Although the "Copperhead Special" built for me by Casey Sullivan of Triple-Fiction Productions in Florida (firstname.lastname@example.org) still has the basic, familiar shape that would immediately mark it as some sort of ST:V/VI Assault Phaser, if you place it next to the Playmates Toys version of the Assault Phaser from the '90s, it quickly becomes clear that the Copperhead has different proportions, repositioned layering and significantly reworked features & control surfaces, making it a distinctive variant design. This was done deliberately to simplify the prop and give it a more angled, dynamic appearance.
This photo was taken before the following was done, but as of 09/01/2013, two minor alterations have been made to the Copperhead Special (named for the fact that its unique color scheme is based on the colors of the Sig Sauer P238 Copperhead .38ACP pocket pistol) variant of the ST:V/VI Assault or "Burning" Phaser pistol.
The knob underneath the levers near the top of the pistol grip has been painted silver to match the other silver fittings, but the most important cosmetic alteration is also somewhat more subtle. The original Copperhead Special had a barrel that was entirely painted in the same shade of silver. This detracted a bit from the realism of the weapon in that it didn't look like there was a hole in the barrel.
I wanted to fix that, but at the same time, I felt that applying a flat black paint marker to the barrel tip was overkill; so instead, I pulled out a metallic gray paint marker and a metallic silver paint marker. I lined the angled rim of the barrel tip with the metallic silver while the flat front end of the barrel was painted with 3 coats of metallic gray.
At first glance under normal room lighting, it doesn't look like there is any difference. But upon closer inspection, in a mirror, under brighter lighting or under flash photography, it just becomes apparent that there are actually three different shades of metallic silver/gray on the weapon barrel, allowing for the illusion that the barrel is hollow inside.
I should be getting the Assassin Phaser Rifle variant in the mail soon, and I can't wait to see these props side-by-side.