Joe reminds us of a poor way in which the law was drafted, that exempts having a gun within 1000 feet of a school if you have a license from the state the school is in, but doesn’t in other circumstances. It is therefore possible to be charged with violating the federal gun free schools act if you carry on a reciprocal out of state permit.
The Gun Free School Zones Act was held unconstitutional once, but Congress rewrote it. It’s likely it wouldn’t stand up again if challenged. But it is worth noting.