I have the rec7 perm. And it doesn't need to be changed to anything -.- I thought that when i first got it. I made it into a mac10 and.. then made it slower to a Ak103.. then made it into a AN-94. And overall having the original rec7 was better then the mod's i made it's recoil when your tap firing it is amazing. Taping rec7 it does like a burst effect you can spray it fully auto. Rec7 To Valk will make it slower and shitty dude.