https://bt-usa.com/products/tp9-n/

I asked HPD if the TP9 by B&T would be legal.
And his response was no because it was semi-auto and would fall under assault pistol.

I don’t understand.

Could someone explain why? My interpretation is that it would be fine.

   "Assault pistol" means a semiautomatic pistol that accepts a detachable magazine and has two or more of the following characteristics:

     (1)  An ammunition magazine that attaches to the pistol outside of the pistol grip;

     (2)  A threaded barrel capable of accepting a barrel extender, flash suppressor, forward hand grip, or silencer;

     (3)  A shroud that is attached to or partially or completely encircles the barrel and permits the shooter to hold the firearm with the second hand without being burned;

     (4)  A manufactured weight of fifty ounces or more when the pistol is unloaded;

     (5)  A centerfire pistol with an overall length of twelve inches or more; or

     (6)  It is a semiautomatic version of an automatic firearm;

but does not include a firearm with a barrel sixteen or more inches in length, an antique pistol as defined in this section, or a curio or relic as those terms are used in 18 United States Code section 921(a)(13) or 27 Code of Federal Regulations section 478.11.

HRS134-1

Maybe #'s 3 and 5?

4 might apply also. Looks like it’s 60 ounces. (3.75 pounds)

That’s a weird law.

  ...
     (3)  A shroud that is attached to or partially or completely encircles the barrel and permits the shooter to hold the firearm with the second hand without being burned;
...
     (5)  A centerfire pistol with an overall length of twelve inches or more; or
...

Maybe #'s 3 and 5?

#3:  There's no shroud.  There's a part of the frame that covers the barrel, no different than most semi-auto pistols.

#5:  The stated length is 11.9 inches.

I think the deal-breakers are #s 2 & 6.

The barrel has a 3-lug suppressor connector.  It's also a civilian version of a full-auto firearm marketed to Law Enforcement:

"The MP9 is the world’s lightest 9 x 19 mm select-fire weapon, ideal for surveillance teams, vehicle crews, CQB, SWAT teams and as a PDW, surpassing all other submachine guns in size, weight, and flexibility. This advanced, ambidextrous weapon is also available in semi-automatic only operation for the civilian market as the TP9."

#3:  There's no shroud.  There's a part of the frame that covers the barrel, no different than most semi-auto pistols.

#5:  The stated length is 11.9 inches.

I think the deal-breakers are #s 2 & 6.

The barrel has a 3-lug suppressor connector.  It's also a civilian version of a full-auto firearm marketed to Law Enforcement:

Not that I don’t want it legal but looks like a shroud as there appears to be no slide. It just shrouds the barrel and has a hand stop in front if I’m not mistaken.
#2 a factor.
I’ll guess #2, #3, #4.  6 maybe.

   "Assault pistol" means a semiautomatic pistol that accepts a detachable magazine and has two or more of the following characteristics:

     (1)  An ammunition magazine that attaches to the pistol outside of the pistol grip;

     (2)  A threaded barrel capable of accepting a barrel extender, flash suppressor, forward hand grip, or silencer;

     (3)  A shroud that is attached to or partially or completely encircles the barrel and permits the shooter to hold the firearm with the second hand without being burned;

     (4)  A manufactured weight of fifty ounces or more when the pistol is unloaded;

     (5)  A centerfire pistol with an overall length of twelve inches or more; or

     (6)  It is a semiautomatic version of an automatic firearm;

but does not include a firearm with a barrel sixteen or more inches in length, an antique pistol as defined in this section, or a curio or relic as those terms are used in 18 United States Code section 921(a)(13) or 27 Code of Federal Regulations section 478.11.

HRS134-1

Maybe #'s 3 and 5?

My guess would be 2-6. The forward grip built in the frame and the fact it mentions "submachine gun" in the description kinda works against you. Then the weight and length for technical specs. True most semi autos have a partial frame blocking the barrel or rather slide, but it reciprocated preventing you from holding it. I mean you could but would induce a malfanction. Just my guesses here.