Re: Flash Hider/Crush Washer
If you have the 5C1 model, it will have a "bottom" like an A2 flash hider where there is no slot cut out. You will use the crush washer to make sure that part is correctly aligned. If you have the regular Phantom, use it anyway to make sure you have the proper torque setting. You just don't need to worry about indexing it.
On a side note, the only time you NEVER use a crush washer is if you are mounting the QD suppressor mount version. That one should be mounted with no washer or a peel washer only.