Apart from the unpredictable magazine catch that I've mentioned in another thread, I loved the way the 22 Compact shot at the range today. EXCEPT - the cap that protects the threads on the end of the barrel keeps wanting to unscrew itself. (The threads on my gun are all inside the slide, and the protective cap ends up flush with the front of the slide.)

The cap has two flats that accept a very thin open end wrench, which was NOT included in the box with the gun. So I would like to get a wrench to keep in my range bag. I've measured the dimensions and spacing of the flats on the nut but can't find anything in my usual tool sources to suit.

Where does one get the appropriate wrench for keeping this nut tight? And do you just use a weak Loctite to keep it in place once you crank it down? (I just finger-tightened it today, and it was loose again after just a few shots.)