, wire diameter 5 mm., Breaking strength 5,000 lb. Duraluminum
Slung Sizes:
B8 13mm diameter chock, cord diameter 5 mm., Breaking strength 1,500 lb. Duraluminum
B10 16mm diameter chock, cord diameter 7 mm., Breaking strength 2,250 lb. Duraluminum
B13 21mm diameter chock, cord diameter 9 mm., Breaking strength 3,500 lb. Duraluminum
B16 25mm diameter chock, cord diameter 9 mm., Breaking strength 3,500 lb. Duraluminum
Breaking strengths for the slung Crackers were calculated using hawser laid nylon rope, not newer kernmantle nylon cordage. Using the newer type of cord would result in a slightly stronger rating for each chock.