Introduction to the 68AutoMag



[1] The 68AUTOMAG can be broken down into pneumatic components and mechanical components. Pneumatic components are explained fully in this manual since they relate directly to function and maintenance. All mechanical components are listed for identification. Most mechanical components are not explained since they are not critical to proper functioning of the paintball gun. Those mechanical components that need explanation are detailed.

[2] Pneumatic components are:

[3] Mechanical components consist of: Valve Body
[4] The Valve Body is a critical component of the 68AUTOMAG. The Valve Body is easily identified by the Air Hose attached to it. Installed correctly, the Valve Body screws into the Regulator so that the 68AUTOMAG logo on each part lines up.

[5] The Valve Body Hole is on the bottom of the Valve Body. The On/Off Valve Assembly fits into the Valve Body Hole. At the bottom of the Valve Body Hole, placed in before the On/Off Valve Assembly, are two o-rings pressed within each other. The two o-rings prevent CO2 escape past the On/Off Pin and through the On/Off Valve Assembly. The inner of the two o-rings, the Valve Body Hole Small O-ring, is an active o-ring made of teflon. The outer of the two o-rings, the Valve Body Hole Large O-ring, is an inactive o-ring made of urethane.

[6] The On/Off Valve Assembly is used to control the flow of CO2 between the Regulator and the Air Chamber. The On/Off Valve Assembly consists of the On/Off Top, On/Off Bottom and On/Off Pin. Located in the Valve Body Hole and moved by the Sear, the up and down movement of the On/Off Pin seals the Regulator from the Air Chamber. To prevent CO2 escape, the On/Off Valve Assembly uses two o-rings. The On/Off Bottom Large O-ring is an inactive o-ring made of urethane. The On/Off Bottom Small O-ring is an inactive o-ring made of white teflon.

[7] The Air Chamber receives the measured charge of CO2 from the Regulator. When the Air Chamber vents, the CO2 gas expands through the Power Tube and pushes the Bolt forward. Level 7 paintball guns have slightly larger air chambers than previous models to decrease the pressure within the chamber and reduce paintball breakage. In Level 7 paintball guns, the Power Tube is welded to the Air Chamber. The Air Chamber cannot be opened.

[8] The Regulator is the heart of the 68AUTOMAG. The Regulator, as the name implies, controls the pressures within the 68AUTOMAG and therefore the velocity.

[9] The Regulator Body is at the rear of the paintball gun and screwed into the Valve Body. The air seal is maintained between the Regulator Body and the Valve Body by the Regulator Seal and the Regulator Body O-ring. The Regulator Valve with the Regulator Valve Spring is used to close the Regulator from the Air Source. Located on the bottom of the Regulator Body, the Regulator Body Detent Pin is a small metal pin which slides into the Z-shaped Slot in the Rail. The Regulator Body Detent Pin is designed to prevent the Valve Body and Regulator from springing back clear of the Rail when the Field Strip Screw is removed.

[10] The Regulator Piston is inside the Regulator Body. The position of the Regulator Piston is adjusted by turning the Regulator Nut which compresses the Regulator Spring Pack. By moving the Regulator Piston, the pressure of the CO2 in the paintball gun and thus the velocity is controlled.

[11] The Regulator Piston also contains the Blow Off Valve. The Blow Off Valve vents off any overpressure in the Regulator or Air Chamber. The Blow Off Valve is factory set for approximately 550 psi and is not user adjustable. If fired when venting, at the factory pressure setting, the paintball gun is firing at approximately 340 fps, an unsafe speed.

Power Tube
[12] The Power Tube delivers the blast of discharged CO2 from the Air Chamber to the Bolt. The Power Tube contains the Power Tube Spring and the Power Tube O-ring. The Power Tube Spring holds the Power Tube O-ring in place to seal the Air Chamber.

