heres some of the things I learned from my grand adventure into trying to aquire a suomi:
Centerfire systems [ the biggest distributers of TNW's suomi] will absolutely not ship these in anyway shape or form, with or without magazine, anywhere in MD. There is no just reason for it, they are just too afraid. It has led me to stop conducting business with them.
Centerfire sells on gunbroker under a different name and still won't ship a magazineless suomi to md.
everyone else on gunbroker sells the suomi at a higher price, but many will ship to MD, look for gun owner friendly sellers who are not afraid of scary MD gun laws. expect to pay around 500 before shipping on one, it's what I had to do.
Suomis are cash and carry as they aren't on the regulated list, find a md FFL who isn't afraid of scary MD gun laws [ winks sporting goods in princess anne actually said that "just because it's not on the regulated list, doesn't mean it's not regulated"
TNW kits are better now than before, but still require milling and welding, just a minimal amount, this may be the way for you.
disassembling the gun for cleaning changes the headspace as the screw on end cap is actually the head space adjuster, screw it back on too tight and the gun no workee [ ask me how I know]
that being said, the gun is an absolute tack driver at 50 yards and is an amazing amount of fun. good luck, hope you get one.