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Vector M1 Military
By Bill Mills

The Vector M1 Military is a blowback operated semi-auto paintgun available from Auto Ordinance, the company which presently owns the rights to manufacture and sell the  “Tommy Gun” Thompson Submachinegun which was made infamous as the weapon of choice for prohibition era Chicago gangsters.  The Vector M1 bears no connection to the Vector paintgun manufactured by Air Power in the 1990s.  

The look of the Vector M1 may be very familiar to those who have been playing paintball a while, and remember WARPIG.com’s FAQ for the Viper M1 semi-auto from 1996.  That is because Auto Ordinance has licensed the design from Viper M1 manufacturer, USA Performance Products.  The Vector M1’s parts are made by the same sub-contractors with final assembly being done by Auto Ordinance, and one will find little difference between the two paintguns, aside from the brand name laser engraved on the side (even the same fonts are used for the name.)

The Vector M1 utilizes a stacked tube blowback semiauto design, a concept pioneered in the Promaster and FAST Illustrator paintguns.  This component layout has now become the standard for low cost semi-autos like the Piranha, Rebel and Spyder.  

Unique to the Vector M1 and Viper M1 is the Mag Chamber.  The Mag Chamber is an integrated expansion chamber.  Before compressed air was readily available as a power source for paintball players, many airsmiths solved CO2 chilling and pressure drop problems with add on expansion chambers.  An expansion chamber is designed to perform two basic functions.  First, by gravity, it ensures that liquid CO2 will not feed into a paintgun.  The chamber is aligned vertically, and any liquid CO2 that may get into it from the CO2 tank simply drains to the bottom of the chamber.  The second function is to warm gaseous CO2 to the temperature of the surrounding air.  As CO2 boils from liquid to gas, it absorbs heat from it’s surrounding – this is why CO2 tanks chill under rapid fire, the heat of the tank is being drawn out by the CO2 boiling inside.  The expansion chamber serves to isolate some of the gas away from the liquid, and then allow it to absorb heat.  

Many expansion chambers featured internal and external fins to allow maximum heat transfer.  As the CO2 temperature stabilizes, so does its pressure, enhancing velocity consistency.  The Mag Chamber design takes a slightly different approach.  The chamber is fused to the receiver by a process known as dip-brazing.  Since aluminum is an excellent conductor of heat, the Mag Chamber is able to absorb heat from the entire body of the paintgun in order to combat CO2 chilling.  

Additionally, the Vector M1’s ASA is angled downward at 45 degrees.  This presents a unique point and shoot balance for the paintgun – a loaded Vector M1 balances on a finger through the trigger guard.  The ASA angle serves a more important function through.  It assures that at normal shooting angles, gravity will prevent liquid CO2 from feeding into the Mag Chamber, to maximize its ability to thermally stabilize CO2.  The end result is effective.  The author has used a Viper M1 paintgun in temperatures as low as 28 degrees Fahrenheit with CO2 as the power source, and getting a velocity consistency of +/- 3 fps.

The Vector M1 uses a twist lock barrel system that is unique to the Vector M1 and Viper M1 paintball guns.  To date no manufacturers have produced aftermarket barrels for the Viper M1 in commercial quantities.  While Auto Ordinance only offers the stock ten inch barrel, USA Performance products has sold barrels in a variety of lengths and finishes, under the VXT name which were manufactured by, and to the specifications of, a leading aftermarket barrel manufacturer, giving barrel options for the Vector M1.

The twist lock system offers one of the fastest barrel releases on the market.  Two nylon screws lock into parallel grooves on the Vector M1 barrel.  With a quarter turn to unlock, the barrel slides freely out of the receiver.  As surprisingly easy as it is to remove the barrel, the locking system is reliable, and after years of use, the author has never had a problem with a Viper M1 barrel releasing accidentally on the field.

A wire nubbin style ball detent is built into the Vector M1 barrel.  The detent is held in place with a ring shaped wire clip.  The narrow channels into which the detent and clip fit make changing them and adjusting them a bit difficult, however they are retained securely.  The detent effectively prevents double feeding and operates reliably.  The stock barrel features a removable foregrip (a bicycle handgrip) and three ports approximately two and a half inches from the breech.  Additionally the muzzle is heavily ported with decorative milling channels.

The Vector M1 has a powerfeed design which puts the hopper over the left side of the paintgun.  The powerfeed is attached during the same dip-brazing process used to mount the Mag Chamber.  This leaves a clean, solid bond of metal, rather than the lumpy external welds found on other low cost blowback semis.

Located above the Mag Chamber and below the breech is the Vector M1’s valve chamber.  A knurled plug allows the valve spring, cup seal and valve pin to be removed without any tools required, much like the original FAST Illustrator semi-auto.  