[13] The Power Tube Insert is made of brass and screws into the Power Tube. The Power Tube Insert is open on the end which allows the central shaft of the Bolt to slide into the Power Tube, through the Power Tube Spring and against the Power Tube O-ring to complete the seal on the Power Tube.

[14] Held in place by the Sear, the Bolt sits overtop the Power Tube and blows forward when the paintball gun is fired. The central metal shaft of the Bolt slides into the Power Tube to seal the Power Tube from the Air Chamber until the paintball gun is fired. Because replacing a bolt is easier than a sear, the Bolt is made of a softer material than the Sear. Eventually, the Bolt will wear along the edge where the Sear rests. A worn down edge will prevent the Bolt from locking in place and the paintball gun will go fully automatic.

[15] The neoprene rubber Foamie is designed to cushion the paintball as it is pushed past the Nubbin into the Barrel by the Bolt. The Foamie is the only part of the paintball gun that will require regular replacement (generally once a season). The Foamie is glued to the front of the Bolt using a commercial super glue.

Bolt Spring
[16] The Bolt Spring is made of high tensile square spring steel. A squared spring was chosen to help in seating the Bolt Spring onto the Bolt. Installed over the Bolt, the Bolt Spring compresses as the Bolt moves forward. When the CO2 escapes the Bolt, the Bolt Spring expands and pushes the Bolt back to where the Sear can catch the Bolt.

Back Bottle Adapter
[17] The Back Bottle Adapter is attached to the rear of the Rail by two screws and is the attachment point for the CO2 source. It is also used to deliver lubrication to the internal components of the paintball gun.

Air Hose
[18] A braided metal Air Hose delivers CO2 from the Back Bottle Adapter to the Valve Body. An external hose was chosen so that the design of the 68AUTOMAG did not require an internal CO2 delivery passage. An internal CO2 delivery passage would require constant resealing when the paintball gun was broken open for maintenance. The Air Hose is connected by brass fittings that remain sealed during normal maintenance. This limits the chances of a leak from the Air Hose.

Air Source
Do NOT use a siphon type constant air tank. Liquid CO2 will damage the seals and o-rings.

[19] The 68AUTOMAG can be used with any standard source of CO2 either constant air tank, 12 gram or back bottle pack, provided the source can be attached to the paintball gun. The Air Source used must be able to feed CO2 fast enough into the 68AUTOMAG to support rapid firing.

[20] The O-rings used in the 68AUTOMAG are all made from either high quality 90 durometer urethane or teflon. The O-rings are designed for long life and abrasion resistance. The O-rings were selected for easy access and interchangeability.

[21] O-rings are classed as either active or inactive. An active O-ring continuously seals and releases CO2. An inactive O-ring only continuously holds CO2 pressure.

[22] All active O-rings are accessible without tools, still, removing the O-rings without a tool may be difficult. If a particular active O-ring starts to wear and a replacement is not available, the active O-ring can be exchanged with an identical inactive O-ring from another portion of the paintball gun. It is highly unlikely that inactive O-rings will ever wear or leak, but, they can be traded with their identical active counterparts on the field if necessary. Swapping a leaking inactive o-ring into an active position is not recommended since active o-rings are critical to the paintball gun working correctly.

[23] The standard Barrel on the 68AUTOMAG is made from aluminum stock. The Barrel Lock Pin is a stainless steel detent pin mounted in the Rail. The O-rings on the Barrel serve to give the Barrel a friction fit. The Barrel O-rings do not seal air pressure.

[24] A wire Nubbin prevents double feeding. The Nubbin is woven in a machined channel on the barrel upper surface and held in place by the Barrel O-rings. A properly installed Nubbin protrudes about 1-1/2 to 2 thicknesses of a matchbook cover into the breech of the Barrel. The Nubbin will automatically compensate for all size paintballs and should give long life if not abused.

