That out of the box thinking will land you in a box cell.

The easiest, legal way to do this for your step dad and you to go to an FFL and he can give you the gun but you need to do the transfer paperwork/dros and the 10 day waiting period (plus whatever the paperwork fees are).

Having said that, Your mom MAY be able to gift it to you via the family route bc your mom and step dad are both owners of said firearm. I’m not 100 percent on that though, so you’re gonna wanna double check that.

I feel you though; both of my parents remarried and its shitty that in the eyes of the law, my step parents and especially my step grandmother arent considered “real family” bc they arent blood related to me. My step grandmother treats me no different than her other grandkids and loves to just sit and talk with me. She’s been my grandma for two and a half decades as far as I’m concerned. The state doesn’t know shit.