This month's article is by William D. Ehringer, Ph.D. It is being reprinted here with permission from the author.
A MAC History Lesson
By William D. Ehringer
When Gordon B. Ingram first designed his M10 in 9 mm and .45ACP at his Powder Springs Georgia plant, little did he know that this design would be one that would captivate a number of different types of machine gun enthusiasts. His M10, in the early 1970s, embodied the spirit of making things smaller, more compact, and less expensive. He also believed in the philosophy that the fewer the working parts, the less that things can break. His theories are now axioms, as the MAC has become almost notoriously known as the most reliable sub-machine gun ever built. However, because his company and others produced a number of clones of his original weapon, a number of different questions have evolved over models and design features. The most common question (which is really a mistake) is what is the difference between a MAC-10 and a MAC-11 in 9 mm.
For those of you who are into MACs, you know that the
MAC-11 is the .380 version of the gun (Table 1). This question is usually
meant to be, "What is the difference between a MAC-10/9 and a SWD
M11/9?" Since I currently own examples of these weapons, I took the
time to write down the differences and do a little research on the history and
development of the guns and the companies that built them. In no way am I
claiming that this is an all-inclusive list of all the information on MACs. That
topic would be better dealt with in a comprehensive book on this subject.
Rather, this short narrative is intended to give the MAC enthusiast a feel for
the differences and similarities between the two most popular transferable SMGs
There are seven distinguishing differences between the SWD M11/9 and the MAC-10/9, and they are as follows:
The above seven differences are certainly not inclusive of all MAC-10/9s as a number of other companies also made the MAC. I have tabulated some of the differences below and in Table 1 on the manufacturers and lineage of the MAC-10.
Military Armament Corporation (MAC), based in Powder Springs Georgia from 1970-1976 was the first company to commercially produce the MAC Model 10 (MAC-10).This is the company started by Gordon Ingram that designed and built the first MAC (now you know where the name came from). MAC marketed a number of different weapons, but the MAC-10 (chambered in 9 mm and later in.45 ACP) and the high cyclic rate (approx. 1600 rpm) MAC-11 (chambered in .380) were its mainstays. MAC declared bankruptcy in 1976 and went out of business. A number of factors led to their demise, but the big reason was that little or no military interest in the MAC was generated. MAC sold its tooling and assets (registered and unregistered frames, and parts) to another Georgia-based company called RPB in 1977.
RPB (which has been rumored to stand for Rape, Plunder, and Burn) made the MAC in the same calibers as did the Powder Springs Plant, but in some collectors eyes the manufacturing was not on par with the original MAC. Nearly all of the machine guns that came from RPB were either frame flats, frames or completed guns which were bought from MAC in the auction. Because the machine gun market at that time was not as popular as it is today, RPB came up with a new marketing strategy, which was to offer the MAC-10 as a Title I weapon (a semi-automatic) creating an Open Bolt semi-automatic firearm. BATF stepped in mid-1982 and halted the manufacture of open bolt semi's because they were easily convertible to full-auto. About a year later, RPB went out of business.
SWD Incorporated. In 1983, Wayne Daniels, a former principal at RPB Industries, started his own company. He modified the existing MAC design and created the SWD (Sylvia and Wayne Daniels) M11/9. The gun was MASS-PRODUCED, and that is the reason that so many are still offered for sale NIB. When the MG ban went through in 1986, SWD sold the rights (or became part of) Cobray. Cobray started marketing the closed bolt design Cobray M11/9. This semi-auto uses the exact same MG receiver as did the SWD M11/9, with only a few exceptions (selector switch not drilled, sear pin, and re-enforcing plates absent). After the Assault Weapons Ban in 1994, the Cobray M11/9 could no longer be made, so Cobray re-marketed the gun with a non-threaded barrel and a mag release as the PM-11/9.
Now as far as original suppressors go, two general types were built: a single-stage suppressor that used Nomex wipes and a two-stage suppressor that was wipeless in design. The two-stage suppressor was the original can made for the MAC. The single stage suppressor came along afterwards and was the one hated by its owners, and later by the ATF. The big reason for this hatred was that for the suppressor to achieve decent sound suppression, the internal wipes had to be replaced after only a couple hundred rounds. This is when Gun Show vendors started selling replacement Nomex "wipe kits." Problem was, that the same vendor would also sell the tubes the wipes fit in, and those individuals who made a suppressor in violation of the NFA ruined it for us all. This is when ATF ruled that any suppressor part was indeed a suppressor and had to be either registered or in the possession of a Class 2 manufacturer. Well as you can imagine, this shut-down the "spare suppressor parts business" and owners of these cans had a "limited life suppressor."
On the other hand, the two-stage suppressor can be easily disassembled and cleaned. It is easily distinguishable from its single stage cousin, because it has a larger tube screwed into a smaller tube, whereas the single stage is just a straight tube. Inside of the first stage of the suppressor (which cannot be readily disassembled) are shoestring eyelet's. The second stage contains an inverted baffle cone, then two spiral-type baffles held in place by an encapsulator. Threaded into the end of the suppressor is the only "disposable part" which is a rubber or wax-type grommet end cap. Going price for a single-stage suppressor is about $125-200, while the two-stage suppressor is in the $200-300 range (depending upon manufacturer and condition). RPB and MAC made two-stage cans, while I believe SWD and Cobray made the single stage cans.