Loader and Elbow
[25] Included with the 68AUTOMAG is a 90 round VIEWLOADER and Elbow. Under ideal conditions, the Loader provided can feed paintballs at a maximum rate of seven per second. The plastic Elbow connects the Loader to the Ball Feed Tube on the Main Body. To permit maximum feeding, the Elbow should be smooth on the inside and without sharp edges or corners. Any obstructions will cause the paintballs to hangup in the Elbow and Loader.

[26] There are many brands of paintballs on the market; all with different specifications. Differences in shell thickness, shape, fill colour and fill density will result in performance differences. Low quality paintballs will work poorly in the 68AUTOMAG. With a properly set up paintball gun using quality paint, users can expect to break only three to four paintballs per thousand. Low quality paint will break one in 50.

[27] Paintball breakage is caused two ways: poor feeding or impact. Poor feeding will result in the paintball not being fully in the breech and the bolt cutting the paintball during firing. Impact comes either from the bolt or from CO2 blast. When the Foamie is damaged or missing, the Bolt will break the shell of the paintball. Blast from the CO2 will break thin shelled paintballs.

[28] A good test for paintball shell strength is to drop a few paintballs, one at a time, from a height of six feet. Paintballs that consistently survive six or seven bounces are considered fresh. Paintballs that break within three bounces are either stale or have weak shells.

[29] If the Foamie and the Nubbin are in good shape and the paintball gun still experiences breakage problems, switching paintball brands or colors within a brand may solve the problem because the paint batch has changed. Experimenting with different type of paintballs and colors will decide the best paintball for each individual 68AUTOMAG and playing conditions.

Accessory Rails
[30] There are two Accessory Rails molded into the side of the Rail for mounting various accessories. The Accessory Rails can hold anything that would bolt to a regular sight rail.


[31] The 68AUTOMAG is a semi-automatic paintball gun using the design idea of blow forward from an open bolt. The action takes place in three stages: Regulation, Chamber Fill and Chamber Dump.

[32] Regulation begins when an Air Source is connected to the paintball gun and the pneumatic system builds up pressure. At a predetermined pressure, set by the Regulator Nut, the Regulator Valve closes and seals off the Air Source from the remainder of the paintball gun. The pressure in the paintball gun is now approximately 400 psi though the air source pressure may vary from 600 to 1000 psi under different temperatures depending on the air source used.

[33] Chamber Fill, the second stage, happens when the Trigger is released. The On/Off Valve Assembly opens and allows the Air Chamber within the Valve Body to fill from the Regulator to a regulated pressure of 400 psi. To prevent flow into the Power Tube, the forward seal of the Air Chamber is created by the Power Tube O-ring and the central shaft of the Bolt.

[34] Stage three, Chamber Dump, is the critical phase. The air chamber design is like a champagne bottle with a cork stuck in the opening. The Bolt, like a cork, wants to pop forward, but the Sear holds the Bolt in place. Pulling the Trigger pushes the Trigger Rod which tilts the Sear. The Sear first closes the On/Off Valve Assembly shutting off the Air Chamber from the Regulator. This gives the paintball gun a precise amount of regulated CO2 charge within the Air Chamber. The Sear next releases the Bolt. The CO2 pressure pushes the Bolt forward and breaks the forward seal of the Air Chamber. Like a cork moving out of the bottle, the Bolt starts moving forward into the breech area. The Bolt pushes the paintball past the Nubbin into the Barrel. As this has been happening, CO2 has been entering the Power Tube, expanding and moving through the Power Tube Insert and the front face of the Bolt. The escaping CO2 blows the paintball down the Barrel and out into the atmosphere. As the Bolt moves forward, it compresses the Bolt Spring located in front of and around the Bolt. After all the CO2 escapes the Bolt, the Bolt Spring expands and pushes the Bolt back into the starting position where the Sear locks the Bolt down again and reseals the Power Tube from the Air Chamber. Releasing the Trigger begins the process again by opening the On/Off Valve Assembly and filling the Air Chamber from the Regulator.

