Building a pump mag

I'm trying to piece together a pump mag.
I've searched an I found a youtube video, but It doesn't saying anything about the bolt bumper? It looked different.
Video:
https://www.youtube.com/watch?v=1p18G9IAwlw
I have a few wave springs, milled body, rail and a 3d-printed pump kit. Anything else?
thanks
MR

bumper needs to fit inside the wave spring. most people cut a stock bumper down.
you will also need a pump milled body and rail.

Some kits used an o-ring to keep the sprinkler centered.

Thanks guys! Sprinkler? are you talking about the wave spring? hmmm I wonder what size. And yes, I have a milled body and rail.

:rolf:
I design/engineer Fire Sprinkler Systems for a living. Guess I have sprinklers on the brain...:facepalm:
Yes I meant the wave spring.
:ninja: