Heavy Barrel Help

Hi everyone! I'm currently in the middle of ordering parts for my first AR15 and I've hit a snag. In order to make my rifle compliant with my state's law (Maryland) it has to have a heavy barrel. I want to go with a 16" heavy barrel with a mid length gas system but I'm having a hard time finding any online. The only ones I've been able to find are ones with a carbine gas system. I was wondering if someone knew of where I could get a 16" HBAR with a mid length gas system that isn't too expensive.

Or should I just go with one with a carbine gas system and get an adjustable gas block?

Thank you!

Edit: For those curious I decided to go with a stainless steel fluted HBAR barrel with a carbine gas system from classicfirearms.com and an adjustable gas block