BudsGunShop.com - Compatability with 590 20 gauge

Yes it will fit but as others have said if you add it to the shockwave it becomes a short barreled shotgun Wich is an nfa item Wich requires a 200 dollar tax stamp and some lengthy paperwork. Hope this helps.

Yes, but it turns it into a class 3 weapon, which requires more in depth background check as well as 200 fee which is not refunded even if your app is denied. Good luck

while it will fit I would think hard about doing any modifications to a shockwave like james and edward stated it would become a short barreled shotgun which is a NFA device I would also not consider a brace at this time because of the current political situation with the ATF all it takes is a stroke of the pen and the brace is illegal it almost happened in 2020 Now with the current leaders who knows what may happen https://freerangeamerican.us/atf-pistol-braces-and-sbrs/

Yes, but if you put a stock on it, it is meant to be fired from the shoulder and becomes a short barreled shotgun.

John, yes Sir, it fits both the 20ga and 12ga no issue. The shoulder stock would change the Shockwave into a short barreled shotgun and needs NFA registration and a $200 Tax Stamp. A pistol grip brace kit would not : sb-tactical.com/product/590-sbl/ --- Cheers and stay safe!