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Posted: 7/24/2004 6:27:03 AM EDT
| What issues has the military had with the KAC RAS? |
| I just remember reading here on the boards about various issues such as torquing barrels and nuts due to the vert grip as well as lower rails coming loose. I never really followed most of it so I'm just wondering what some of those issues were if any of them were legit. |
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The only problem that I'm aware of is that having a lot of weight hanging on the barrel (the RAS isn't FF) will cause some barrel sag and can change the bolt/barrel interface angle enough to add additional stress to the bolt. Thus, an increase in bolts cracking. Also, uppers have been observed with oblong barrel holes due to this. That was the big push for developing FF versions of these rails. -Troy |
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I discussed this matter with personnel at Diemaco, Crane and others. The issue is not the RAS but the associated kit, and even then there is no common consensus on the effect. I have summarized point told to me below. Suppressors are in the opinion of some the most abusive addition (although a necessary tool) the higher cyclic and increased heat are detrimental to the weapon lifespan. The Vertical grip is the next in the order of sequence - as some troops exert a great deal of downward pressure on these grips which is correspondingly transfered onto the handguard and from there the barrel and barrel extension. IN THEORY The heat generated, and the effect of the heat onto the aluminum upper receiver's threaded portion for the barrel nut (right near the chamber) -- Pressure onto the barrel/handguard is transfered onto this area. IF this is repeated the force and the heat can cause warping of this area. The bolt can come out of alignment with the barrel extension which will cause addtional stresses onto the upper and the bolt - reducing reliability and life of the bolt. |
Thanks, Kevin. Could the same be true for a FF system? |
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The FF will reduce the weight on the barrel/barrel extension. Some are designed as heatsinks to draw heat away from the barrel nut/chamber area. With the FF the majority of the SOPMOD kit weight will be removed from the barrel, as well KAC has their E3 bolt upgrade and LMT has theirs as additional reliability and lifespan multipliers. Suppressors - heck operator survivability is much more of an issue with me than weapon lifespan. If they can't afford to buy a new upper now and then they don't have a proper value on me... |
 You saw where I said THEORY  IMHO while this will happen - it happens at the abuse point of the weapon. I don't see this happening in everyday usage - and if units are trg this way something is wrong. I am a supporter of FF'ing but I don't think the RAS or RIS are the problem some think. If a unit/force was to adopt a new MWS I would say URX - but is it worth replacing ones already in the sytem??? |
Curious. Considering that I'm only an "Armchair Commando," why would they be exerting significant downward force on the vertical foregrip? Seems more like they would be either exerting neutral, or maybe to suport the front heavy rifles, upwards force. Don't understand pulling down on a foregrip.  Lonny |
To counter the upward travel of the muzzle under sustained fire... |
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The biggest problems I have encountered with the non-feefloating system are: The rivets for the heatshields coming loose and causing them to rattle (25-50% of them do this that I have found) So most of the guys I work for just take them out. The screw for the newer model that holds the rear clamp in position is too long on about 25% of the ones that I install-It binds the gas tube so bad on some that the rifle will not work. Or, one of my personal favorites: Is when it just binds the gas tube enough that when the gun heats up it binds the weapon up and it does not work when it gets hot (60-90 rounds), hell of a time to find out that the screw f's up your gun. It also has this effect from time to time that the barrel shoots loose but is not detected until it (the screw) is removed, the side product: you get a wandering zero and an apparently tight barrel (that one stumped me for a day or two). Quite a few guys I know don't use the screw or they take them out. I also get a few complaints about them breaking, especially the lower guard. Other than those probs. it overall is not a bad idea and fits a niche. |
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VERY INTERESTING. THE M4/M5 RAS "CLAW SCREW", WE'LL CALL IT, IS AN ISSUE OF WHICH I WAS UNAWARE. IT DOES HAVE A SPECIFIC TORQUE VALUE, AND THE KAC M4/M5 RAS INSTALLATION INSTRUCTIONS COME WITH A CAUTION TO NOT OVERTIGHTEN. NOW I THINK I KNOW WHY. THANKS FOR SHARING. WES |
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The Rear M4/M5 RAS Screw being too long is also news to me. With almost 100,000+ of our (KAC) RAS's out their in service, I have never heard of this one. My guess is that these are instances where an after market Hardware Store screw is being used as a substitute. My opinio on this as a possibility stems from me daily providing forward deployed Armorers the Army's Part Numbe r& NSN so they can order replacement screws. This information was published in the Army's TM several years ago as RAS were being fielded, but many, many units don't have the new TM changes or know how to get them. I have seen several "After Action Reports" from the Army's Rock Island Arsenal Equipment Specialists that inspect units about to deploy to Iraq, who are there now, or have just returned and are re-fitting. TRhe screw being "missing" is very common as the individual Soldiers feel an imperative to remove it frequently to more easily clean their weapon. Also sometimes missing is the whole rear clamp assembly. This is common in some Ranger Units originally issued