It has a tubular magazine that holds 17 rounds.
This is the kind of problem common in just about everything that comes out of congress.
People who know little if anything about the subject matter try to pass 'feel-good laws' based on what they think will sound good to their supporters.
Up until the 1990’s the Marlin 60 would hold 18 rounds.
The magazine was reduced to 14 after that.
After the bolt hold open was added in 1985 it was necessary to close the bolt to get the 18th round in.
Tube magazines are part of the gun and not detachable, not covered by this proposal as far as I can tell.