Taking the Mystery Out of Timing an AutoCocker

Ever want to get a cocker? Think that they're too much work? It will fail on you when you need it? Think you'll spend more time in the staging area than on the field? Worried that the first time the gun goes down, you'll be lost, and have no way to fix it? To be honest, thats what I had happen to me with my first gun. That was a Tippman Pro-Lite. A very reliable gun, and once I learned what I had to do to keep it running, (like cleaning it, oiling it, putting it to bed on time, etc..) it ran like a champ.

So, can I guarantee that you'll never have a problem with your gun? No. Can I show you how to time a cocker so that the problems will be limited to a few simple things? I hope so, or Iím wasting a lot of time and paper.

That's the reason for this. It will take the mystery out of the single most miss-understood part of the AutoCocker, the timing.

Autocockers work on a very simple principle. Once you understand that, you are halfway home. Auto-Cockers are simply automated pump guns, (the AC uses the same body as the WGP Sniper, a pump gun created by that giant among paintballers, Bud Orr). The front block and components replace the action of you pumping, as well as thinking about it.

The front block of the AC consists of the following parts:

The Four-way Valve (also known as The Three way valve): This is the thinking part of the front end. When you use a pump-gun, you pull the trigger, then pump the gun. The 4-way valve thinks for you. As you pull the trigger, the operating rod pulls the 4-way shaft back. This opens and closes vents in the valve, sending gas to the front or back of the ram. This gas makes the ram push or pull as needed.

The Ram: The ram is a two-sided piston. By using the gas from the 4-way valve, the ram becomes the muscle in your arm, pushing the pump arm back, or pulling it forward.

The Low Pressure Regulator: The regulator on the front of the AC controls the amount of pressure the front end has to work with. It in effect replaces the part of your brain that would decide how hard to pump the gun.

Now, just so we're on the same page......

The Timing Rod: The connecting rod that goes from the trigger to the 4-way valve, pulling it open and closed.

The Pump Rod: The rod that connects the ram to the back block, pumping the gun with the gas from the 4-way valve.

The Cocking Rod: The rod that is located under the bolt going through the back block. This pulls the hammer back when the gun cycles.

The Hammer Lug: This is a small screw that sticks out of the bottom of the hammer, and catches the sear when the gun cycles.

The Sear: The sear is a plate of steel inside the grip frame, that is raised an lowered by the trigger plate to fire the marker.

Now that we know what the parts do, this is how they do it.

When you first gas up the Auto-cocker, all the parts are at rest. That means there are no parts being pushed or pulled by the springs. The hammer is not cocked, and there is no ball in the chamber.

On the first trigger pull, the first half is not used. I'll cover that part latter. The second half pulls on the 4-way shaft, allowing gas into the ram. This makes the ram push against the pump arm, which pushes against the back block. When the back block is pushed back it brings the bolt and hammer with it.

As the bolt comes back, a ball drops into the chamber, the hammer passes the sear, and the rear ward cycle is complete.

As the trigger is released, the trigger is pushed forward by the trigger spring. That in turn pushes the 4-way shaft forward, venting gas to the back of the ram. That makes the ram pull the back block and the bolt (and now a paintball is in the breech, and is being pushed into the barrel). At this point the hammer is caught by the sear, and stays back.

On the next trigger pull, the first half (told you I'd get to it) lowers the sear and lets the hammer go. The hammer hits the valve stem, and opens it to release gas that fires the ball.

Now that things are at rest again, the second half of the trigger pull does the same thing. It re-cocks the hammer, loads a ball into the breach, and when the trigger is released, pulls the bolt closed, sets the hammer on the sear, and waits for the next shot.

We have now covered the basics (and put most of the tourney guys to sleep) lets go onto timing.
If the front end isn't working the way it's supposed to, things can go bad. If you are using a pump gun and you pull the trigger before you pump it, what do you get? Nothing but stronger fingers. What if you pump it, but don't pull the trigger? When you do pull the trigger, the three or four balls you have loaded in the barrel will become one big mess. What about if you pull the pump handle closed too fast, and pinch a ball? Your busted with your squeegee in your hand by the guys that's bunkering you.

The trick to timing a 'Cocker is to get thing to happen in the right order at the right time. The hammer falls, THEN the 4-way kicks in to open the breach, and re-cock the hammer.

The first step is to adjust the back block. You want the back block to have a crack of space between it and the gun body. If there isn't enough space, the ram can rip the steel pump arm right out of those soft aluminum threads. If there is too much space, the ram will hit the seal on the back of its travel, causing a premature leak. If you can fit a piece of paper in the space between the block and body, you are all set. If you can fit a piece of cardboard in there, you have a problem. To adjust the back block, simply take out the cocking rod and bolt, then tighten or loosen the back block on the pump arm.

