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Ravi's Paintball Place


Inside the Micromag II

© Ravi Chopra, 1996
Printed in Action Pursuit Games, May 1996

And here's the header for the Micromag Infosheet I was going to write, but never got around to it.


Table of Contents


Micromag History

The Micromag was first conceived in the minds of Forest Hatcher (President - Pro-Team Products/Gun F/X) and Doug Zander (Vice-President - Gun F/X) in the Fall of 1993. The original concept was a super-light, super-short version of the popular Airgun Designs '68 Automag for speedball. The first ones made (the "Stage I" Micromags) were actually cut-down Automags, so short they required remachined barrels to stay in the radically shortened bodies. Though this custom conversion enjoyed some popularity, the two felt they could improve on the idea.

With this in mind and a little help from Airgun Designs, they set out to do just that. The result arrived in the Spring of 1994 as the '68 Micromag conversion kit. It had an aluminum body, fixed 6" gun-drilled barrel, power-feed, anti-doubler, and '45 grip frame. All it needed was an Automag A.I.R. valve, bolt, and sear to become a complete, functioning, speedball-dominating machine. In late Summer 1994, Pro-Team Products was licensed by Airgun Designs to sell a complete paintgun, complete with it's own A.I.R. valve with "'68 Micromag" laser-engraved in the side.

How good was it? Try, good enough to tie with the Bob Long Signature Series Autococker for 1st runner up Semi-Auto of the year in PCRI's 1994 special edition.

It may have been the Micro's excellent speedball performance that ultimately harkened a call for change. Many players, thrilled with the light-weight and high rate-of-fire started taking their Micromags into the woods where the limitations of the fixed 6" barrel began to show. While it was surprisingly accurate for a barrel so short, its range and efficiency suffered in the woods when compared to its longer-barreled competition. Players began asking for a longer-barreled variant, or better yet, a removable barrel so they could pick their favorite. So Forest and Doug went back to work. The latest product of their labors debuted at the 1995 Knoxville Indoor Championship where Team Sasquatch finished 5th (the highest placed amateur team) playing exclusively with Micromag II's.


The '68 Micromag II

The '68 Micromag II's design builds on the successful features of the fixed barrel Micromag. Like the original Micromag, it is extruded and machined from 6061 T-6 aircraft-grade aluminum. There was originally some concern that the aluminum construction might not be up to the task of surviving the constant pounding of the blow-forward bolt, so a stainless steel insert was incorporated at the bolt contact point to prevent mushrooming and cracking. Also carried over from the original design are a Pro-Team anti-double feed, '45 grip frame, and Minimag-style power-feed. The power-feed is held on with an allen-screw, allowing it to be quickly and easily replaced with an available straight-feed for those who prefer to sight down the barrel.

New for the Micro II are a bottom-line ASA, integrated sight-rail, mount-point for a vertical ASA, and Autococker-compatible barrel threads! The stock removable barrel is an aluminum 8" smooth-bore with flared end-construction to dampen resonant vibrations. All the hoses and fittings included with the Micro II are attractively nickel-plated. Combined with the custom-milled body, the result is a very slick looking paintgun.

Though most Micromag II's are now sold as complete 'guns (with AGD A.I.R. valve, bolt, and sear), it is still available as a conversion kit for those who already own an Automag or Minimag.


Operation

Those of you familiar with the '68 Automag and '68 Minimag can skip this section. With the same internals, the Micromag works in the exact same way.

The Micromag is an open-bolt design. That is to say, at rest the bolt is in the retracted position, leaving the breech open to the feed port. It differs (with the Auto and Minimag) from the rest of the vast field of open-bolt paintguns in being a blow-forward design. Blow-back designs adjust velocity by metering the volume of gas fired by either varying spring tension or the size of the bolt-hole. The 'mag is unique in that it fires a fixed volume of gas and controls velocity by varying the pressure. The obvious advantage of this is more consistent velocity since the pressure is held steady, even with changing tank pressure.

