Originally Posted by Zippaye
The auto trigger cam basically works as a safety that lets go when the pump handle moves forward. Its connected to the pump arm with a lever.
So you have that cam in the trigger frame and as u move the pump handle back the lever moves the cam so the sear is locked in the upright position. As you move the pump handle forward the lever moves forward moving the cam into the forward position allowing the sear to move and releasing the hammer
Excellent description. With that description in mind make sure the flat side of the cam is facing the trigger.
The lug was also mentioned, if the lug is backed out too far the marker will shoot as normal but when the AT is used the sear will not grab the lug. The lug is adjusted with an allen wrench. First you need to put an allen wrench into the velocity adjuster so it engages the set screw on the hammer. Back it out half a turn or so. Now you pull the bolt and use an allen wrench to turn the lug down into the frame. You will be able to see the lug through the bolt pin slot.
Basically after you check the AT cam position see if it works. If it does not work correctly you can follow the steps below. This is how I set my AT.
I set my lug so I have my trigger pull as short as I can. Now I try my auto trigger. If the AT does not grab I give the lug a 1/4 turn. If the AT works as you want it to lock down the set screw in the hammer and go play.
Many people who want to try pumps are getting these markers with no knowledge of how to work on them or tune them. They then get frustrated and sell them. It sounds liek this is what happened in your case.
I did the same thing that you did. I purchased a used purple Sniper. It was a mess when I got it. It needed to be cleaned, lubed and tuned. The previous owner had been shooting CO2 through the gun as well. The CO2 wont hurt the gun but it is not the most consistent power source.
After a little work and some tuning this marker is a serious paint slinger. It is called the Purple People Eater at my home field. It is very accurate, quiet and with the AT has a very nice ROF.
Basically get to know your gun and get it tuned in to where you like it. Try different springs in the pump handle. Eventually get a spring kit and play with the valve and hammer springs.
You can also PM me if you want some more help.