Same here, been around shotguns for hunting and small .22lr all my life but now that I’m getting older I’ve been getting into the personal protection and target shooting as well. I would say go for the built upper for your first build, it makes it really easy to build your first rifle. Me and my girlfriend built our lowers and got our complete uppers and it went really well. I feel like building just the lower was a really good first experience for us and we are really happy with our builds.