I was nowhere near Oakley until 1969 when my school played football against Holy Name Primary. I can assure you that, inevitably, over the years i lost each of the attached missiles/projectiles from my Johnny Seven gun so it became a shooting noise gun only.
To answer your question, no it wasn't me. Sounds like it might have been someone from Abbey View or Valleyfield though if they were using a big, f**k off gun like that to rob Wee Jeannie's store. Mon the grannies