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Late 1999 Semi Auto Model Rainmaker

Late 1999 Model two finger trigger

1999 Select Fire Rainmaker - Image courtesy Brass Eagle

Original Rainmaker Exploded View

Original Rainmaker

Original Rainmaker

Todd Thomas (Team Brass Eagle) shooting a Rhino Joe Extreme Rainmaker at the '98 Zap Am Open.

Bill Mills (Team Brass Eagle) shooting his R2K Rainmaker at the '98 Zap Am Open.

Bill Mills' Rainmaker 2000 (R2K)

Brass Eagle Rainmaker FAQ
V1.03 By Bill Mills All content, except where noted, Copyright 1999.  All rights reserved.
Contributors: "Ronin", Dave Brisco, Aaron Alexander


The Brass Eagle Rainmaker was unveiled at the 1997 Zap International Amateur Open and represents Brass Eagle's move into the upgradeable tournament level paintgun market.  Prior to the Rainmaker the Brass Eagle line included the Raptor, which fell short of most tournament player's needs, and the high end Angel, imported from England's WDP - priced out of the reach of many players.  The Rainmaker entered the market competitively priced with paintguns like the WGP Autcocker and the Airgun Designs Automag.

What are the key features of the Rainmaker?

The Rainmaker is electropneumatic, that means that it uses electronics to control gas powered operation. From the factory, the Rainmaker is capable of high rates of semi-automatic fire.  Early 1999, Rainmakers were manufactured select fire allowing the user to access full automatic and 3 round burst modes.  In Summer 1999, select fire was discontinued in favor of a return to semi-automatic.  It features a bottom line gas connection and operates on CO2 or compressed air.  The main regulator is adjustable and controls the Rainmaker's velocity.  The pneumatics regulator features a fixed output, and is used to power the Rainmaker's cocking ram.  Some people have mistakenly stated that the Rainmaker is a "double regulated" design.  It is not.  Only the main regulator adjusts the pressure of the gas used to propel the paintball.  Double regulating the Rainmaker requires adding an external regulator, or using a compressed air system (which has a regulator built in).  The Rainmaker fires from an open bolt position.  The electronic timing of the Rainmaker allows the bolt to remain closed for a precisely determined amount of time.  The The Rainmaker has little to no blow back (it won't even blow a business card off of its feed port when the barrel has a barrel plug in it).  Also, due to the low pressure of the operating ram, and the short time duration it is activated, the Rainmaker rarely breaks paintballs.  If a paintball partly feeds into the chamber, it often is bounced in by a tap of the bolt, and then fired on the next trigger pull.

What are some of the pros and cons of the Rainmaker?


  • Electro pneumatic operation means precise timing control.
  • Low cost compared to other electropneumatic paintguns.
  • Uses readily available batteries rather than expensive custom battery packs.
  • Accepts WGP Autococker style barrels.
  • Light, crisp trigger pull.
  • Low pressure cocking is gentle on fragile, thin shelled paint.
  • Vertical feed design for fast rates of fire.
  • Loud compared to other paintguns.
  • Limited availability of after market components.
  • Many airsmiths not yet familiar with Rainmaker.
  • Maximum rate of fire not as high as some other electropneumatic paintguns.
  • The "look" of the rainmaker is unappealing to some.
  • Convertible to select fire.

Is the Rainmaker really an electric Autococker?

No.  While the Rainmaker features the same barrel threading as a WGP Autococker, in order to allow the use of popular aftermarket barrels, these two paintguns are of rather different designs.

Is the Rainmaker really an electric Vector?

Yes and no.  The Rainmaker does use the basic operational design of the Vector, however it improves upon it with electronic timing, and also has other many other advantages, the chief amongst which is interchangeable parts.  The Vector had several parts which had to be custom machined for each individual Vector, where all of the Rainmaker's parts are fully interchangeable. Initially, Brass Eagle representatives stated  that the Rainmaker was developed completely "in house", independent of the Vector.  However the Rainmaker patent, which is public record, is filed under the name of Nick Lotacko.  Lotacko was the designer of the Vector for Air Power.

How does the Rainmaker Operate?

