By Dan Shea
A crowd thinks in images, and the image itself immediately calls up a series of other images, having no logical connection with the first. Our reasoning shows us the incoherence that is in the images, but a crowd is almost blind to this truth, and confuses with the real event what the deforming action of its imagination has superimposed there-on. – Gustav le Bon
The above quote from Gustav le Bon is offered without further comment, in regards to the current frenzy of protesters regarding the War in Iraq. We need our national will sapped again while we are in harm’s way about as much as we need these peaceniks to tell us how to negotiate with terrorists.
On to the gun questions.
Raffica special: Link weights for fast counting.
Since the ending of the magazine ban, a lot of interesting links have been coming onto the market. The guys in the shop at LMOLLC had to sort out five pallets of links, and we decided to share the weights of the links for posterity. Remember to subtract the weight of your container before calculating how many links you have.
Left: M15A2 link. (51.31 lbs; 23.27 kg per 1,000 links) Push through link for the M85 .50 caliber machine gun.
Top center: M2/M9 link. (38.6 lbs; 17.51 kg per 1,000 links) Pull out link for the .50 caliber M2HB, M3 machine guns.
Top Right: M1 link. (10.12 lbs; 4.59 kg per 1,000 links) Pull out link for the .30 caliber Browning machine guns. .308 caliber Israeli links weigh almost the same, very minor difference.
Bottom center: M13 link. (9.57 lbs; 4.34 kg per 1,000 links) Push through link for .30 caliber M60, M240 machine guns.
Bottom right: M27. (4.50 lbs; 2.04 kg per 1,000 links) Push through .223 caliber link for the Minimi, M249, Shrike, CETME Ameli, etc. Stoner 63 links weigh the same.
Q- Dan, in your article on Living History in Serbia, you mentioned the Yugoslav M80 as their version of the RPG. It looks more like a version of our M72 LAW.
A- What I actually said was that the M80 is the Yugoslav version of the Russian RPG-18, which is quite a different animal from the infamous RPG-7 series. The RPG-18 is very similar to the US M72 series “LAW”. Nothing really touches the versatility of the reloadable RPG-7 in most arsenals. The fact that many countries have gone to a lightweight, short, expendable rocket propelled grenade launcher hasn’t diminished the prevalence of the RPG-7. As noted in the article we ran on the Iranian offerings at the Defense Services Asia 2004 show in Malaysia (SAR Vol. 7, No. 12, Page 55), the cut off RPG-7 the Islamic Republic of Iran DIO is offering on the world market can give the M72/RPG-18 style launchers a run for their money in concealability and their RPG-7 “short” is reloadable to boot. Scary prospect considering some of Iran’s international customers.
Regarding the M80, it is longer than the RPG-18 by about 150mm, and has a more extended range as well. The RPG-18 has an effective range of 200 meters; the US M72 about 220 meters and the M80 is beyond 250 meters effectively. All of these can fire much farther of course, but sights and the nature of shoulder fired rockets are the limiting factors for accuracy. The RPG-7 has grenades that can be fired accurately out to 550-600 meters with reasonable accuracy and a skilled operator well trained with the optical sight. Note that in the picture the M80 rocket motor is significantly larger than the RPG-18, and the M80 has six fins instead of the four fins on the RPG-18 or the eight fins on the US M72. It has been my experience in firing these that the M80 is equivalent to the US M72 series in performance. There are variations within the M72 series that have differing penetrations, just like there are differences in the rounds used for the RPG-7.
Penetration in Rolled Homogenous Armor (RHA) varies by projectile, but the one-shot launchers all perform about the same. The Russian RPG-18 claims 375mm of RHA penetration, the M72A5 LAW claims 355mm of RHA penetration, and the Yugoslav M80 claims only 300mm of RHA penetration. From personal observation, I would put the M80 penetration up with the best of the other offerings.
There are numerous examples of these expended tubes in private hands, and the RPG-18 is the hardest one to collapse back into carrying configuration. If you extend the tube, pay attention as you do each step. There have been a number of articles written recently on the RPG-7 system, and there were many inaccuracies in these. SAR will be running some thoroughly vetted out articles on these weapons systems in the near future, but Raffica is not the place to get too deep on this.
Q- I was going through a gun show and found this tool in a pile of parts. The parts were M16 and some other military looking parts. Can you ID this for me? It is about 3-1/2 inches long.
A- Sure, that is the M249 Scraper Tool. I took a better picture of one, and decided to identify the various tools on it. These have been around for a long time, and there is a pivot pin on the base of the gas regulator scraper section that allows the tool to fold up and fit in a flat spot in your gear.
Q- In the last issue of SAR, you went over the M56 parts sets that are for sale right now. I bought one that I am making into a semi-auto, but only have one magazine. I can’t seem to locate any more. Can I use the PPSh41 magazine for this?
