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Posted: 4/22/2010 4:58:13 PM EDT
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Who here uses one? How does it improve extraction. And most importantly where exactly does it go.
Thanks for your advice and help. |
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Don't use it unless you have extraction issues. It chews up brass pretty good. You can try it out but you'll see it makes no difference on a healthy rifle other than tiny peices of brass in your reciever.
P.S. Billy Jack was my favorite movie since I was 8 years old 
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Does anybody know what size o-ring it is?
Or the mil dash #? You can buy a o-rings for chemical resistance from McMaster-Carr in PTFE, Fluorosilicone, Viton. I have used Fluorosilicone in a mil / aero application before with excellent results. Great temp. range and durometer of A 70. I think it should work well for this. |
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I use them on all my four AR, two carbine, one midlength, and one rifle gas systems, I'm running either the BCM (from Bravo Co. & Global Tactical Supply) and Crane O-ring (from ADCO), you could get equivalent O-rings like the other member posted but look at the thread archives for the actual part number and size.
On my midlength and rifle gas systems it increased the extraction force and made my brass lands on a small area slightly further away than when not using the O-rings. With my carbine gas system, I'm using the O-ring with an extra power CS extractor spring from the BCM extractor upgrade kit. When I first installed both the O-ring and extra power spring I felt it was too much so I didn't install the O-ring at first and just break-in the spring for around 600 rounds, then after that I installed the O-ring without problems, no unusual signs of problems on all my spent brass from all my AR. I'm running mine with three Colt and one LMT BCG all with auto bolt carriers. |
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Quoted:
The o ring came with my Bravo Co. BCG. Bravo Co. includes it pretty much to make you happy that you got something extra with your BCG, it is a band aid more than anything and not a permanent solution for an extraction problem. These are not my words, this is what Paul told me when I sent my BCG back for an extraction issue. |
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I personally have seen no use for the o-ring in my carbines.I only use "known quality" extractor springs and inserts.
That said the only carbines I have is LMT and BCM which have proper gas port sizes and are as a result properly gased. As a note if you have a BCM BCG then you also have the robust BCM extractor spring in place which is heads above the rest in extractor tension and durability...thus the o-ring is not needed. In my midlength (Armalite and BCM uppers) I have yet see see a need for the o-ring.In a rifle length upper(namely Armalite 20" SPR's) I personally had issues with the bolt failing to go into battery due to the o-ring giving excessive extractor tension straight out of the box,which closely resembled bolt bounce in my opinion.Removed the funky little oring and all was well. Why Armalite see's a need to install the o-ring on midlength and rifle uppers I have no idea as those were not the target application. The o-ring from my understanding is only needed in some FA and SBR applications. |
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Quoted:
Don't use it unless you have extraction issues. It chews up brass pretty good. You can try it out but you'll see it makes no difference on a healthy rifle other than tiny peices of brass in your reciever. P.S. Billy Jack was my favorite movie since I was 8 years old +1 took mine out and its a lot better. If it aint broke........ |
| Be advised that inexpensive plumbing O rings do NOT hold up. I got some #60s at Home Depot, slipped one into my bolt and felt smug. Later, I tore down the bolt to clean it thoroughly and the cheap ring had squished-no spring left in it at all. Crane O rings are made from Viton, a flurocarbon material. Cheaper ones are made from nitrile or silicone, neither of which has the requisite characteristics. Good for an emergency, sure, but if you really NEED a Crane O ring, get a Crane O ring. |
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All of my rifles except one have BCM BCG's and they extract just fine so I do not install the o-ring. The other one has a YM NM BCG which I replaced the extractor spring and insert with the BCM HD unit and black insert.
The only time I've used an o-ring is for friends' RRA and Stag rifles running stock BCG's with the weaker std extractor spring and blue insert. note: RRA's have a black insert but it is the same density as the blue ones, nothing like the real black inserts. |
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There has been extensive discussion concerning the use of Crane O rings/ Defender D-Rings on m4carbine.net Crane O rings.
