After we got married I used the FRB "change of address form" to submit for a name change on my wife's LTC. I followed the normal procedure, mailing copies to issuing town, current town and FRB office. However, as you may notice the "Change of address" form is not well setup to indicate a name change. So, I sent a short letter basically just saying " My name has changed.....this is my old name....this is my new name.....please updated records as necessary". I think I also included a copy of the marriage certificate.
Funny thing....I think it took like 8 months or a year...something like that for them to update the system. After a while I stopped checking but it did finally show correctly. (TIP: you can use the "generate license validation" feature on the gun transaction website to what name is associated with a given LTC number)