In the rear of the lower receiver chamber is the hammer and mainspring.  The lower rear plug holds the mainspring in under pressure.  Removing the lower rear plug requires removal of the trigger frame.  This is accomplished by unscrewing both trigger frame screws.  These screws are also knurled for tool free removal.  O-rings imbedded in the screw heads make sure that they lock on tight and don’t work loose during play.  Curved slots in the trigger frame screw heads allow a US Quarter to be used as a loosening tool if they are too tight to easily remove by hand.  An important item of note is that the trigger frame screws do not thread into the aluminum receiver.  Instead, they thread into stainless steel inserts that are threaded into the body.  This protects from damage that can occur with cross-threading of the stainless steel screws into a softer aluminum body.  On Viper M1 paintguns the stainless inserts are locked into the receiver with a thread locking compound.  On the Vector M1 reviewed however, the rear insert was not locked in place, and came out while removing the trigger frame.  It is important to ensure that it is properly threaded when reinstalled to prevent damage to the receiver.   

With the trigger frame removed, the lower rear frame screw unscrews by hand.  This allows removal of the mainspring.  When reassembling the lower receiver, the white line laser engraved on the lower rear plug must be vertical – this ensures that a hole in the plug will line up with the rear trigger frame screw, which locks it in place.

In order to remove the hammer, the cocking knob must be unscrewed from the left side.  Normally this part is kept finger tight, but in case it is too tight to remove by hand a hex wrench can be used.  The cocking knob also serves as a tool to remove the pin, which links the hammer to the bolt.  The knob is inserted into a hole in the top of the receiver and screwed into the top of the pin, then used as a handle to pull it out.  The Military Version of the Vector M1 paintgun features a raised sight rail.  Because this rail sits over the link pin removal hole the sight rail features a pair of access holes designed to facilitate removal of the link pin while the rail is in place.  Unfortunately the cocking knob is too short to make this task practical, so either a longer 10-32 screw is needed to pull the pin, or the sight rail must be removed.  

With the link pin out, the hammer slides easily out of the rear of the receiver.  The bolt will slide forward out of the breech area if the barrel has been removed.  The hammer of the Vector M1 is made of hardened steel to prevent against chipping, and it is nickel plated for rust protection.

The Vector M1 features a Delrin bolt.  A pair of urathane o-rings help seal the bolt’s gas port to the receiver, and a single buna-n o-ring seals the bolt to the barrel’s breech.  An aluminum cupped venturi style bolt face is wedged in to the front of the bolt, replacing the diffuser pin and rubber “foamie” bumper found in the original Viper M1 design.

At the rear of the hammer and bolt stroke the bolt bounces off of a black rubber bumper mounted on the Military version’s telescoping stock.  On the standard version, this bumper is mounted on a threaded upper rear plug.  This bumper is critical to the operation of the Vector M1.  It may be tempting to remove the stock of the Military version and operate with no rear cap, but doing so will lead to damage to the lower plug as the hammer will impact against it.  

In addition to the Mag Chamber, the valve design of the Vector M1 contributes to its ability to provide velocity consistency at low temperatures.  The cup seal valve is pressed closed by gas pressure in addition to the valve spring pressure.  As the pressure drops, the valve stays open longer, compensating for the drop by an increase in the volume of gas released.  Instead of adjusting velocity by changing spring pressures, the Vector M1 has a gas flow restriction adjuster.  A hex head screw on the left side of the receiver allows the user to screw the flow adjuster inward, restricting the gas flow between the valve and the bolt.  By not changing spring pressures to adjust velocity, the spring pressure remains adequate for proper recocking.  Cocking the hammer of the Vector M1, it has a heavy feel compared to many paintguns, but this strong spring pressure is an important component to its cold weather performance.

Another significant change between the Vector M1 and newer Viper M1 paintguns and the original Viper M1 is found in the trigger group.  Instead of a narrow trigger with a trigger shoe, the newer model paintguns feature a wider, aluminum trigger.  The reason for this trigger came not from finger comfort, but from the addition of a spring loaded latch inside the trigger.  This latch allows for more consistent resetting of the trigger against the sear with a weaker trigger return spring, giving the newer models a lighter trigger pull than the original Viper M1.

The Vector M1 trigger frame attaches to its grip with an M-16 style lug arrangement.  The original Viper M1s shipped with a Lone Star Ordinance M-16 style grip that had a closeable compartment to store spare o-rings.  The Vector M1 ships with a non-branded hollow M-16 style grip.  Because of the M-16 style attachment a variety of grips built for real firearms can be mounted on the Vector M1.

Fully assembled, the Vector M1 Military package bears an overall resemblance to an AR-15 military rifle, though it does not have the same size or weight.  For scenario style paintball players this look can be attractive, and the ability to slide the telescoping stock out for stability when longballing helps with accuracy.  Sliding it in gets it out of the way for bunker to bunker action giving it practical appeal as well.  For paintballers who play in cold weather and only have access to CO2 as a power source, the all weather reliability of the Vector M1 gives it further practical advantages.  Adding the Thompson name, and distribution by Auto Ordinance which already does business with numerous gun and sporting stores world wide, the Vector M1 stands poised to reach out to a new customer base for paintball.

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