Pressure into the paintgun is regulated with the Advanced Integrated Regulator (or A.I.R. valve as it's commonly called) at the back of the 'gun. The pressure, and thus the velocity, is adjusted by turning a large allen screw at the back of the regulator, clockwise to increase, counterclockwise to decrease. Fixed pressure gas passes forward from there, through an on/off valve and into a fixed-volume chamber behind the bolt. When the 'gun is gassed-up, pressure forces a pin in the on/off valve down, rotating the sear forward to where it catches the bolt. When you pull the trigger, the back of the sear first pushes up on the on/off pin closing the flow of gas into the chamber behind the bolt. Then the front of the sear drops off the bolt and the high-pressure gas throws it forward, pushing a ball into the barrel and firing it. Since the pressure behind the bolt has now been vented, a heavy bolt-return spring snaps the bolt back into the starting position. Release of the trigger first catches the bolt, then opens the on/off valve for recharging. This process is so fast, the Micromag will easily fire as quickly as you can squeeze the trigger. And since the required pull is so short and light (more on this later), you can pull it very very quickly.

I know that this all sounds terribly complex. But when you actually take one apart and see how it works first-hand, you see that it is actually a very simple and elegant design. So much so that it allows any 'gun designed around it to be smaller, lighter, and faster than just about anything else available.


Performance

Let's face it, when it comes right down to it, performance is the most important characteristic of any paintgun. A paintgun can be well-priced, look sweet, and have all the options, but if it doesn't perform it's not worth having. But what is performance? I'd argue that it goes much further than just range and accuracy. Weight, balance, trigger-feel, efficiency, reliability, and overall "feel" are all important performance characteristics. If the 'gun doesn't feel right to you, you're not going to be happy with it no matter how straight or far it shoots.

So how does the Micromag II perform? The answer you probably think I'm going to give is "just like an Automag", but you're wrong. While the Micro does have some characteristics in common with the Airgun Designs semis, it is significantly different in many ways.

The Feel

The first thing you notice when you pick up the Micromag is the weight. With all-aluminum body and frame construction, this paintgun is extraordinarily light. At 2 lbs., it undercuts even the Automag by ~2 lb. And since the regulator is situated right over the top of your hand, it is almost perfectly balanced. Running a remote gas-delivery system I've found the Micromag easy to fire steadily and accurately even one-handed. The first day I took it out to run it through its paces, I found myself running full-tilt cross-field, firing downfield on an opponent one-handed. Not only did I have no trouble keeping up a high rate-of-fire, but I was shooting accurately enough to keep my target flopping around on the ground like a fish out of water. Naturally, using your other hand to stabilize the 'gun brings a greater level of stability and accuracy.

The next thing you notice is the '45 grip frame. It is somewhat fatter than the stock Automag frame, and comes down at a slightly different angle. The nice thing about this is that it "points" much better. That is to say, when you hold your hand out naturally, pointing your index finger where you want to shoot, the barrel is right on target. I also feel like I get a better grip on the '45 frame.

The '45 frame also provides a significantly different trigger-feel. In all 'mags, there is a rod attached to the bottom of the sear which couples it to the trigger. In the Auto/Minimag, the rod contacts near the center of the back of the trigger, right behind the point against which your finger pulls. The '45 frame puts that rod against the back of the top of the trigger so you're pulling at a spot below the rod contact point. The result of this is that the trigger pull is slightly longer, but significantly softer than with the standard 'mag frame. I found that I could fire the 'gun faster while holding a steadier aim since there wasn't such a hard snap at the fire point. It also felt like the Micromag had less "kick" (less tendency to twist up and back when it's fired). Since the Micromag shares all its moving components with the Auto/Minimag, I have no idea why this should be. Forest has postulated that it might have something to do with the hard-contact of the Micro's threaded-in barrel rather than an o-ring friction fit. However it is achieved, this adds to the Micromag's exceptional stability despite its light weight.

The Features

My favorite design innovation of the Micromag is the integration of body and rail into a single unit. I wish I had a dollar for every time I heard someone complain about a bent rail throwing the 'gun out of alignment, or a worn sear-pin channel allowing the sear to slip and the 'gun to misfire. The Micromag's body and rail are constructed from a single piece of aluminum, assuring proper component alignment. Additionally, the sear slides up through a slot in the bottom of the body and is retained by the sear-pin slid through a hole drilled through the side of the body, assuring that the sear can never slip.