The Rainmaker features a two chamber design.  The upper chamber consists of the bolt, breech and barrel, while the lower chamber consists of the valve, ram, lower bolt, and hammer.  At rest, the pneumatic ram is pushing the lower bolt toward the back of the paintgun.  The upper bolt is connected to the lower bolt by link pin, and thus is also in its rearmost position, allowing a ball to fall into the breech, where it will await a firing action.  A spring wire detent, or "nubbin", keeps the ball from rolling forward into the barrel.  At this point, the lower bolt is compressing the mainspring against the hammer, the sear (which is attached to the hammer, and pivots to latch or unlatch from the lower bolt) is latched to the lower bolt.  When the user pulls the trigger, they close an electrical circuit, which sends a signal (a trigger event) to the electronics board inside the grip frame.  The electronics board then activates the 4 way solenoid valve.  Under electronic control, this valve releases gas from the front of the ram, and applies gas to the rear of the ram.  The ram contracts, pulling the lower bolt, upper bolt, and hammer forward.  At the forward end of the stroke, the bolt is closed and sealed, and the sear hits on a pin which releases it from the lower bolt.  The mainspring pushes the hammer back into the valve, releasing enough gas to fire a shot.  The velocity of the shot is not adjusted by changing spring pressures, but rather by changing gas pressure from the main regulator. After a pre-determined delay, (long enough for the ball to exit the barrel), the control circuit resets the electric 4 way, returning it to its rest state.  This vents pressure from the rear of the ram, and applies it to the front, pushing the lower bolt to the rear, re-compressing the hammer spring, and moving the bolt back to accept the next ball. 

If the Rainmaker is electronic, is it vulnerable to water damage?

While Brass Eagle does not recommend submersing the Rainmaker in water, it is not bothered by dampness or water that a paintgun is likely to run into during normal use.  While reviewing the Rainmaker for Action Pursuit Games magazine, the author directed a stream of water from a garden hose at it for a full 5 minutes with no ill effect.

Does the Rainmaker require compressed air?

No.  The Rainmaker will operate on CO2.  It will, however have better shot-to-shot velocity consistency, and more immunity to temperature changes when running on compressed air or double regulated CO2

How many shots per second does the Rainmaker fire?

In normal semi-automatic mode, Brass Eagle claims that the Rainmaker is capable of firing at up to 14 shots per second.  In real world use, rates of 10 or more shots per second, are not uncommon, but depend of course on the capabilities of the player behind the trigger, and trigger adjustment.

What about full automatic?

In the summer of 1998, Brass Eagle released a number of pre production select fire boards.  These boards feature 3 modes of fire, semi-automatic, 3 round burst, and full automatic.  The three round burst fires a series of three shots, regardless of how long the trigger is held back.  The full automatic mode fires when the trigger is pulled, and continues to fire shot after shot until the trigger is released (or until the gas supply runs out).  The delay between the shots in 3 shot and full auto mode is adjusted by dialing a variable resistor which adjusts from 4 to 10 shots per second.  The mode is selected by removing two screws and pulling back the grip, then setting a switch inside the grip frame.  Because a tool is required to change modes, these boards can easily be locked into semi auto in order to be field legal where full auto is not allowed.  The drawback to this selection method is that where 3 round burst and full auto are allowed, the user must stay in one mode for a whole game, rather than have the luxury of switching modes during play.  The select fire board was produced on early 1999 Rainmakers.  With the advent of the two finger trigger (mid-1999 model) the Rainmaker returned to semi-automatic only.  Because the Rainmaker is electropneumatic, select fire conversions are practical as an aftermarket upgrade, and a number are expected to come to market in the year 2000.  It is important to note that as of spring 1999 the use of full auto and burst modes is under discussion by the ASTM, and insurance companies.  These modes may not be allowed at many or most paintball fields, so any select fire conversions should include a "field lock" so that they may not be changed out of semi-auto mode without the use of tools.

What are the differences between a 1999 Rainmaker and previous Rainmakers?

