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A member here has one - he posted a review. What interests me is how they taped them up with electrical or friction tape. I've seen pics that look suspiciously like the end is taped off as well, which I would normally consider a dangerous practice, but one layer of tape? Maybe not. It would act as a wipe and possible quiet the first shot even more. I'd love to hear about this more from some VN vets.  Here's one of the pics that make me question this:

http://i62.photobucket.com/albums/h92/Morg308/sontag25.jpg

Quoted:
What interests me is how they taped them up with electrical or friction tape. I've seen pics that look suspiciously like the end is taped off as well, which I would normally consider a dangerous practice, but one layer of tape? Maybe not. It would act as a wipe and possible quiet the first shot even more.

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The moderator was a pretty lousy silencer, which anyone could infer from its size alone. I shot them side by side with a 14.5" A1 carbine at a special operations school in 1981 or 1982, bearing in mind that the original 177 was very old and worn by then. There was not a lot of difference in the sound, but the 177 was definitely quieter than the newer carbine. Just not much quieter –– not enough to make it safe to shoot without earpro in my opinion.

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It would be interesting to find some db comparison between the different length barrels with standard FH vs. moderators.

The sound pressure level was measured according to Mil-Std 1474D, which specifies A-weighting.  Weighting degrades meter performance to match the frequency response of the human ear, and A-weighting is accurate and appropriate only for sound levels below 55 dB.  For sound levels above 130 dB, and in particular in the 160+ dB region of the non-suppressed 5.56mm rifle, the measurements should be performed without any weighting (also called “linear” or Z-weighting, depending on the meter manufacturer’s designation).  While there is a rough correlation using A-weighting between uncorking pressure and measured sound level, the sound measurements are not considered overly accurate due to compliance with the Mil-Std.

Sound levels are pressure measurements expressed as a logarithmic ratio of the actual pressure referenced to 20 micro-Pascals, the threshold of human hearing.  There was a little less consistency in the sound measurements than in actual uncorking barrel pressure measurements, partially because of adding several more variables.  These included the acoustic impedance of the air and wind direction/velocity.  In addition, the inaccuracies in this sound intensity range by using the called-for A-weighting introduces some level of inaccuracy that would probably not be seen in unweighted measurements.  When pressure is plotted against sound pressure level in decibels and sound pressure level is plotted against barrel length, there is slightly more deviation from the projected average, but the trend and general correlation is statistically meaningful.  Actual sound pressure levels varied from 162.5 dB(A) in the 24-inch barrel to 165.1 dB(A) in the 5-inch barrel.

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http://www.dtic.mil/ndia/2010armament/WednesdayCumberlandPhilipDater.pdf

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You guys are too ate up with retro!  I like retro stuff too, but if I'm going through the trouble and money, I want something that makes things quieter.  Just my opinion.

http://www.ar15.com/media/viewFile.html?i=22921

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Well, you can still build an E1 middy - I really considered this seriously, but Olgunner has been a bad influence on me. I don't regret spending more on my Remington Rand than I would have for a RIA, so I figure the same thing here. I mean, I'm 50 and not getting any younger. If I'm going to SBR anything, it's now.