There are two types of flash hiders–the more common one is the type that’s effective at hiding the muzzle flash from the shooter’s view, while the other type is designed to reduce visible flash to bystanders. A suppressor can be mounted over either type of flash hider, but it will be most effective on a gun with a flash hider that’s designed to reduce visible flash to bystanders.
It is possible to mount a suppressor over a factory flash hider, but it is not recommended. The added weight of the suppressor can cause the barrel to bend or warp over time, which will negatively affect the accuracy of your weapon. Additionally, the increased heat from the suppressor can cause damage to the barrel and/or the flash hider. It is much better to use a dedicated threaded barrel and/or flash hider specifically designed for use with a suppressor.
There is no definitive answer as it depends on the suppressor and rifle in question. Generally, it is possible to mount a suppressor over a factory flash hider, but doing so may void the warranty on your firearm. Additionally, it may be more difficult to remove the suppressor if needed. Consult with a qualified firearm technician to see if mounting a suppressor over the factory flash hider is an option for your specific rifle and suppressor combination.