Found two "Hobby Lobby" references on the web. One's a "generic" arts & crafts place, and the other has RC model aircraft stuff....
Music wire would be a good choice, though!
I did another quick test. My collection of "Jumbo" paper clips are small enough to fit the hole. I thought that they wouldn't. Since I've got about 500 of those on my desk....
Also, I can't get the guide rod, spring, and plunger assembly out of my Compact Custom without compressing the spring with a pin. Unless there's some really magic trick to make me red-in-the-face....
The "Jumbo" paper clips are probably hard enough to not have to worry about the plunger cutting one off for you, and soft enough to cut with ordinary wire cutters (and not make dents in the plunger, too).
I think we have to say "depends on the gun" with respect to not using a pin to take these down.
Regards,