What I find interesting is that the original inventors of these O-ring/Defender extractor spring helpers (Jim Sullivan and Mack Gwinn) were people with alot of AR designing skill (Sullivan worked with the AR's original designer, Eugene Stoner. Gwinn was the founder of Bushmaster). They conducted numerous tests indicating fewer extraction failures and little to no side effects. Several military and LE observations also report the same findings. I am not one to jump on the latest fad or trick of the week, but these elastomer D/ O-rings have been around for more than two decades, and have been adopted in some form or another by military, law enforcement, and major firearms manufacturers as original equipment. I do not have enough experience with them myself, and since leaving active duty, probably will never fire enough rounds to validate whether they are necessary or not. The people that do have those resources (military, LE, manufacturers) seem to have undergone a paradigm shift more and more towards mainstream use of these devices, especially on the short Carbine length gas system rifles. Extraction failures have always plagued the AR since its original introduction and this was more pronounced on the shorter weapons when they were hot and dirty. Failure to extract problems are major malfunctions that can put a rifleman out of commission for several minutes or more. Cleanliness and what I perceive was a low quality extractor spring led to many extractor problems on the original M16A1. As a military armorer, maintaining hundreds of weapons that annually fired thousands upon thousands of rounds each, I found a vast majority of the original extractor springs would "bend over" and take a permanent set looking like a leaning tower of Piza. Weapons on the range that displayed numerous extraction problems normally presented this condition and the quick-fix was to replace the spring. Quite frequently, the worst springs lost their shape so bad, they would not friction fit in the extractor and would easily fall out and get lost during cleaning. These old springs didn't last very long either, and I kept a large supply of them on hand. Around the mid '80s, a new spring came with the now familiar "blue" colored insert and were installed as a set due to a directed Army-wide modification. Like the O-ring, many people questioned whether that little blue silicon looking insert would actually hold up, especially during the heat and abuse from full auto fire; and even if it was necessary to begin with. The reality is that once the new spring and insert were installed, field and range extraction problems dropped significantly––especially during rapid and auto fire. The springs no longer bent over and took a permanent set, and extraction reliability improved. I rarely replaced a defective one and fewer of them were lost during cleaning. In the '90s, when the M16A2s were issued, those springs with inserts were standard equipment. Today, those inserts are considered proven technology and the only questions are not whether to use them , but rather which color (blue or black), and which spring 4 or 5 coil (gold or black) to use on your Carbine or Rifle length. I have never really had it explained to me in exact detail the how or why the combination of the inserts and springs work, but I have my own unvalidated ideas based on the poor leverage angle of the extractor on the spring, the perceived damping effect, and additional tension provided by the elastomer insert. What ever it is, they work. As far as the O-rings, I seem to believe that they offer an improved performance advantage. My new Noveske came with an O-ring installed and it performs flawless with the few rounds I have fired. Several weapons manufacturers install these as original equipment. Of course, others may not believe having one is necessary. I suppose, if you were to desire one, I would recommend buying and installing the spring, insert, and O-ring as a matched set from the same well-known vendor. Budget buying one from the lowest price Chinese vendor is probably not the way to go. For the OP that began this thread, I would try it both ways, and if you find it tears up your brass or impairs going into full battery, by all means don't leave it in there. The way I see it, one failure is too many––especially if you are risking life or limb on it. Just for numbers, I don't think I personally had more than 4 of these happen through my entire 20 year military career––and I was a competitive shooter shooting more than the average Joe. On the ranges, I can't remember how many I cleared for others––way over a hundred (mostly with the M16A1), I see a few people commenting about how the extractor kicks out their brass. This is not quite right. The extractor's primary job is to pull the spent case from the chamber––and that is where failure occurs––when the cartridge case lip slips out of the extractor groove and stays in the chamber. The ejector––that little round push-plunger on the bolt face––its job is to kick the brass out of the receiver. Granted, the extractor has a minimal function in ejection––but it is merely a pivot point to direct the brass out of the ejection port. The spring tension of the extractor has very little effect on the ejection process. Presently, I am not relying on my AR to save my life. But, when I did, I realized how much of an impact a failure to extract could have. It could be life threatening if you are expecting it to go bang and it doesn't. The few extraction failures I had, I could not rapidly put the weapon back in service with immediate action. If I was facing hostiles, I would not be here. The basic problem is that the extractor fails to pull the spent case out of the chamber. The bolt travels to the rear and strips a new cartridge from the magazine and attempts to jam it into the back of the spent case still in the chamber. Immediate action (S.P.O.R.T.S) –– Slap the magazine, Pull the charging handle, Observe expended case, Release charging handle, Tap forward assist, Squeeze trigger) does not work––it merely attempts to jam another cartridge into the back of the case making it stuck worse. The two methods of correcting the malfunction put the rifleman out of service. On a range, and what I would advise most to do, is to place the weapon on safe, lock the bolt to the rear, drop the magazine, remove loose cartridges, and insert a cleaning rod from the muzzle pushing the case out of the chamber (alot less wear and tear on the weapon). Another method (more combat expedient) is to put the weapon on safe, drop the magazine, remove loose cartridges, then attempt to drop the bolt on the cartridge case still in the chamber. Slamming the bolt on the case can have some ill effects on the extractor since it has to try and expand out over the cartridge lip while it is locked in battery. I have repaired a few broken extractors from doing this––but I would do it in a heart beat if my survival depended on it. This method only works sometimes, as depending on the original cause for the failure to extract, sometimes the brass is chipped right where the extractor is trying to grip the rim of the case (this is made even worse by dropping the bolt onto it). Either way you correct it, the time it takes is not going to help you score a good match time, and you better have some cover on a two-way-range. If an O-ring could keep this from happening just once in the life of the rifle, it could be the "once" that saves your life. Reloaders with range guns have a different priority, and may not want the extra stress on the case edges. |
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RedZ - Thanks good info!
