I knew I was moving back to Oahu for good after my time in the military, so I took all my handgun mags that held more than 10 rounds and installed "mag blocks" to limit them all to 10 rounds. My Sig P226, Hi Power, Glock 19 all hold 10 rounds now. If you go to
http://www.magazineblocks.com/magento/ find the product you need, install with the permanent epoxy you will be good to go. I kept my rifle magazines (Hi Cap) AKs, ARs, FAL, M1A mags and only put 5 in them when I go shooting at Koko Head. Good source of knowledge from forum members on this site guided me with the legal rules of what I could bring back and not bring back. One regret, I had to sell my Ruger Charger and S&W M&P 15-22P Pistol since they were considered Assault Pistols and banned in the state.
Also, don't bring any magazines when you go register, be sure weapons are unloaded and transported in gun cases.