the RIS way back when USSOCOM was sending them out to select units. The troops got used to removing the RIS just like issue plastic handguards, but when the RAS's replaced them, the rear screw/clamp made this unathorized level of field-stripping too difficult, so ... First off, the issue screw is so short, I don't think its physical possible for it to go in far enough to touch the gas tube...unless, the screw has been over-torqued and has broken thru its "counter-bore seat" in the upper RAS. But if this is true, the upper needs to be replace anyway. Rivets/heat shild issues (I think) have been finally solved by reversing the rivet head to the inside surface, and peening the end on the outside of the lower where the material thickness is greater. You know you have the latest is the rivets are peened that way, because the Army only recently (this year) approved our recommended change. On the Urban Myth relating to bending barrels, sheared bolt lugs, lossening barrel nuts, etc., I SAY NUTS! I have posted the results of our testing trying to dublicate this as far back as two years ago...sso here is the short version. (1) think about these heavy match barrels out there...if weight hanging out into space could cause the UR to warp, and result in enough misalignment to shear a bolt lug, I think we'd heard about it long, long ago, and I have never seen or heard of such an event. (2) putting excessive pressure on the vertical grip does not bend the barrel and affewct accuracy or point of impact, its the change in barrel harmonics from the lower rail pushing on the forend cap that does it. Think about the linear arrangement of the upper, lower, and then the forward pistol grip at a 90 gegree angle to that...you just can't "bend the barrel" because the lines of force you set in motion by the forward or backward pressure go staight back and forth thru the lower in a straigh line. You might be bending the lower ever so slightly, but if the pistol grip is located somewhere in the mid section, your leverage advantage is significantly deminished, and your lines of force (pulling rearwards) bear on the forend cap not the barrel's mid-section. Another way to look at this is to ask, if the barrel is bending due to pressure on the fore grip, where is the lever's focrum? Now a position shooter with a leather match sling attached up by the front sight, and his supoprt hand under the forend with that artms elbow stuck in the dirt can bend the barrel temporaily and cause his shot group to move or disperse, but his elbow/fore arm is acting as a fucrum for the energy to "follow the lines of force'' backwards from the sling swivel, through the barrel to where his fore arm is acting as a focrum, and down his arm into the ground. (3) As Kevin observes above, the now more frequent and sustained use of sound suppressors is what is breaking bolts, etc., that are not yet re-engineered and re-designed to survive very long in the "higher that designed-to threshold" cyclic rates that the suppressors impose. That is why we designed our E3 Bolt. I.e, improved design bolt lugs, extractor, smaller diameter cam pin, etc. (4) Loose barrel nuts is a problem that started showing up in the mid-70's as Viet-Nam era rifles were reaching the 6,000+ round point. Problem still exists, like 3 summers ago when the Marines at Camp Lejune were testing a very large number of new M4's vs M16A2'/A4's. The M4's in their testing sffered a noteworthy numbe of loose barrels (straight from the factory). (5) Any Marines out there reading this, please pass this along: take all those extra handguard panels off the top rail of your M16A4's. I know your new rifles are being issued to you like this, but clear the top rail before you go to zero the sights on the removable carrying handle. The barrel will cool much better without them, and your rifle's top rail will be ready to accept accessories without the need to remove the carrying handle first to slide off the top rail panels. |
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Cold blue I have filed numerous QDR's on those problems to RIA and also talked to some of the engineers about these shortcomings when they come up to Bragg to participate in various tests. The problem with the screws is the same on new ones out of the box when I install them I check for binding I also check on replacement one: also same probs. I have only seen about 2 after market screws. As for loose barrel nuts yep, Colt is famous for that on the M4A1s I service, the barrels are not installed properly at colt on about 15%-20% of M4A1s had to be tightened properly to spec and in 2 yrs I have not had one that was tightened properly shoot loose. |
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OK, here is the history. Back in 1999, we used a slightly longer rear clamp srew that was later found to be too long on some rifles (sorry, but forgot about this last night when I posted). This was also coincidental with the gas tube clearance issue I referenced above. Our Contact teams were to several Army bases to retro-fit with new spacers and shorter screws, but not every RAS then in Army hands was modified. I was told Rock Island issued change-over info, new part numbers, etc. to the field. The old/long screw can be identified by its pacth of Red Nylock. The newer (from 1999-2000) one is shorter and has a Blue Nylock patch. I have one here in my hand right now, and even withour a RAS inbetween, the screw can be turned all the way flush with the clamp, and the end does not stick out to where the gas tube would pass. |
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In my many years of messing with Class 3 I have disassembled many Colt M16s of various models and vintages. On a pretty fair number of them, and I am talking well used M16s, I have found a lot of them with the barrel nuts loose to the point that the gas tube was holding them in place. Other took almost no pressure on the barrel nut to loosen it. Denny |
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