I'm pretty sure that it isn't allowed but where is the reference that would forbid having a private shooting range on your own property?

I found the Revised Ordinances of Honolulu - Chapter 41, Section 6 which applies to "shooting galleries" or places that "are provided for the use of any person for a fee, pay or compensation of any kind to be paid, directly or indirectly, by such person." So this obviously shouldn't apply to a private target range.

Next, I found HRS 707-714, Reckless endangering in the second degree which contains the clause "provided that the provisions of this paragraph shall not apply to any person who discharges a firearm upon a target range for the purpose of the target shooting done in compliance with all laws and regulations applicable thereto." Therefore, it sounds like this wouldn't apply.

Does anyone know where this information is? 

Shooting on private property is completely legal in Hawaii.

There are 3 things, call them side effects of shooting on private property, that can get you in trouble though:
1.  Having a bullet leave your property.  Instant case of reckless endangering.
2.  Violating noise ordinances.  Earns you a pricey ticket.
3.  Displaying a firearm in view of the public.  Can get you charged with terroristic threatening.

So, the trick is to find private property that allows you privacy and noise abatement.  I regularly shoot inside my house, using powderless .22 rounds called "Super Colibri" by Aguila.  These, and other similar products, have less report than a spring-driven air gun.  I would shoot in my backward, but I can't absolutely guarantee that a neighbor won't see me and take offense.

Thanks for the info Tom.

It sounds like the main concern would be 2. Violating noise ordinances.

I tried searching for Honolulu noise ordinances and general Hawaii noise ordinances in the HRS but had a problem finding anything. The one thing I did find was from the Noise Reference Manual put out by the Deparment of Health.

Many people share in the common complaint of a noisy neighbor. It may be noisy children, pets or loud music.

If an open line of communication exists attempts can be made to resolve the problem. If there is a threat of a verbal or physical confrontation, notify HPD at 911. The HPD officer will make a "subjective" determination on wether the noise is unreasonable taking into consideration the circumstances surrounding the nuisance (i.e. the time of day or night, volume, etc.).

The appropriate Honolulu Police Department district station can also assist with finding a long term solution. The appropriate telephone numbers are listed on the back of this manual.

Another useful method is to contact mediation services such as the Mediation Center of the Pacific at 521-6767. Mediation is a process in which the parties to a dispute meet with a trained impartial person (a mediator) who helps them resolve their dispute. The mediator meets with all sides, together and separately, and uses a variety of techniques to help the parties come to a resolution.

That sounds like a great way to handle it.

And here is something I found from NoNoise.org.

(b) In all other districts, sound pressure levels from any activity shall not exceed, at any point at or beyond the lot boundaries, the maximum number of decibels for each of the octave bands as set forth in the table below provided, however, that where such districts permit residences or where such districts adjoin districts which permit residences, apartments or hotels, the maximum sound pressure levels at or beyond the lot boundary shall be reduced seven decibels from the levels indicated in said table for hours between eight a.m. and six p.m., and shall be reduced 10 decibels between six p.m. and eight a.m.

Octave Band Center Frequency (Hertz)	Sound Pressure Level (Decibels)
31.5	79
63	79
125	74
250	66
500	59
1,000	53
2,000	47
4,000	41
8,000	39

Where do you get your super colibris from? I've been looking for them but haven't seen them around locally.

Pretty sure I got them at Young Guns.  It's been a while, tho!

YG said they haven't had any come in for over a year.... =(

Call around.  One of these gun stores has some sitting on the shelf.  Also, come poke around at the gun show.  Some old timer may be cleaning out a closet and have 30 boxes to get rid of.

Picked up some CB Longs, in my CZ 452 with 25" barrel, it is twice as quiet as my RWS Diana 34 .22 air rifle!