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Thread: Futureweapons Open bolt M4

  1. #21
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    Quote Originally Posted by decodeddiesel View Post
    . . . an open bolt WILL NOT prevent a cook-off, at least not in the M249. I have no doubt it greatly increases the number of rounds which can be fired from the weapon prior to as cook-off. I have personally seen an M249 cook-off and run away, needless to say it was ugly.
    While no design can prevent a cook-off, open bolt (feeding on firing sequence) reduces the probability of cook-off to pretty much zero. The handguard would literally melt off of the weapon before a round not in the chamber would fire.

    Your experience was not a cook-off. If a round had cooked off, the series of events you describe could not have happened.

    -The gun would not cycle after the shot. Even if a round is in the chamber, with the bolt to the rear the piston is not close enough to the gas block to be pushed by the gasses diverted from the barrel to cycle.
    -The cooked off round would still be in the feed-tray, and immediately set the conditions for a stoppage or blow the belt out of the weapon. The feed-tray and feed tray cover would be damaged and the feed pawls would probably be missing.
    -The bullet and case would probably still be in the feed-tray, but the bullet would probably cause damage to the feed-tray cover mount.
    -The weapon would not continue to fire (even assuming that there was a round in the chamber, and the bolt was forward) as no one is pulling the trigger, unless you have a worn sear or sear notch.

    Most likely cause of your experience-

    1- Inexperienced/incompetant shooter pulls trigger and eases bolt home by hand, unintentionally feeding a round into the chamber, and leaves bullet in chamber long enough to cook-off. Bad sear engagement allows weapon to continue firing.

    2- Bolt to rear, not on "safe". Weapon sits (why it's loaded I have no idea) and heats to the point where the already bad sear/sear notch slips and fires, allowing the gun to run away.
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

  2. #22
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    F2F the circumstances were:

    We were nearing the end of the FY and the trip was a "familiarization fire" on the M249. However the actual motive was to fire 20,000 rounds through 6 weapons in a single afternoon so as to burn off all of our allocated ammo. I was the RSNCO (Range Safety NCO) and personally announced a cease fire 20 minutes prior to the incident as I viewed the conditions as extremely unsafe. I was over-ridden by my Battalion Commander (new, moronic, sent to us from the school house) and we were ordered to resume range operations. We literally had to link 200 rnd belt after 200 rnd belt because the covers could not be opened as it was too hot. The triggers on the weapons were so hot you could not hold them long enough for a 7 rnd burst without gloves. After we were ordered to keep firing I personally told them they would need to find a new RSNCO and relinquished all responsibility for anything that may happen. The weapons were clearly over-heated and it was getting miserable to fire. The RSO and new RSNCO had to remove the hand guards on all the weapons as they were beginning to melt and smoke. When the incident ocured there was an E4 on the trigger (Iraq combat vet who personally fired the weapon at enemy combatants), VERY experienced with the weapon system...

    He was engaging a target at 100-200 meter with a 9+ round burst...the target went down and he released the trigger. After no more than a 2 second pause the weapon made a LOUD poof noise and sprayed brass fragments, then went run-away for approx 15 rounds before the weapon jammed. This sent the E4 to the TMC with shrapnel in his face and hands and got the range closed down.

    Upon inspection it appeared that the out of battery cook-off had caused the fire control mechanism to fall loose the the bolt carrier group to run away. The weapon was condemned following the incident. I admit I did not have a chance to inspect the weapon as well as I would have liked, and my only formal training is as a certified unit level armorer, however this is how it looked to me.

    Obviously the weapon or weapon design cannot be faulted for this failure and malfunction, however it did occur.

  3. #23
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    Quote Originally Posted by decodeddiesel View Post
    20,000 rounds through 6 weapons in a single afternoon

    I was the RSNCO (Range Safety NCO) and personally announced a cease fire 20 minutes prior to the incident as I viewed the conditions as extremely unsafe.

    I was over-ridden by my Battalion Commander (new, moronic, sent to us from the school house) and we were ordered to resume range operations.

    the covers could not be opened as it was too hot.