The second step is to adjust the cocking rod. This rod is the connecting point between your hammer and your back block. The proper setting of the cocking rod is very important in a smooth cycle. Too short, and you over work the ram, and make the gun feel clunky when you shoot. Too long, and the hammer may not reliably catch the sear, causing double feeds, and broken paint.
To set the cocking rod, first make sure the rod is screwed all the way into the hammer. Then un-screw the knob on the end until it is almost all the way off. From the factory, the knob is loc-tited in place, so you will need to loosen it before you can adjust it. Dipping the end of the rod in boiling water for a few minutes will soften the loc-tite, and they you can un-screw the knob, and the set screw inside the knob with ease.
Now, with the knob almost all the way off the rod, pull the back block back as far as it will go. The hammer will be pulled back when you do this. You are listening for a slight "click" as you pull it back. That "click" is the hammer lug being pulled past the sear. You want to hear the click about 1/8" before the back block can no longer be pulled further back. Setting the cocking rod this way will ensure that the hammer is pulled far enough back to catch the sear, but not so far back that it over works the ram. If the cocking rod is too long, the hammer may not come back far enough, and if it is too short, you over compress the main spring, making the ram work harder. If the cocking rod is extremely short, you can also limit the rear ward travel of the back block, and cause the bolt to partially block the feed tube. has two
Once you have the cocking rod set where it needs to be, use a little loc-tite on the cap. This will keep it from loosening when you take the rod out to adjust the velocity.

Now you have to adjust the hammer lug. This is the part that catches the hammer on the sear as the back block travels forward. With the í98 and later models, there is a hole drilled into the top of the gun that goes all the way through to the bottom of the frame. If you have an earlier model, take it to your local airsmith and have him drill it for you, it will save on the headaches. Two notes, on 98 and later bodies, some of the holes are drilled so that the lug cannot be adjusted with gas in the gun. The hammer has to be pushed a little forward on the valve stem to get the hole to line up with the hammer. Also, there are two types of hammer kits, one (used on pre '98 models) uses a set screw that is adjusted with a 3/32 hex wrench, and the other (98 and later, and some after market hammer kits) needs a 1/8 wrench, so if it feels like the hex key is all the way down, but the lug isn't moving, try the other size wrench.

Now that you have found the lug, the right wrench, you set it so the hammer falls just before the halfway point in the pull. If it drops early, turn the screw in, if it falls late, turn the screw out.

If it doesn't fall at all, it's one of two things. First, the lug is turned so far in that the sear never even sees it, or second, the lug is so far down that the sear can't drop far enough to let go. To find out which way you have to go simply push on the cocking rod. If it feels like its hitting a spring when there is no air in the gun, the lug is too far up, (that's the valve you're pushing on). Just slowly lower the hammer lug until it starts to catch the sear.
If it feels rock hard, with no give, that's the sear you are pushing on, and it's too far out. If its too far out, you have to loosen the two screws on the grip, then pull the trigger, the hammer should let go. If it doesn't, take the grip screws all the way out, and GENTLY move the grip away from the body. If you are too rough, you will bend the 4-way operating rod, and that's not good.

Another rant on my part. The 1998 cockers come with a new style trigger plate, The STO style. These don't have the slot for the trigger rod, they have a hole. In my never to be humble opinion, THESE SUCK. They make getting a reliable timing to your gun more difficult, but worst of all, lower the consistency of the gun at the crono.
"How can one little thing change so much?" you ask, looking at me like I'm crazy. Simple, the cocker has to have things happen in order, as covered earlier. Having a slot in the trigger gives time for one part to happen (like the hammer falling) before the next stage begins (like the 4-way kicking in).
On the new models, slowly pull the trigger. On most you will find that the hammer is caught part way, by the back block coming back. That means that the hammer isn't hitting the valve the same way each time, giving bad crono results.
So what to do? Simple, buy a trigger plate with an oval slot in it. I know that K.A.P.P. makes a nice one, as well as many other companies. Take out the old trigger, and put in the new one, then finish the article.
The following has been added on May 12, 2002:
My opinion stated above still hold true, but is a little out of date. On 98 cockers, WGP was still using the old style three ways (the ones with caps in the ends) and that was the cause of the tight timing. The three way limited the over travel of the shaft, and that in turn limited the over travel of the trigger. If you have a three way where the three way shaft can be pulled right out of the front of the three way body, ignore my little rant above.
Now, for something completely different: The rest of the timing article.

Now, on to the 4-way valve. This is the only part where you have to gas up the gun. If you have an older stock trigger rod, this will be a little hit or miss, but if you have the threaded rod, it's a lot easier.
With an older, slip fit rod, loosen the rear set screw on the 4-way coupler, and try sliding it around till you find the right spot.
On newer, threaded rods, loosen the rear set screw, and turn the coupler clock-wise or counter clock-wise to adjust the 4-way.
All you have to do is set the rod so the 4-way opens up after the hammer has dropped. Now that means that the block doesn't move until the hammer has fallen all the way to hit the valve. I use the first 2/5th of the trigger for the sear to drop the hammer, 1/5th as a gap between the hammer falling and the 4-way starting, and the last 2/5th for the 4-way.

That should be all you have to do. If your gun is timed the way you just read, it will develop a slight vacuum in the feed tube when you fire. This will help to keep balls feeding right on time every time.

With a little tinkering, you can adjust the timing to fit your personal preference. If you tighten up the timing, so things happen closer together, the gun will be harder to short stroke (pulling the trigger only part way, and the 4 way valve only halfway, sometimes double feeding paint, or chopping a ball with the bolt), but you loose the vacuum, and if done poorly, will create blow back.

Well, that's about it. Just remember; don't be afraid to play with the timing on your gun. The worst you can do is having to start all over from scratch.
One other thing. Make sure you have a tank with normal pressure in it. If you try to time the gun with a low tank the settings will keep changing on you. Don't ask how long it took me to realize what the problem was with that time. TWO HOURS of slowly changing the timing to adjust for a dead tank, I was ready for a padded room!