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– McMaster has Mil Spec. -006 Viton 50) for $4.82 (P/N 1201T16) - 75 hardness & Fluorosilicone 5) for $1.25 (P/N 8333T116) - 70 hardness Viton -006 100) for $4.88 (9464K11) - 75 hardness |
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Slightly unrelated. Where can I find a list of AR malfunctions and their remedies? By the way, I have been running my Mk18 clone sans O ring without issue. Here is a short quick Army guideArmy Malfunctions I personally like the original Military books FM 23-9 Rifle Marksmanship, and the M16A2 TM. |
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Where can I find a list of AR malfunctions and their remedies? Not a list but useful. Here is the artical that got me interested in the o-rings to start with. According to this, remove the mag failures (80%+ IIRC) and most failures are buffer spring and extractor related. |
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I reload all my fired .223 / 5.56 brass and have the o-rings in all my rifles. Just put one on the last rifle with out one this weekend. Never had a problem yet.
I usually reload them 3-4 times before discarding them in the recycle bucket. I have had 0 malfunctions to date since using them. |
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Sorry about the list, I went with what I knew, and the military study guide was the easiest/fastest thing to reference for failures and corrective actions. For more indepth, check out the military TMs, versions ending with -10 are operators manuals and contain the same info as what I referenced before. A -20 or higher will give you unit level armorers and higher repair info (higher, ie -30, -40). The reality is, there most likely are civilian versions that are more informative and easier to read––I am not familiar with them. Maybe some one else can chime in?
The article you cited seems to be accurate from my experience. Once you eliminate Magazines, Operator error, and Ammo, very few mechanical problems exist with the rifle itself. After those, fouling is the next highest frequency presenting with multiple problems of short stroking, failure to extract, failure to eject, failure to feed, etc. Keep it clean and those problems go away. Then, as the author mentioned, short stroking due to buffer spring, and ejection and extraction failures (all are fairly rare). We did not experiment with different springs or different buffers––only mil spec replacements would almost always repair, or the problem was related to something else. The M16/AR is a pretty idiot-proof weapon. However, most of the problems encountered on ranges were almost always attributed to operator error. Improper assembly––Gas ring gaps all lined up, bent gas tube, improper cleaning, etc. Before throwing parts at the weapon, check those first. I can remember several times being on ranges were we had to get rid of ammo (once it was removed from its lot# controlled case and loaded in magazines, it can't be turned back in). I fired thousands upon thousands of rounds many times. What I discovered, is that as a soldier, my basic load of ammo (6ea 30 rnd mags) was not enough to foul the weapon to a point to cause any problems––it takes thousands. When the rifle starts to slow down from fouling, you can squirt some Breakfree in it and shoot even more. I remember removing the bolt after some of these firings and visibly seeing "gold glitter" every where. The glitter being small flakes of brass that were chipped off the rounds during cycling. The entire bolt face would look gold plated, and flakes jammed in, and around the ejector, firing pin hole, and the extractor groove partially filled. It takes a while to clean, but what is learned is that I cannot carry or load fast enough the ammo required to foul a weapon to the point of malfunction in a single setting––not to mention, the weapon gets too hot to comfortably hold on to and the mirage heat from the barrel ruins any kind of sight picture. {quote]Quoted: Quoted:
Where can I find a list of AR malfunctions and their remedies? Not a list but useful. Here is the artical that got me interested in the o-rings to start with. According to this, remove the mag failures (80%+ IIRC) and most failures are buffer spring and extractor related.[/quote] |
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Does anybody know what size o-ring it is? http://www.mcmaster.com/param/images/orings/blueoring2.gif Or the mil dash #? You can buy a o-rings for chemical resistance from McMaster-Carr in PTFE, Fluorosilicone, Viton. I have used Fluorosilicone in a mil / aero application before with excellent results. Great temp. range and durometer of A 70. I think it should work well for this. #60 o-ring |
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