The standard Jayco supplied gas bottle holders do not come with the ability to lock the gas bottle into them, some any shifty person with a shifter in their back pocket can have your bottle disconnected and be gone with it in under 30 seconds.

I was originally thinking to just get a couple of cheap bike locks and cables from K-Mart and go through the bottle carry handle and around the A-frame.
However....
The other day I was cutting some length of chain for another job around the house and had these link off cuts - what to do with them?
Step 1: Cut a large link/s of chain in half.
Step 2: Using a grinder, make sure the ends are flat and that the link stands vertical.
Step 3: Before any welding is done, check the link placement by putting the link and lock in place to make sure it all fits. I used some metal glue to stick the link in place to prototype and test. This also makes it very easy for the next step, as the link is already in place, so no need for clamps or magnets at the welding stage.

Step 4: Remove the gas bottle holders from the A-frame
Step 5: Weld, grind (if you need to tidy your welds up a little like I do) and paint/spray with a good cold gal.
Step 6: Reattach gas bottle holders to A-Frame
Step 7: Lock gas bottle in place :lock1:

Step 8: Admire your handy work while having a beer
Cheers,
Rohan

I was originally thinking to just get a couple of cheap bike locks and cables from K-Mart and go through the bottle carry handle and around the A-frame.
However....
The other day I was cutting some length of chain for another job around the house and had these link off cuts - what to do with them?
Step 1: Cut a large link/s of chain in half.
Step 2: Using a grinder, make sure the ends are flat and that the link stands vertical.
Step 3: Before any welding is done, check the link placement by putting the link and lock in place to make sure it all fits. I used some metal glue to stick the link in place to prototype and test. This also makes it very easy for the next step, as the link is already in place, so no need for clamps or magnets at the welding stage.

Step 4: Remove the gas bottle holders from the A-frame
Step 5: Weld, grind (if you need to tidy your welds up a little like I do) and paint/spray with a good cold gal.
Step 6: Reattach gas bottle holders to A-Frame
Step 7: Lock gas bottle in place :lock1:

Step 8: Admire your handy work while having a beer
Cheers,
Rohan