Brass caps to seal small 1 lb propane bottles -

[Sooner]

I found them at www.sportsmanguide.com.  F2P-217533.  They are a bit pricey  - $7.97 for a 2 pack.  They should make these handy bottles more safe to use and store.  They also sell the adapter to refill from a larger canister.
just saying
jim

[Oldrig]

Jim,
Thanks for the link. I just ordered a couple of those caps.
I don't need the filler gadget, at least not yet.
Grog to ya' for the info.

Best,

--Joe

[Sunset]

I did something really stupid with those 1 lb tanks. I used to store them in a unvented locker. Then one day I removed one from the grill and put it back in the locker. Didn't know it was leaking, when I opened the locker that evening to retrieve it it had leaked off filling the locker with propane. Proper storage is a must!! The caps would be a nice safety improvement.

[Godot]

I came to the conclusion years ago that the conventional wisdom of removing the propane bottles when they are not in use is completely backwards. In my experience the only time those  things leak is after removing them from a stove/lantern/heater. Leave them connected, and they rarely leak. I've also never experience a new, unused 1lb propane bottle leaking.

YMMV

[s/v Faith]

I had a couple of them in an extra battery box in the V-berth when I bought Faith.  I knew I did not want them there, but figured I would make a proper location for them later on.

Flash forward a couple of months, and I open the box.  It had water in the bottom that had apparently rusted the bottom of the bottles... they had both vented their contents to the bilge at some point.

Both of those mild steel bombs leaked without ever having had the plastic caps removed!