The early 1999 Rainmaker can be immediately identified by its compact black rubberized pneumatics shroud.  Unlike the older plastic shroud which required the removal of several screws to open, the new shroud simply slides on and off.  It consists of a rubber grip material on an aluminum frame.  The new shroud is possible because of the new power supply.  The select fire boards  (standard on the 1999 model) are voltage regulated to operate on a single 9 volt battery, rather than 4 "AA" batteries like the original Rainmaker.  The select fire board also adds a small red LED (light emitting diode) in the rear of the grip which lights each time the Rainmaker fires.  This serves as a trouble shooting aid ("Am I out of gas or are my batteries dead?") and could potentially be tapped to operate an "on demand" agitating loader like the Turbo Viewloaders used with the Smart Parts Shocker.  The select fire board The early 1999 model also features a "sleep" mode.  It does not draw power when it is not in use, so the power switch has been eliminated from the design.  Some see this as a drawback, as the power switch acted as an additional safety device.  The remaining major difference of the early 1999 model is the newer barrel.  No longer just a straight tube, the stock Rainmaker barrel features porting to reduce turbulence and sound, as well as cosmetic milling.  It is based on the Jacko Infinity series barrel design.  Also, the new models feature a full size gas line from the bottom-line to the regulator, replacing the microline.  The late 1999 model lacks the select fire feature of its predecessor, but adds a cast metal (rather than plastic) two finger trigger with a full hand trigger guard.  This feature makes it readily identifiable as a late 1999 model.  Internally, the trigger activated a push-button similar to the original Rainmaker (the early 1999 model had a lever switch that left extra slop in the trigger pull).

Where can I get aftermarket barrels for the Rainmaker?

The Rainmaker uses the same barrel threads as WGP Autocockers and Snipers.  You can go to pretty much any paintball store, and get aftermarket autococker barrels that will fit and work great on the Rainmaker.

What other aftermaket parts are available for the Rainmaker?

While there is not a plethora of products built specifically for the Rainmaker, many "generic" products will work with it.

  • Foregrips: By drilling the screw hole on the front of the grip frame to a larger size (normally this hole is not used, it is a "leftover" because the grip frame design is based on the Raptor grip frame), foregrips for the Automag can be installed.  These include the Armson folding grip, Benchmark barrel plug grip and others.
  • Bottom lines and HPA cradles:  These can be installed on the grip frame using standard mounting screws.
  • Air systems and accessories: The Rainmaker's bottom-line accepts standard ASA valve CO2 bottles, or connectors.  This means remote lines, HPA systems, etc., are plug and play.  The Rainmaker's regulator features input ports on both the right and left sides so that the micro-line from the bottom line can be moved to either side.  The unused port makes an excellent location for a pressure gauge to help set secondary regulators, or HPA system pressures.
  • Gas manifold: According to Nathan Greenman of Brass Eagle, when the VXT Icebox was shown at the 1998 Zap Amateur Open it was the first aftermarket product for the Rainmaker.  The Icebox fits in place of the regulator and allows the use of a Unireg, or other aftermarket regulator as an upgrade from  the standard regulator.  The Icebox was designed by the author of this FAQ.  Additionally, Xodus Paintball produced a regulator cap that allows the stock regulator to be gutted and capped.  It can then be fed from an aftermarket regulator mounted remotely, bottom-line style, or in a vertical ASA on the front of the grip frame.
  • Valves:  AKA Performance Products has a number of products, including a Rainmaker Tornado Valve and bolt geared for low pressure operation.  The Author of this FAQ has used the AKALMP Lightning Bolt and found it to be efficient enough to allow a noticeable decrease in operating pressure while maintaining the same velocity. 
  • Hardened components: Xodus Paintball produces a titanium oxide lower bolt, and hardened steel bolt link pin designed to have a longer service life than the original parts.
  • Grips: The grip frame is a .45 style and will accept grips like those from Pearce Grips, or Smart Parts.
  • Shrouds: One of the features of the original Rainmaker that many people do not like is the large plastic shroud that houses the batteries and pneumatics.  Many airsmiths have replaced these shrouds with Autococker pneumatics shrouds from Worr Games Products.

Who Builds Custom Rainmakers?

While undoubtedly many airsmiths can and will build custom Rainmakers, the first to build a real reputation for it is "Rhino" Joe Turner.  Rhino Joe's Extreme Rainmakers come with a variety of options including low pressure springs, double triggers, no shrouds, custom bolts, splash anodizing, cocker shrouds, select fire, and inverted foregrip cradles.  Drop Zone Paintball has started building custom Rainmakers designed by Galen Adams and Ken Farris.  Xodus Paintball has also developed a leading name in the Rainmaker world with both accessories, and "Painmaker" custom Rainmakers.

Can the Pre 1999 Rainmaker be switched to a 9 volt battery?

