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Posted: 12/16/2008 2:26:25 PM EDT
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What kind of brakes or compensators work with the Gemtech HALO?
Experiences? |
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The Gemtech HALO works with most standard NATO flash hiders (A1, A2, HK, FNC, etc.) with slight modification to the Ruger Mini-14, it can be run on those as well. Basically, any mount with 2.05" or less length, 22mm diameter, and held to general NATO specs for concentricity with boreline.
Since the HALO is pretty widely used around God's green earth, there are companies making flash hiders and brakes to have compatibility with its mounting system, as well as some firearm manufacturers putting HALO compatible muzzle devices on their new carbines. VLTOR, for instance, makes an excellent flash hider, and PWS (Primary Weapons Systems) makes their very interesting flash-comp to be compatible with HALOs - generally, the aftermarket brakes and hiders are going to have a tighter fit, which is good for accuracy and repeatability as added benefit over standard A2s and the like. Kel GEMTECH TEAM GUY ARFCOM INDUSTRY DISCLAIMER: I've got nothing particularly witty right now, but I'll give it some thought later. PS: Gemtech HALO somewhere out in the world - Real or airsoft? 
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Of course - there's even been a couple of posters on these fora that have made heavy barrel ARs accept HALO suppressors by turning the heavy barrel down to 22mm for the correct length and then a reduced diameter behind to mimic the rear of the flash hider.
But any brake made to the proper dimensions with an eye on tolerances and parallel to the boreline would work, all common sense applies... Kel GEMTECH TEAM GUY |
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Quoted:
How is the sound reduction of the HALO compared to the M4-02 thread on model? Perceived louder? Is the HALO OK to use indoors without hearing protection? Blow back differences between the two? These are the types of questions that, sadly, nobody will answer any more. The history is long, sad, and complex, but you won't get an answer to these types of questions from GemTech. |
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Quoted:
Kel Last group of questions... for now anyway. How is the sound reduction of the HALO compared to the M4-02 thread on model? Perceived louder? Is the HALO OK to use indoors without hearing protection? Blow back differences between the two? Thanks Mike ***Mike, the HALO is just a bit quieter than the M402, naturally, as the M402 is significantly smaller in size. It's not a huge difference to the human ear, I'd say it's generally more observed as a tonal event. I had a group of federal agents out shooting comparing the two, and we really all ended up sounding like stereo critics, with comments like: "That one has an oakier, cardboard-like let off, versus that ones tinnier timbre and pitch...". When comparing the two, no one was going, "Wow, that's loud and that's quiet". But there is understandably a difference between the two. Blowback, I'd have to check our cyclic rate measurements - we have done a number of tests against competing suppressor brands and the G5 consistently has a lower cyclic rate on the 10.4" HK416s than most competitors, but I don't recall off the top of my head what the difference is as compared to the M402. M402s have been independently tested (there was this article in Guns & Weapons For Law Enforcement a couple years ago on the M402) where Alan Paulson metered it using military standard testing protocol and mics/meter (at muzzle location, not "at the ear" measurements), with results ranging from 30 to 34 db reduction (34 is with EBR subsonic, 30 was metered with Black Hills standard ammo). Those are his published independent results, but I'd always make the point that comparing printed/claimed dB numbers is fruitless unless they are all captured sequentially within a very short time-window, on same exact weapon, same lot/brand ammo, same meter, same shooting position, and - importantly - the results are proven repeatable. I personally don't give much credence to any results I haven't seen repeated more than a couple times. Dr. Dater and I have metered suppressors together where sometimes you'll have a fluke measurement result where a suppressor design that we KNOW performs consistently worse or better, all of a sudden has a spike in an opposite direction. Why? Could be anything, but that's just my personal opinion on the subject: One properly-taken measurement from a trusted source is certainly a good snapshot, but perhaps not the whole picture. "YMMV" always applies... With that precursory explanation out of the way, generally the HALO is a dB or so quieter, and the G5 a dB or two quieter than that. I think Paulson's numbers are higher than what we usually capture here in the Mountain states - that could relate to humidity or other atmospheric conditions, ammo, gun, meter, position, etc., but again - hopefully gives an independent academic's snapshot of the results of one test to be able to at least have some number in mind to base from. Regards, Kel GEMTECH TEAM GUY ARFCOM INDUSTRY DISCLOSURE: Geez. Haven't I disclaimed enough above already? 
