How hard do you plan on hitting it?
Well living in the HOT desert and having used them in the past I like many have had issues with expansion... the leaky nozzles... and leaks from the caps... so the tighter the better...
I was able to lessen the cap leaks with my long trusty 2 ft. screwdriver, little leverage on the ears... that helped with the expansion type of leaks, still a bit, but not as bad... I like the jiggler siphons so the nozzles aren't as much of an issue...
As to the hammer possible concern... I knew an old timer or two who mentioned that to be a concern... hence the reason I brought it up. Actually I haven't "NEEDED" mine in many years... might want to in the future when/IF ! I ever get the trailer set up...
I also have 3 5 Gal. aluminium water cans that I hope to rehab a bit...
Also does anyone remember if the leather cap gaskets were any better ??
Curt