Yes, changing from 5 AA batteries to a single 9 volt is a common modification, especially for players who have removed the stock foregrip and or replaced it with an Autococker pneumatics shroud.  Neither the stock electronics board, or the early Brass Eagle select fire boards (pre 1999)  are designed for 9 volt use, and will not function properly on 9 volts.  A common solution to this problem is for players to only use 9 volt batteries that are slightly used, and thus not putting out their full capacity.  A more professional approach, is to install a fixed output voltage regulator in-line with the battery.  Radio Shack carries a 6 volt fixed output voltage regulator as a special order item (RSU 11392008).  This voltage regulator is very inexpensive (about $1.50 plus shipping) and requires only minor electronics experience (some soldering) to install, as does a 9 volt battery clip.  Howard "Heretic" Allen has written a tech guide on how to install this voltage regulator.  To read it, click here.

What options are there for trigger jobs?

Because of the Rainmaker's electronic firing system, the options for trigger jobs are as varied as the types of electrical switches that exist.  Any single pole, normally open, momentary switch can be used to replace the switch that sits behind the Rainmaker's trigger.  Lever type micro switches are quite popular as they provide a positive "click" feel when activated, and provide very little physical resistance.  Rainmakers with the select fire board feature a lever action micro switch as a component of the board.  Replacing this switch requires a bit more experience with soldering and de-soldering printed circuit board components.  Because of the similarity between the Rainmaker's trigger frame, and the trigger frame of a Brass Eagle Raptor, 2 finger triggers built for the Raptor can be installed on the Rainmaker with a minimum of modification.

How can a Rainmaker "cheat the chrono"?

This information is included in the FAQ not to assist cheaters, but to inform field staff and referees.  Increasing paintball velocity past field limits is not only unethical (cheating to gain an advantage) but it is hazardous.  Beyond 300 feet per second the risk of subcuateneous injection (paint, dirt, and bacteria being pushed under the skin through pores and tears) increases, as does the chance of goggle lens failure (paintball goggles are designed for use with paintguns firing at or below 300 fps).  The Rainmaker, like all paintguns must be chronographed multiple times per day during use.  Some "renegade" paintball players on private land do not use chronographs citing the expense (they are available for under $100).  A chronograph costs much less than a glass eye. 

Turning the Rainmaker's main regulator body counter-clockwise will decrease its velocity. A player could potentially "cheat the chrono" by setting their Rainmaker for a high velocity with the velocity screw, then turning it down by twisting the regulator body 1/4 turn before chronoing on or off the field.  On field, a twist of the regulator body would result in a velocity boost.  It is imparative, when chronographing the Rainmaker that the regulator body be screwed completely into place.  If the regulator body is screwed completely into place, the only thing a player can do by unscrewing it on the field is to decrease velocity.

What are some common problems and how do I fix them?

  • Ball detent out of adjustment - If the ball detent does not reach far enough into the breech, the Rainmaker will double feed resulting in balls breaking in the barrel and or wildly erratic velocity changes.  With the gas turned off, and no hopper in place, drop a single ball into the breech, and tilt the Rainmaker forward at a 45 degree angle.  If it the ball rolls forward past the detent, adjustment is needed.  Remove the screw that locks the detent in to the side of the receiver.  Remove the detent, and bend it slightly so that it protrudes a little further into the breech.  Reinstall and retest.
  • Ram mis-alignment - If the pneumatic ram is askew, friction with the lower bolt and receiver wall will keep the Rainmaker from closing the bolt and firing, and or from returning the the bolt to the rear position.  Remove the shroud, and loosen the two screws that lock the ram into the receiver.  Wiggle the ram, and make sure it is seated flush against the receiver, retighten the screws and reinstall the shroud.
  • High velocity - Sometimes in warm weather (90F+) when using CO2 the Rainmaker may have trouble adjusting to less than 300 feet per second velocity.  Switching to compressed air (which includes a secondary regulator), adding a secondary regulator (Unireg, Stabilizer, etc.), or replacing the stock regulator with an adapter (Icebox) and aftermarket regulator (Unireg, Stabilizer, etc.) can provide better pressure control to achieve the necessary velocity setting.

What is the future of the Rainmaker?
In 2000, Brass Eagle dropped production of the Rainmaker.  Several dealers, including Drop Zone, still actively support the Rainmaker, and spare parts are available, making used Rainmakers still a cost effective option for players to get into an electropneumatic paintgum.

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