The Annihilator is a converted sheridan gun. It is a pump gun that was/is known for it's extreme accuracy. They were originally not made by MAC1, but after a year or maybe two MAC1 bought the production rights and started making them. This was back in the late '80's. MAC1 has been making them every since. He still has around 30 barrels left, so that's probably how many he'll make, I don't think the Annihilators are in as high a demand as they once were.
Basically the Annihilator is a constant air, direct feed sheridan that has been worked over. Valve job, new barrel with direct feed, delrin pump, new bolt, and side air feed.
My Annihilator is being built on a pgp, but I'm sure that they can be built on other guns, I know they have been built on kp's too.
FOr more info, go to the article section on pgpog and look at the "The Care and Feeding of Sheridan Paintguns". THe long barreled pump is an annihilator.
You can also email Tim McMurray at tim@mac1airgun.com
or visit the website: http://www.mac1airgun.com/
The website is more for pellet gun owners. From talking with Tim he is more into accuracy than anything else, one reason he faded out away from paintball was that people were more into high rates of fire and less into accuracy.
Tim's still putting paintball guns together, I can't wait to get mine. An annihilator will set you back about $200, plus your base gun, but from what I hear it will be well worth it.
As soon as I get it in and get a chance to use it I will let you know more. I'll post pics too.