Blackpowder

120 grains = .812"
150 grains = .814"
160 grains = .814"

777

150 grains = .816"*

SR4756

36 grains = .812"
38 grains = .812"
39 grains = .812"

Longshot

31 grains = .811"
35 grains = .814"

All in cheddite hull with a base of .806"

For comparison Remington 00 Express buck has the same base of .806 and expands to .816"*

* largest measurement directly at base. All others further up the brass