Pump mag project needs a little help

[sbpyro]

I picked up a pump kit for the mag from the attic.
Lucky for me I had an old mag with the rail with a slot milled for the cocking rod. The classic body had the slot for the rod also. I had a cocking rod made and it matches the dimensions on the drawing perfectly. Changed the blue bumper to the black one. added spring to back of the bolt on top of the bumper etc. Installed pump kit as directed.
The gun would not cock back with the spring installed.
SO I removed it and tried it and it worked twice before it would go back to semi mode. Anyone with any ideas on what went wrong? Thanks ahead of time.

[Strider]

Is the black bumper a pump bumper or a bumper that looks the same as your blue bumper?

The pump bumper should sit <i>inside</i> the wave spring. I just cut a blue bumper down to do the job.

A good resource: http://www.pentestone.com/paintball/MagPump.html

[Lee]

try an RT bumper.

[sbpyro]

I will give it a try and post up a reply when I get it working
Thanks Strider and Lee

[sbpyro]

Thanks for the help
don't have a camera otherwise would post a picture of the monstrosity.