If you are wondering if this is MD legal, it is not, per the SA web site.
Stay safe & have a great day!

It does have a Heavy barrel, as far as if that is stamped on the barrel, I'd contact Springfield Armory.

This is Springfield Armory take on the M16A2. The barrel is 20" chrome lined 1:7 twist chrome moly barrel. Contact Springfield Armory for barrel markings. Full specs can be seen here:
springfield-armory.com/ar-series/sa-16-rifles/sa-16-a2-556-rifle/
https://support.springfield-armory.com/contact-us

Hi and welcome. This model has a 20-inch heavy-profile barrel with a 1:8" twist offers superior accuracy and stability—ideal for target shooting, long-range training, or hunting applications. Its threaded muzzle (1/2x28) is ready for a compensator or suppressor. Cheers, stay safe and enjoy! I would contact Springfield Armory Customer Service on the specific barrel stamping at -- https://support.springfield-armory.com/contact-us