I'll add to this since I just dealt with the issue of customs.
Ordered a Taipan, standard .177, from Air Gun Heaven, all because it has a CZ barrel (confirmed in an an email by Joost, the owner of AGH. Well, my Taipan spent 7 days sitting in Kentucky, until I spoke with Shayna at UPS....she first wanted firearms paperwork filled out....i gave her several links, describing the legality of airguns on the US and California.
She finally agreed to release the gun, but told me, "they need to check and make sure there is not a silencer attached or included"
Now I have have purchased several guns from Krale, one the HW110, with the screw on silencer, no problems. Also purchased 3 or 4 guns from Air Gun Heaven...never a problem....then I ran into this latest issue.
Ups really sux in my book, not only did they hold up my package for over a week, but now they can't find it between the hub in CA and the UPS store.
Not sure if things have changed or just new, untrained people in charge of customs, but there may be something happening with airgun importation...