The end plug on my 77 is flush with the comp tube wall .

I would take the cocking link off and with everything spotless clean measure and check comp tube fit to barrel,
then offer cocking link to it to see line up of cocking link to pivot hole and if out of line bend the tang bit to suit .

I think it is this that is bent as the straight bit is far stronger , and that is the weakest bit .

I have repaired 77's with this problem before having to weld some at the bend as they had cracked !