RR;
if bearing is the first identifyable data (i.e. you're looking through the periscope to see the target in the first place ergo the bearing is obviously displayed by your scope) why would that be the last piece of info to input? If I understand your point correctly it's because of the PK 'memory' issue but isn't that only a problem if you don't 'reset' the PK?
If the PK isn't 'reset' then yes, the last firing solution is still valid and your torps go off in a relatively bizarre direction (guess how I found that out?LOL

).
I thought I had this firing stuff figured out (I still miss as much as I hit, LOL) but now I'm confused again (not hard to do at the best of times).