(updated April 1, 2007)
The LRM M169 upper for the AR15/M16 platform is a 9mm integrally silenced weapon. It utilizes a ported barrel approximately 7 inches in length enclosed in a one and a half inch tube. The overall length of the suppressor portion is 12.75 inches. As shown in the following videos, the weight of the upper is 4lbs 3.6 ounces. I removed the Olympic Arms hand guard/rail system as I don’t like that particular brand of rail. The upper comes from LRM weighing 4lbs 4.5 ounces. I added the Eotech 552 F revision red dot sight. The factory upper with the rail left on and the Eotech sight installed weighs 5 pounds. The upper comes from the factory with a ramped 9mm bolt, buffer, magazine block and one UZI magazine converted to work in the 9mm M16 system. As shown in the video, I used a factory Colt 9mm SMG magazine, a Crossfire magazine block (the no longer make the Crossfire magblock). The overall length of the suppressor and upper half come to 21.5 inches.
The LRM 169 upper is designed to bleed gas off the barrel through ports drilled into the
barrel. This allows the shooter to utilize cheap and readily available 115 or 124 grain ball ammunition. The object of this is to not allow the bullet to exceed the sound barrier and exhibit transonic or the dreaded supersonic crack. Also LRM states that using a longer barrel helps to improve accuracy, rather than relying on shorter barrel lengths, such as 4 or 5 inches, to stay subsonic.
LRM sells two version of this upper. One is like the one shown in the video and the other is a 16.5 inch version. The longer version is available so that you don’t have to register your lower half as a short barreled rifle per NFA rules. The longer version has not yet been tested by Silencer Research LLC. The owners manual is available here.
LRM TEST RESULTS
On March 17, 2007, I tested the LRM upper on a factory Colt M16A2 registered lower receiver. I tested 6 types of factory loaded ammunition for ballistics/velocities and for dB measurements. The tests were conducted using the B&K 2209 sound meter with a B&K 4136 microphone calibrated with the B&K 4220 Pistonphone. All equipment has been certified and tested so that it can be traced back to the N.I.S.T standards. The meter and weapon are also placed in accordance with Mil-Std 1474D protocol. The LRM 169 was loaded with 10 rounds of each type of ammo. No jams or weapon malfunctions were noted during the entire test. There is no way to test the LRM unsuppressed as it is an integral upper and you cannot remove the silencer for an unsuppressed reading.
LRM M169 with Winchester Q4172
I shot some older Winchester 9mm 115 grain ball ammo that I have plenty of. LRM says NOT to use the current Winchester Whitebox ammo that they sell at Wal Mart and other sporting goods stores as the powder inside cakes up and is retained inside the silencer. This particular ammo was made way before Winchester started to sell promo ammo at Wal Mart so I thought I would try it. Suppression averaged 128.75dB and velocities averaged 1,000 feet per second. Not one round broke the sound barrier. The suppressed decibel range was 124.5 to 129.5dB. Click the icon to see the video.
LRM M169 with PMC 124 Grain Ball
This is the only 124 grain ammunition that I tried with the LRM. The ammo did well, but one round was supersonic and a couple of them were transonic. The ammunition did well on suppression, as it came in at an average of 125dB with a suppressed decibel range of 123-127dB. The velocities averaged 1054 feet per second. Click the icon to see the video.
LRM M169 with Independence 115 Grain Ball
This ammunition is readily available at my local gun store, so I tried some for this test. The first shot was supersonic and I had some transonic shots in the mix as well. The suppression was typical, but the overall velocities of this ammunition are too fast to be subsonic every time. Average suppression was 128dB with average velocities at 1076 feet per second. The suppressed decibel range was from 124.5 to 129.5dB. Click the icon to see the video.
LRM M169 with Remington 115 Grain Jacketed Hollow Points
I wanted to test a hollow point for comparison sake and I found these at my local Wall Mart. They came in the 100 round “Promo” packs. I am pleased with the overall performance of this ammunition. The average suppression was 126.25dB with velocities at an average of 1025 feet per second. This is a nice trade off on velocities to stay subsonic for every shot. This is very important to me. The suppressed range was 124-127.5dB.
LRM M169 with Wolf 115 Grain Ball
Yes, I know… some of you hate Wolf and wouldn’t run that garbage in any gun you own. But for those of you out there that do buy it, I thought I would include it on the test. Some of the rounds ran a little hot, and there could be the occasional supersonic round. Overall the average suppression was 125.75dB with average velocities at 1051 feet per second. The suppressed range was 122.5 to 126dB. Click the icon to see the video.
LRM M169 with American Eagle 115 Grain Ball
I have added this test to the review as this ammo type is the ammo type that is recommended by the manufacturer. I tested this ammunition on April 1, 2007 and wanted to include the results here. Overall suppression was 126.35dB and average velocities were 1048.66. The suppressed range was 124.5-127.5dB. Click on the icon to see the video.
LRM Chart Results
|Video||Ammunition||Average Feet Per Second||Average dB|
|Winchester Q4172 115 Grain Ball||1000 FPS||128.75dB|
|PMC 124 Grain Ball||1054.7 FPS||125dB|
|Independence 115 Grain Ball||1076.6 FPS||128dB|
|Remington UMC Jacketed Hollow Point 115 Grain Ball||1025.74 FPS||126.25dB|
|AE Federal 115 Grain Ball||1048.66||126.35|
|Wolf 115 Grain Ball||1051.6 FPS||125.75|
|TOTALS||Total of all ammunition tested||1042.88 Feet Per Second||126.68 Decibels|
The LRM M169 upper does well when you find what ammo type it runs on well. Three out of six ammo types tested here would be acceptable to shoot if you wanted to stay subsonic every time. See my other review of this upper vs. the Gemtech Talon upper here.
For fun I have a video of the LRM firing full automatic and also in slow motion. Click Here.
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