The power-feed works as well as always, keeping the blow-back inherent in the design from blowing balls up the feed tube. Additionally, the power-feed tube is situated a bit higher and has a slightly shorter tube so it situates the feeder close to the center of the paintgun. This may not sound like a very big deal, but when you consider the weight of a full VL2000 (or worse yet, a VL3000), you quickly realize that this does a lot to improve the lateral balance and stability of this very light paintgun. The power-feed is held on by a pair of rails which slide up into a pair of slots in the 'gun body and is retained by a small screw. As I mentioned before, it can easily be removed for cleaning or replacing with a straight-feed for those who prefer to sight over top of the 'gun.

The ball detente has also been changed. Since it takes Autococker-type threaded barrels, it obviously doesn't have the wire-nubbin incorporated into the barrel. Instead they've installed one of the Pro-Team ball-jocks (also found on Gun F/X Autocockers) on the side of the Micromag. For those who haven't seen it, it's a plastic unit held to the outside of the 'gun with a couple of screws. A spring-loaded arm sticks into the breech and prevents paintballs from rolling forward into the barrel before firing. This prevents double feeding and ball chopping. In addition to being more durable than a thin wire (which can slice every ball after breaking), the plastic arm is 3 mm wide, spreading its force on the paintball over a greater area making it less likely to crack the ball when fired.

Firing

OK, so it feels great in your hand and has some nice performance features to keep it functioning reliably game after game. What you really want to know is: How does it shoot? How does it's range, accuracy, and efficiency compare to the best of the best?

You're going to hate this answer.

It depends on your paint and barrel selection.

Every experienced player knows that even the greatest paintgun in the world suffers if it isn't equipped with a good barrel and quality paint that matches it. Using a barrel with too tight or too loose a bore for the paint you're shooting will drive your gas efficiency into the cellar. In general I found that the Micromag gave pretty much the same efficiency that I used to get from my Automag, given equivalent barrels. That is to say, while it's far from pump-gun efficient, you get many more shots from the Micromag than you'll get from most heavy-hammered blow-forward semis. As with the Automag, efficiency drops with extended rapid-firing (via tank chilling) and with excessive dry-firing (firing without a chambered paintball).

Paint-barrel matching is even more important to the characteristics of range and accuracy. Not surprisingly, I found that my Autococker barrels performed very similarly on my Micromag to the way they did on my 'cocker. I'm not saying that performance was identical to that observed on the Autococker. Rather, the relative performance differences between barrels were pretty much the same when compared on the Autococker and on the Micromag. The moral of the story is, if you have a very good barrel for your Autococker that works well with the paint you frequently use, chances are you'll also be happy with it's performance on the Micro. (Whether the Autococker or the Micromag performs better is a topic I won't touch. Sorry.)

The stock barrel is an 8" aluminum, smoothbore design with no rifling, venting, or muzzle braking whatsoever. Though 8" sounds rather short, it's medium bore and lack of holes and ports allows it to provide the 'gun with decent efficiency. The range and accuracy, while good for short range and speedball games, is going to leave many outdoor and tournament players hungering for more. It simply isn't up to the task of placing paint in small groups at ranges where you're taking full advantage of your 300 fps speed limit. An important note here is that Pro-Team offers the Micromag (and it's barrel) in a variety of satin and gloss anodized finishes. The satin finish is slightly thicker than gloss finish and thus results in a slightly tighter barrel ID. I've had the chance to audition both glossy and satin finished stock barrels, and the satin finish provided considerably better accuracy than the gloss anodization. In short, if you want the best performance without having to invest in aftermarket barrels, you're going to want to buy a satin-finished Micromag (the standard coating is black-satin).


It Ain't Perfect

Well, I've had a lot of nice things to say about the '68 Micromag. It's a damn nice marker. But as with all paintguns, it has it's limitations and imperfections.

One thing you'll notice is that the power-feed sits high enough at the center of the 'gun that it will occlude many sights with standard-height clamps. A sight-raiser will be required to use many sights with the power-feed on this marker. Of course there is no problem if you use the straight-feed.

You'll also notice that there's no really good way to use a pull-through squeegee on the field. While on the Auto/Minimag the barrel comes out with a quick twist-and-pull, the Micro's barrel must be unscrewed the entire way to allow easy access with a pull-through. This is not a quick option. Thus, most Micromag users will have to resort to carrying a stick-squeegee on the field for quick cleans of barrel-breaks.