Design Deficiencies

[35] As with all designs, the design of the 68AUTOMAG is not perfect. There are inadequacies in this design caused by using regulators and using CO2. Airgun Designs, Inc. is investigating using alternate technology and power sources.

Using Pressure Regulators
[36] All pressure regulators, by the nature of their design, cannot fill a chamber instantly. Regulators must fill most of the chamber quickly then taper off to reach the desired pressure. Chamber Fill on the 68AUTOMAG takes roughly 1/3 of a second. Because of the Regulator tapering off, when firing the paintball gun faster than three shots per second, the Air Chamber will not fill fully and the average velocity will drop by 10 to 20 fps.

Using CO2
[37] The other problem revolves around the CO2 itself. Usually thought of as either a gas or a liquid, in reality CO2 takes the form of steam. Like water, CO2 boils when heated and becomes a steam. The CO2 steam will still exist in a moist form until its temperature is above 87 F (31 C) at normal atmospheric pressure. Boiling temperature of any liquid is affected by the pressure; higher pressures raise the boiling temperature, lower pressures lower the boiling temperature. Firing rapidly lowers the pressure in the Air Source and causes the CO2 to boil at a lower temperature than normal. The CO2 steam then enters the Air Chamber. The Air Chamber empties when the paintball gun fires and lowers the pressure yet again. The steam in the Air Chamber boils into a gas and expands its volume by 30 times. The result is velocity variation in firing the paintballs. Placing a warm Air Source onto a cold paintball gun will allow warm CO2 steam into the paintball gun where the steam will condense into a liquid in the Air Chamber. When the Air Chamber empties, the liquid rapidly boils off and results in a dangerous overspeed shot (See Part 1, Para 11.).


[38] Using the 11 inch barrel, the 68AUTOMAG will get an average of 400 good shots from a 7 oz. constant air tank under normal conditions. Using a twelve gram source will usually give 20 good shots if time is allowed between shots for pressure recovery. Firing 5 paintballs per second using a 12 gram will give 10 to 13 good shots. Using a longer or shorter barrel will affect the gas efficiency and change the number of good shots from any CO2 source.

Cold Weather
[39] 68AUTOMAG performance at temperatures below 40 F (4 C) will be poor because gas pressure is affected by temperature of the gas. Since the paintball gun is designed to function at a predetermined pressure, temperatures below freezing will not generate sufficient air source pressure for adequate velocity. Some method of keeping the Air Source above freezing will be necessary, but this increases the risk of warm CO2 condensing in the cold paintball gun and dangerous overspeed shots.

Rate of Fire
Rates of fire higher than 6 shots per second may result in feeding problems. The standard VIEWLOADER supplied with the paintball gun can only feed 7 paintballs per second under ideal conditions.

[40] The average person can fire 4 to 5 shots per second due to the 68AUTOMAG trigger mechanism. The trigger mechanism was designed for the highest rate of fire possible. Trigger takeup, the distance the Trigger is pulled before moving the Trigger Rod, has been kept to a minimum. Charged with adrenaline in a game situation, a person may increase their rate of fire to 6 shots per second.

Updates and Upgrades

[41] Airgun Designs, Inc. is constantly pushing the leading edge of paintball technology and making refinements in their paintball guns. As a service to the customer, the company offers updates and upgrades to keep the customer and the paintball gun at the forefront of paintball technology and firepower.

[42] Updates are changes that improve the original design or function of the paintball gun. For one year from date of purchase, Airgun Designs, Inc. will provide to registered owners free updates.

[43] Upgrades are options that add new features to the original design. A few examples are specialty barrels, differing air hose lengths, front bottle adapter kits, left feed main bodies and power feeds. Upgrades are available from the company at a reasonable cost.

[44] Contact Airgun Designs, Inc. at (708) 520-7507 or Fax (708) 520-7848 for information on the latest updates and upgrades available. If sent a self addressed stamped envelope and the serial number of the paintball gun by the owner, Airgun Designs, Inc. will return a complete history of that particular 68AUTOMAG.

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