This shows my red dot shimmed to fit my new (to me) Atomic.
The sight fits my HW45 perfectly but the 45 has an oversize rail, when I tried it on my Atomic it was off centre so I used the steel spring strip out of an old windscreen wiper rubber.

Two sections the right length were cut with tinsnips, 2 minutes with a Dremmel put the angle top & bottom on the strip which fits the dovetail mount, the other was left unmolested.

This is what it looks like assembled -

http://i135.photobucket.com/albums/q...obOnAtomic.jpg

It's rock solid, pulls down flat to the gun, is perfectly centered and took 20 minutes from unpacking to shooting, don't throw those old wipers away, newer ones don't all have stainless springs!
Enjoy!
Nick