As with the Auto/Minimag, you'll also find the Micromag to be very liquid sensitive. Getting liquid CO2 into the paintgun can cause seals in the A.I.R. valve and power-tube to freeze up, causing the gun to freeze-up, shoot hot, and just basically act erratically. There are several ways to keep liquid out of the regulator. The first and most obvious is to use nitrogen or compressed air. Those who don't want to shell out the bucks for an expensive nitro system, or who don't have local filling facilities will want to use an anti-siphon tank for bottom-line configurations, a remote system, a vertically mounted tank, or a vertical-mount expansion chamber.

Finally, the manual is sadly deficient. The manual included with my Micromag was just an AGD Automag manual with a new Micromag cover stapled over it. While it does provide adequate instruction on the parts that the two paintguns share, it will be confusing to new players not familiar with their differences and it doesn't elaborate on the new features that the Micromag provides. In my opinion, the Micromag is a new enough paintgun, different enough from the Auto/Minimag to warrant a new manual of it's own.

There is also one point of concern. Early Micromags were designed with relatively tight barrel-threads, made tighter by the anodizing process. While this was designed to give a snug fit to stock Budd Orr barrels and most of the popular barrel designs (Smart Parts, J&J, etc.), some other aftermarket barrels did not fit. Forest Hatcher became aware of the problem and promptly modified the thread depth to accept barrels with larger threads. People who bought one of the earlier Micromags are not out of luck, though. Pro-Team is a very player-oriented company. If you send them your 'gun with the barrels that won't fit, they will open the threads out on your Micro to fit your barrels and return them to you, free of charge.


Options

Pro-Team Products also offers a variety of very cool options and add-ons for the Micromag, allowing you to customize the marker to your particular tastes and style.

Straight-feed: I've mentioned this a couple of times already. It replaces the standard power-feed for improved sighting.

Vertical ASA: Due to the Micromag's entirely different body-rail design, it is not compatible with the AGD Auto/Minimag's vertical adapter. Pro-Team builds a vertical ASA specifically fit to the Micromag.

Expansion Chamber: Pro-Team also makes a matching expansion chamber for CO2 users that threads into the vertical adapter. It is machined with finger-grooves so it effectively doubles as a vertical for-grip.

For-Grip: While the expansion chamber does function as a for-grip as well. It's mass is unnecessary for those running nitrogen. For those who want something to hang onto up front without the added weight of an expansion chamber, Forest has promised a grip that will either bolt directly to the body or thread into the vertical ASA. This should be available by the time this article sees publication.

Accurizer Bolt: This is a replacement 10-hole venturi bolt for any 'mag. It is meticulously machined to AGD specifications to ensure compatibility. The venturi design is supposed to provide a more arcing, "Autococker-like" trajectory. Additionally, it has a gold-colored titanium-nitride coating which is more lubricious (Forest's word, not mine) than stainless steel. The biggest benefit of this coating is that it reduces wear on the power-tube o-ring. Rumor has it that the All Americans have gone to using these bolts.

Power-Tube Spacer Kit: One of the less-known "tunable" parts of the basic Automag design is the power-tube spring length. Too long a spring can lead to leaking down the barrel. Too short a spring leads to bolt-stick and a stiff trigger. This new kit has 5 different-length spacers which replace the power-tube spring. With these, you can replace the spring with a spacer of the exact length to match your 'gun and it's degree of sear-wear.

Armson Internally-Rifled Barrels: These high-performance barrels are available in a variety of lengths as replacements for the stock barrel.

Custom Anodizing: Pro-Team also offers most of their products in a variety of unique gloss and satin finishes, in both solid color and splash patterns. Style conscious paintballers will be happy to know that they can order an entire gun package, from barrel to bottom-line, in the same color or pattern.

Left-Handed Regulator & Body: The latest addition to the Micromag series of products is a left handed version of the 'gun, designed as a mirror image of the right-handed 'gun.


Conclusions

The Micromag is an excellent paintgun. Though it is based off the basic Airgun Designs blow-forward design, it isn't a simple copy with a custom-milled body. With many unique design elements, innovative features, and upgrades incorporated into the Micromag design, the result is an entirely new paintgun with a different feel and performance profile from the AGD Auto/Minimag.

The biggest advantages of the Micromag are it's extreme light weight and it's exceptional balance and stability. Autococker users will find added benefit in being able to use their old barrels with the new marker.

All material at this site is © Ravi Chopra, 1999