Enhancing strength of magnet, practical question

I feel like I'm shooting a squirrel with a howitzer asking my question on the physics stack exchange, but here goes...

I have a long ring-shaped (1cm outer dia x 3cm length) rare earth magnet that I want to have move through a brass tube, moved by a magnet a few mm from the outside of the brass tube. The magnet has a steel screw going through the middle of the ring that attaches to something else. The magnet is polarized along the length of the magnet.

1. Is the steel screw that runs through the center of the magnet reducing the strength of the magnetic field?
2. Will putting a steel plate behind the brass tube (perpendicular to the polarization) increase the strength of the magnet system? I know that putting a metal plate on one pole of a magnet will increase its strength.

Thanks for your help. I'm a real dunce with physics, assume it's magic.

Edited to address the below question: I'm trying to build a spring-loaded magnetic latch. See a diagram below of the latch. To release the latch, I hold a magnet outside the brass tube so that it attracts to the magnet inside, and then I move the magnet to the right. This moves the screw out of the hole in the catch plate. I want to maximize the amt of force I get from the magnets so that I can use a pretty stiff spring (in order to ensure that the latch stays securely closed when not being opened.)

• You may be better off to use a tube made of a non-conductor instead of brass as this will prevent eddy current being produced in the tube which would produce forces opposite the the direction of motion of the magnet? m.youtube.com/watch?v=5BeFoz3Ypo4 – Farcher Apr 27 '17 at 13:08