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We do not post reduction figures for a number of reasons. Rather than reduction, the more important number is the absolute sound pressure level simply because that is what is related to hearing damage. For a specific SPL, the reduction will vary depending on what the non-suppressed level is. Some flash hiders have a non-suppressed SPL greater than others. For example, our measurements show the Blackout flash hider to be 2 dB louder than the birdcage, although the suppressed levels will be pretty much the same. Actual muzzle brakes will be even worse non-suppressed to the side (which is where the measurements are usually taken). Additionally, non-suppressed levels vary with barrel length, ammunition, action type (bolt, DI, piston, etc.), and measuring location. MIL-STD-1474D has several “standard” locations.
The location used by most is specified as the “reference” location of 1 meter to the left of the muzzle, 1.6 meters above grass, 90 degrees to the bore axis at the level of the muzzle. Measurements at the shooter’s ear are also specified, but when done in the field, almost never are the exact specified conditions reproduced. Most manufacturers and independent testers use the so-called reference location for suppressor comparison. Further, there is a definite day-to-day variation in measured sound levels as well as a variation in locale (desert vs. humid climates) and with temperature. I think some of this variation may be due to climate induced changes in the acoustic impedance of the air. There is a variation within a given string, which is why most folks do a 10 round average. There are people who will advertise the single best shot culled from a number of strings on a variety of measuring sessions. There are those who will use sound meters that give erroneous results because they do not meet the required specifications in MIL-STD-1474D. There are even those who fabricate SPL performance based on subjective comparisons. When a suppressed weapon is fired indoors, it is subjectively a lot louder than when shot in a grassy meadow. However, there is really little difference to the meter as to the highest single peak (the SPL that the meter measures). The reason that it is perceived as louder is because the echoes extend the duration of the peak. What is important is the issue of hearing damage. According to MIL-STD-1474D and OSHA, for short duration peak impulse noise, hearing protection must be worn if the SPL is over 140 dB. There is a little more to the issue of cumulative exposure to lower levels that would take too long to discuss here. Further, my experience in measurement has been that at the shooter’s ear, the SPL is generally 2-5 dB lower than at the reference location. Since you asked specifically about our HALO and M4-02 suppressors, they are classified as hearing safe and all are below 140 dB absolute SPL at the reference location. On the most recent tests we performed (September 2008) using the Colt M4 carbine and Israeli M855 ball ammunition, the current HALO is 2 dB louder than our G5 and 1 dB quieter than our M4-02. It is in the ballpark with our competition that we measured at the same time. The M4-02 is a slightly smaller volume suppressor than the others. Please note that on a piston upper, sound pressure levels will be anywhere from 4-8 dB louder than on the DI system, even for the same barrel length, and may not be hearing safe. I hope I have answered your questions. |
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Doc Dater
Thanks for your reply. It looks like the HALO will be the winner. I think the ultimate reason is not sound reduction but customer service. (While I was interested in the performance comparison between the thread mount and the FH mount.) Like any consumer I have been doing a little research balancing performance, cost, and customer service. GEMTECH is the clear winner. Thanks |
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Quoted:
And since you both made an appearance, what thickness should I have my smith turn my SPR bull barrel to so that the collar can be attached behind my A2? Thanks This would be my guess Quoted:
Of course - there's even been a couple of posters on these fora that have made heavy barrel ARs accept HALO suppressors by turning the heavy barrel down to 22mm for the correct length and then a reduced diameter behind to mimic the rear of the flash hider. But any brake made to the proper dimensions with an eye on tolerances and parallel to the boreline would work, all common sense applies... Kel GEMTECH TEAM GUY |
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Quoted:
Dr. Dater or Kel, By any chance, do you have figures for overall length added to weapon (not length past muzzle) for the M4-02? You have the G5 listed as 5.5" but nothing for the M4-02. Thank you, and happy New Year! Justin It is just under 5" as I recall. On the earlier question about configuring a bull barrel for the HALO, the OD of the barrel for the last 1.75" to 2" should be 0.862. Behind this should be about 3/16" length that is turned to 0.735 inches for the closer. Of course, all barrel turning should be concentric to the bore with the easiest and most accurate method of doing this is to turn the barrel between centers. |
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