Good advice, even the bit about boys town.
There must be a million simular stories about Mexico and firearms. One close to me:
A friend joined a group of other people from all over the US for a motorhome trip through Copper Canyon. I think there were ten-twelve motorhomes in the group. One of the owners had a single barrel 16 gauge shotgun in his motorhome, a couple of others had various ammo but no firearms.
About seventy-five miles into Mexico they were stopped and searched by Police. The guns and ammo were found. My friend had neither, but since he was a part of the group he was charged too. It ended up costing him over 25K to get out of Mexico with his motorhome and avoid jail. Some of the other folks were not as lucky. One individual had five .38s, for that they took the motorhome, fined him and he did almost two years in a Mexican jail.
You must also be very careful here in the USA while traveling with a handgun. If you do much traveling, I recommend you obtain a copy of "Traveler's Guide to the Firearm Laws of the Fifty States." You can get a copy by writing to:
Traveler's Guide
P.O Box 2156
Covington, Ky 41012
Or by calling (859) 647-5100, it will cost 12.95 including shipping and handling. THat's cheap when you consider some of the fines you may be avoiding.