Hi Tracy and welcome back. Yes, it is on the Maryland Handgun Roster. Remember, you are limited to 10rd magazines. Cheers and stay safe! --- budsgunshop.com/product_info.php/products_id/1127/magpul+mag559-blk+ar-15+pmag+gen+m3+10rd+.223+rem+5.56+nato+black

Yes on the DD-300 AAC as it has the necessary Heavy Barrel, minus the 30 round magazine. Bud's will remove that.
Specifications
Mounting System M-LOK
Caliber 300 BLK
Muzzle Thread 5/8 × 24 TPI (Threads Per Inch)
Gas System Carbine
Barrel Length 16"
Barrel Profile S2W® (Daniel Defense's proprietary Heavy Barrel)
Product Weight 6.55 lbs
Length 32 1/4"-35 7/8"
Magazine Magpul PMAG 30 AR 300 B GEN M3
Case Daniel Defense Full-Latch Impact Plastic Case