TexasCHLforum.com

I have two of those boxes - a smaller size in the trunk of my sportscar, a larger one under the seat of my pickup. I keep a 9mm non-carry weapon in each one, with 2 extra magazines.

Cabela's has both sizes for $29.95.

I recommend you buy only the larger size. I can stow my carry P3AT plus the existing pistol in the larger size, but not the smaller, by taking out the spare mags.
The exception might be when you use them for checked baggage at the airport, where smaller is better.

If I had it to do all over, I'd order 4 from COM just to get them keyed alike. As it is, I keep the proper key on the same ring as the key for the car it's cabled to.

I looked at the ammo can locks. Very ingenious, but all it takes to defeat them is wire cutters, or perhaps even a pair of pliers. If I had a junk ammo box, I'd see how tough that wire is.