Box full of newspaper will still stop it.
Let me know if you need newspaper. Can back it with plywood if need.
.34 gr. Slug. .22LR is pushing pushing 40 gr at 1150 FPS.
Shot a .22LR into a box of newspaper and a plywood backing just in case. Box of newspaper stopped it.

Can you make a homemade suppressor for an air gun legally ?
Didn’t see anything in the H.R.S. Prohibiting it.
Commercial air guns come with built in suppressors.
The .22 caliber break barrel I had with built in suppressor barrel was quieter than my Benjamin pump.

I am not a lawyer.

They all pretty much already have moderators/lcd's on them. But they move a lot of air even at sub sonic velocities.

Got it.
Noise problem is gonna be a noise problem.
Check out YouTube though. Some creative suppressor ideas for air guns.
If it’s legal.

Not oahu, BI, but I shoot rifle and pistol in my back yard for practice all the time.   One old crone neighbor apparently called the cops who told her it was quite legal if kept on my property.

Ah, the joys of living on the BI. I have a 25 yard handgun range set up in my backyard and nobody ever complained about me shooting as I hear my neighbors shooting too.

I do have a yard with a lot of chickens, that tear up my yard and crap everywhere.  Both my neighbors to the left and right of me feed them. The wife can't stand them. I have a couple of airguns I can use, but the ones I really want to shoot are not backyard friendly. If I remember correctly I wouldn't be able to air up near the benches? I would have to go down to the parking lot. Put it this way, the last time I went to Kokohead, you could shoot at the gong deep in the valley and set up 200 yd targets.

It is unlawful to feed feral chickens/cats or shoot them for no reason (animal cruelty again)..

    Had a similar issue with a neighbor (tenant) feeding the chickens in her yard and then the whole flock would come over to my place crap and tear up the garden/ plants.
I started picking them off  with airgun in my yard and she called the cops.

cop.. You shooting chickens with pellet gun ?
me.. Yup
cop... you can't shoot air gun in yard
me... Explain rules about projectile not leaving property.
cop...shooting chickens is animal cruelty.
me ...I'm not being cruel, I am hunting them to feed my dog.
cop... Got  a hunting license ?
me... no need hunting license for chickens, no such thing.

   I then inform him that feeding feral chickens is illegal.
first offense was $50, second $100 forgot what the third offense cost.
(This was back in the days when the Boy scouts were doing "Chicken Round ups" for $5 per head. 2004ish ?).

  Cop went over and wrote her a $50 ticket, end of problem. 

Can't find that law (not really looking) but it looks like they tried to increase the fines.
https://www.civilbeat.org/beat/feeding-feral-chickens-could-result-in-500-penalty/

Unreal.
Can shoot feral peacocks but not chickens.
Go figure.
Hunting license $10.

https://dlnr.hawaii.gov/recreation/hunting/bird/

Unreal.
Can shoot feral peacocks but not chickens.
Go figure.
Hunting license $10.

https://dlnr.hawaii.gov/recreation/hunting/bird/

$20, $10 for bird sticker. Total $30

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