AZ stabilizing brace

Dylan, yes it is legal. Just keep a copy of the Braces' ATF Compliance Letter with you and you will be fine Sir. Cheers and Happy Holidays!

while it should be legal I don't know of anyone who makes a brace to fit the Mossberg 590 action and I would be very cautious about making ANY modifications to the shockwave or the Remington version as they are such a grey area you could very well find yo