I honestly don't have a clue about this situation.

However, thinking on it, let's look at this from a strictly logistical standpoint. They filmed in Hawaii during a time when air travel was happening pretty frequently but not as much as it is today. Also, it's expensive to move things between the islands and the mainland - that part hasn't changed. It's quite possible they used the same props over and over again to save time and money on an already tight budget. Let's be honest, TV shows did not have budgets that films do. Networks want revenue for not a lot of effort.

I don't think it was so much to make a point, but rather to save a bunch of headaches of swapping weapons to and fro. While .38s were the weapon of choice (including the good guys) - we do see some 9mm guns show up from time to time.