Okay, let’s put this baby to rest
If you can bear to read more about this issue, check out the in-depth analysis at Castle Argghhh!. With pictures and everything.
His conclusion: 122mm HE. That had never occured to Murdoc.
UPDATE: I misread. He meant Paki 155mm. Sorry.

Actually, his conclusion was that it was a Pakistani 155mm HE round.
Come on ohwilleke, Ya gonna quibble over a measily 33 mm?