The MAC is a very simple gun to strip. I am going to assume you have a full-auto MAC, and since I own only PS, RPB and SWD guns, I am going to give you the necessary information to strip these SMGs. The Texas MACs are a little different so some steps may need to be fine-tuned in order to get them to work.
First remove the magazine from the gun and make sure it is unloaded. Cock the bolt back and make sure there are no rounds in the chamber (actually this is theoretically impossible in an open bolt gun as the bolt resting in the battery position should ignite the round, but always check and be safe). Remove the front pin (two pin design may require a screwdriver to push the small pin latch off the outer big pin). Remove the upper receiver from the lower receiver by pulling forward. Remove the bolt from the upper receiver by moving the bolt rearward until the cocking knob is centered in the large hole at the rear of the cocking knob race. Pull up on the cocking knob to remove. The bolt can then be removed from the upper by sliding it out the back.
(At this point, you are field stripped and ready to clean the lower and upper components. However, if you want to strip it to parts read on)
Push in on the stock latch button and simultaneously pull the stock rearward and out of the receiver. Using a small screwdriver, push down on the stock latch plunger located under the most rearward pin and push this pin out of the receiver. The plunger, spring, and latch can now be removed. The stock latch is welded to the frame and is not removable.
On the grip, remove the grip screw and grip. Push the magazine catch pin through its hole and remove the magazine catch and spring.
In the trigger group. Pull up on the selector spring (long wire that runs along the left side of the receiver) and pull the selector switch out of its hole. This may take some gentle nudging and holding down of parts. Once the selector is removed, the disconnect (thin piece of sheet metal nearest to the selector switch hole) is free and is removed. Also the sear is now free and is removed. The trigger is held in place by a trigger pin. Gently tap on this pin to remove it (some pins are directional so try this procedure GENTLY on both sides until the pin moves freely; however, all of the SWD, PS, and RPB guns have a trigger pin that removes from the left side). With the trigger pin removed, the trigger can be removed, and the safety is no longer held in place. To remove the safety, carefully tap the safety roll pin free from the safety and remove the plastic safety button. The safety assembly is now free and can be removed (Be careful as the safety has a small spring and detent which can easily be lost).
The bolt strips easily as well. First compress the bolt on its spring assembly about 1-2" to expose the recoil rod. At the tip of the rod is a small roll pin. Tap this roll pin out and carefully remove the spring (Caution: The spring is under a fair amount of force and you should wear eye protection when working on the gun). With the spring removed, the recoil rod/ejector rod assembly can be removed. The bolt only has one working part: the extractor. To remove it, carefully drive the extractor retaining pin out of its hole. I like to use a drift punch that is the same size as the hole, this way the extractor is retained on the punch and I can dictate the "terms" of its removal. Remove the extractor and extractor spring.
The barrel should be removed only when necessary. Before you start, spray some Break Free on the threads for the barrel inside of the upper to help loosen it prior to proceeding. Remove the upper from the gun and remove the bolt. Place the upper on a soft surface and tap the barrel-retaining pin from the RIGHT SIDE, so that the force of removing the pin acts to loosen the barrel (lefty-loosey). Place the end of the barrel in a vice that is lined with rubber or thick leather. Using a large screw driver or metal rod that will fit in the upper receiver forward retaining hole, slowly loosen the UPPER from the barrel (i.e., the barrel remains stationary and the upper is turned). I have had barrels that were easy to remove and I have had some that I swear were welded in place. The key is patience and a good vice.
Re-assembly of the MAC is simply a reversal of the above steps.
In short, the choice of either the SWD M11/9 or the MAC-10/9 is an excellent choice as a SMG, especially as a first time NFA weapons purchase. The biggest complaint about either gun is that they have very high cyclic rates. This is great when you first get the gun, but after the "fun" of dumping $6-8 down range in 1.5 seconds ends, most owners start seeking more "accurate means." Problem is, accurate usually spells expensive and thus MAC-10 and SWD M11/9 owners were left with a bullet hose. However, others and I have developed a means to convert a standard SWD M11/9 SMG into a VERY competitive SMG. In fact, the Slow-Fire M11/9 has beaten out MP-5s, M16/9s, and other rare and expensive SMGs in competition. For a complete description of the conversion plans for creating a Slow-Fire M11, see my write-up on James Kitching's Fun Supply Board at: http://www.tecinfo.com/~jayhawk/m11slow.html or alternatively you can read the even more comprehensive write-up on this conversion in a future edition of Small Arms Review.
In my opinion both the SWD M11/9 and the
MAC-10/9 are great, inexpensive, easily accessorized, and easy to maintain
submachine guns. No matter which one you choose, I can almost guarantee that
shooting it will put a smile on your face.
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