A- Hold on a second – no point in ruining a perfectly good PPSh41 magazine even though it is the same caliber and general body shape. They are a bit rarer than the M56 magazine. Take a good look at the accompanying picture. The PPSh41 magazine has brackets welded on the side to stabilize it against the receiver for round presentation. These would have to be removed to allow this magazine to enter the magazine well on the Yugoslav M56, as well as cutting a notch for the magazine catch. Additionally, the PPSh41 has extended ribs at the front and rear that would have to be ground down to fit in the M56 magazine well. While the body size and shape is very similar, the PPSh41 body is about .03 inches shallower and some of the ribs could be left on to compensate if needed. Looking at the feed lips, there is plenty of metal to work with on a PPSh41 magazine to remove and contour for the M56 feeding. However, the followers are of different contour, and this might present issues on feeding. All in all, I think it wiser to wait a bit for more magazines to come in to the US as there should be more coming in as surplus.
Q-I keep hearing about the complexity of suppressor baffles used in sound suppressors. When I took my “XYZ” suppressor apart, the baffles were like washers with a cone pressed into them. What’s the big deal here, what makes the suppressors I see offered from many manufacturers so costly?
A- Like most things, it is never as simple as it looks. A good estimate of the costs of developing a new suppressor design is $250,000 in research and development. What you have been looking at is very old technology; which is fine for some civilian applications. These simple baffle designs take the edge off of the sound pressure waves, enough to satisfy the general shooting public with their already butchered hearing thresholds. All of us have high frequency hearing loss, and many times we can stand around at a range testing a suppressor that is “quiet” to us, while every dog for miles is barking and anyone who hasn’t had twenty years of shooting experience is covering up their ears in agony. The physics of sound as it relates to human hearing is something that requires a larger forum than a Raffica question. Instead, we present some photos of a cutaway suppressor to show the complexity and design needed on one fairly modern suppressor system, and Dr. Philip H. Dater of Gemtech and Antares Technology has agreed to give a brief response as well. Take it away, Phil.
“The suppressor technology of the 1960s and early 1970s was generally that of a mesh to rapidly absorb heat, thereby reducing the sudden pressure release associated with firearm discharge. Examples are the Welrod, High Standard OSS, MAC-Ruger pistol of the Vietnam era and others. These tended to be extremely compact suppressors and were almost always built around a ported barrel (which controlled velocity). They also had an exceptionally limited lifespan, usually less than 500 rounds. In the late 1970s and extending throughout most of the 1980s, the technology shifted to far longer lived and slightly larger suppressors using baffles. As a rule, these baffles were simplistic by today’s standards, many of which were simply flat fender washers spaced in a tube. Some used flat washers that had been formed into a shallow cone with a forming die, while others used machined baffles. Spacing was uniform and generally not optimized other than the thought was that the more baffles present, the greater surface area for heat absorption. What was common among the designs is that the baffles were symmetric and generally all the same, leading to simplified production techniques. These functioned at reducing pressure by having a moderately large surface area to absorb heat and a relatively large volume for expansion.
The structure of the baffles provided primarily for large surface areas for heat absorption as well as some degree of trapping of gases. The most prolific manufacturer of this technology was Jonathan Arthur Ciener, who started the mass marketing of suppressors in the US civilian market. The JAC baffles were shallow cones with integral spacers machined from aluminum on either screw machines or primitive CNC lathes. Automatic Weapons Company followed soon thereafter with stamped baffles in the majority of their suppressors in the early and mid 1980s. Combinations including this technology are still seen today in some of the older designs manufactured by more modern companies.
Starting around 1988-1993 and progressing to the current day were baffle designs that were far more complex. One of the leaders was Doug Olson (RKI 001), working for Qual-a-tec under some generous research grants that lasted several years. While the newer designs of this era still had a lot of surface area for heat absorption, various holes, jets, and asymmetric structures were introduced to generate turbulence in the gas flow, delaying and slowing gas exit from the suppressor. At this point, rotational orientation of the baffles with respect to each other became important in the performance of the suppressor. Because of the higher efficiency of the baffle, it became possible to significantly reduce the size of the suppressor while at the same time increasing its performance. The commonest (and most widely copied) baffle today is the so-called K-baffle, so named because in cross section it resembled the letter “K.”
(Photo by Dan Shea, Courtesy HK)
There have been, of course, significant overlapping of designs. Hiram Maxim, known as the father of firearm silencers (and amateur radio), was a silencer visionary and a design genius before his time. His designs, dating back to the early 1900s, used stamped baffles with significant asymmetry that were relatively compact. Parker-Hale has used a similar design. The WW2 De Lisle silenced carbine and the silenced Sten used a combination of meshes and simplistic stamped baffles. Many of the older designs were predicated by the tooling readily available.
Suppressor design continues to evolve. Availability of CNC machining centers, improved casting techniques, and accurate sound level meters has made refining designs and prototyping new concepts easier, although it remains dreadfully expensive. Design is hampered in this country by restrictive legislation and an exorbitant excise tax limiting the civilian market. Because of governmental restrictions, the market is artificially small, and the selling price has to compensate for the R&D expenses as well as increased unit cost of more limited production runs. If there were no restrictions, far less expensive manufacturing techniques could be employed with lower cost to the end user (as in most of Europe today).” – Dr. Philip H. Dater
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| This article first appeared in Small Arms Review V9N5 (February 2006) |
