It's legal under federal law to sell a long gun to a resident of another state as long as the weapon is legal in both states, and as long as the sale is----i.e., if TX required a permit to purchase, which LA does not, then the sale would be illegal. That said, many FFLs act stricter than the laws out of ignorance or fear of liability. Heck, around a decade ago I had the staff of the Cabelas in Gonzales insist on doing a 4473 and NICS check on me for a black powder revolver. As this was before Cabelas stopped selling them online, I took the risk of putting my CC info over the air to just order the thing on my phone to be shipped to my house, just to try to make a point to the idiots.