Legality of importin RS parts

[REMSoft]

Hi guys, gonna order some Mossberg parts to make my M500 stand out a little more. I'm getting a folding stock, heatshield and pistol grip pump for it from 'A certain auction site'. I was wondering how legal this is? As I understand it, it is fine unless I order a part that would contact the round in a firearm. Is this true?

[REMSoft]

Re: Legality of importin RS parts

Mods please close, this has been answered
"Correct, the law is only concerned with what the government call "load bearing" parts - essentially anything that is used in the real firearm to facilitate movement of rounds from the magazine and into the chamber, and then onto firing the round out of the gun itself (magazines aren't includes)

You'll be fine with a stock, heatshielf and pistol grip etc."