If you own a Glock pistol in California, you are subject to certain regulations regarding modifications to your firearm. It is important to ensure that any modifications you make do not violate California gun laws or result in the firearm being classified as an illegal assault weapon. The California Roster of Certified Handguns lists the models of handguns that are legal to purchase in the state. To be included on this list, a handgun must pass a thorough testing process to ensure it is safe and reliable. Some modifications, such as adding a magazine with a capacity over 10 rounds or a threaded barrel capable of accepting a flash suppressor, may disqualify the handgun from being listed. Ghost, Inc. offers a range of Glock parts and accessories that are legal to use in California, including firing springs and trigger connectors. However, it is important to verify that any modifications you make do not violate the law.