installing a magazine cap detent ball and spring on a 870

[mbogo3]

I have a 870 wingmaster that has the newer Express style type of barrel fixture. The barrel has the empty factory hole for the old style detent ball and spring.Where can I get parts or who can do this or is it worthwhile?I just prefer the older style.

 

[dogzilla]

Brownells sells it all. Spring, pin with rounded end (it isn't a ball). They also sell the staking punch which while you can do without it, it really helps preventing losing the parts across the room if they go boing