1 Answer

It is not illegal in any of the states mentioned.

Washington State

Airsoft gun laws in Washington are fairly generic, meaning the state upholds the federal laws in regards to arisoft use. Airsoft gun laws in Washington state require all purchasers and users of arisoft guns to be at least 18 years of age. If you are under the age of 18 in Washington state you must be accompanied by a legal guardian or individual over the age of 21 years old to legally purchase an airsoft gun. This aisroft gun law applies to all airsoft guns in the state of Washington as well as all pellets (ammuniton) and airsoft supplies. In addition to the buying age, Washington state airsoft gun law requires that all airsoft guns must possess an orange tip, to prevent the appearance or confusion of a real firearm. In accordance with these 'appearance laws,' it is also illegal to brandish or show an airsoft gun in a public place in Washington state. It is only legal to play airsoft or fire the gun in designated areas; the toy weapons are not permitted in public areas such as parks, schools, etc. In general, the laws assocaited with airsoft in Wsshington state revolve around common sense use - See more at: http://gun.laws.com/state-gun-laws/washington-state-airsoft-gun-laws#sthash.zccd7Cck.dpuf 

Utah

Utah has no state laws governing Airsoft guns other than the federal law requiring the orange tip and the lack of any law requiring the tip to remain on the gun. However, the cities of North Ogden, Ogden, Centerville, South Jordan and South Ogden have laws prohibiting ownership of Airsoft guns. These laws have been uniformly enforced by law enforcement after an incident of mistaken identity by a police officer who faced an Airsoft gun without the orange tip and thought it was a real gun. Other cities throughout the country have laws ranging from New York City’s requirement that the entire gun be made of bright colored plastic, to the perverse law in some Illinois cities that prohibit the sale or transportation of Airsoft guns but allow the removal of the orange tips.

Read more: http://www.ehow.com/list_6733207_utah-laws-airsoft-guns.html#ixzz2x0I9syzl 

Montana 

Legal but with a list of rules depending on the style of air gun http://www.airsoftmontana.com/regulations.php 

Arizona 

In accordance with Arizona gun laws, the registration of firearms is not necessary. In addition, there is no requirement of permits or application for license to purchase, posses, or carry firearms. This includes air guns.  http://www.azleg.gov/FormatDocument.asp?inDoc=/ars/13/03108.htm&Title=13&DocType=ARS