I believe it is a problem but would have to research the law again. The problem is the 1994 assault pistol law language that is on the book. That was one of the issues that was discussed among the 2A community back then.
There was a hometown member here posted his collection based on the legality of C&R and other items that are legal according to state law. You have to dig it up in the hive archive to get an idea how screwy Hawaiian firearm laws are.
On a side note, I am not sure if the Luger artillery model with the drum magazine is still on display at HPD HQ museum.