    The triggers on the weapons were so hot you could not hold them long enough for a 7 rnd burst without gloves.

    relinquished all responsibility for anything that may happen.

    The weapons were clearly over-heated and it was getting miserable to fire.

    The RSO and new RSNCO had to remove the hand guards on all the weapons as they were beginning to melt and smoke.

    After no more than a 2 second pause the weapon made a LOUD poof noise and sprayed brass fragments, then went run-away for approx 15 rounds before the weapon jammed.

    the out of battery cook-off had caused the fire control mechanism to fall loose the the bolt carrier group to run away.
    Wow.

    Well, you pretty much explain exactly how to cause a cook-off in an open-bolt weapon.

    Thanks for taking the time to explain the circumstances. You were obviously correct in your determination of the situation as unsafe.

    I have investicated numerous reports of "cook-offs" with M249/M240, but all came down to user error or mechanical failure, and most others are second-hand accounts that ultimately prove unsubstantiative. I apologise for dismissing your cook-off out of hand, as all accounts came to those two reasons.
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

  4. #24
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    Quote Originally Posted by Failure2Stop View Post
    The IAR is a purpose-driven requirement with the idea being increased accuracy/precision and usability for a platform intended to increase the flexability and effectiveness of the fireteam/squad. It is not a replacement for the SAW, as the SAW is a great LMG, but a poor automatic rifle.

    There is no formal qualification requirement or plausable solution for sufficient training to correctly employ the M249, whereas the Marines have an excellent M16/M4 oriented training program. Building off the success of the training program by matching ergonomics and user-level skills of the current weapons system to the IAR makes sense.

    Regardless of the training issues, the SAW is cumbersome and a hinderance to most operations for several reasons:

    -Though the M249 utilizes standard NATO 5.56, it requires belted ammo for reliable function. Some magaine designs and follower upgrades reduce the magazine-feed problems that plagued SAWs for a long time, but cannot address the basic issues related to sub-optimal feeding sources. Since the primary feed method is by belt, the Squad/Team does not truly have ammunition interchangability. The belted ammo frequently gets snagged on vegetation, and tends to pick up foreign matter, causing stoppages that are usually not correctable by immediate action.

    -The SAW is usually carried in Condition 3, as hard impact has caused many to AD (though the argument that those are old/worn SAWs is vaild). This reduces the reaction time for the most critical weapon in the team in the event of an actual direct-fire contact.

    -Corrective action on the SAW takes far longer than an AR platform. As the SAW is the base of fire for team movement this is unacceptable. The SAW is more sensitive to maintenence and debris than the AR platform, often failing when needed most. Immediate action on the SAW rarely eliminates the stoppage cause, frequently requiring the user to go into remedial action, which takes quite some time, is difficult to accomplish from an actual fighting position, and is very difficult without visual focus on the operating parts.

    -Mounting optics on the SAW is usually accomplished by attaching the optic to a 1913 rail on the feed-tray cover. The feed-tray cover is by no means a stable enough platform for anything approaching consistent shot placement. Further, the stocks on the M249 and Para-SAW are designed to align the shooter's eye with the low-mounted iron sights. Optics sit much higher, requiring the user to raise the head to a point that cheek-position is no longer solidly on the back of the buttstock hand, reducing the ability to control the burst cone of fire.

    -The belted ammunition is noisy in drums. The patrol pouches are a bit better, but the rounds still clank against each other during movement, and are far noisier than standard M16 magazines. The drums also collect a lot of crap, especially during beach/water operations (this does also effect M16 magazines, but as they are ususally stored rounds-down, most of the crap drains right out) which is a little bit of a problem with an amphibious force.

    -Controlled single-shots, while possible, are not intuitive to the bulk of users, and usually result in poor trigger-control for experienced shooters. Add to that the limitation of the operating system itself; there is a long delay between sear release and first shot, as well as a noticeable weight shift as the operating parts move forward.

    -The weapon is only effective in bursts from the prone or a mounted position, even at close range.

    -Conducting urban operations and CQB with a 20" M16A4 sucks. It is far worse with an M249. Add to this the utter uselessness of the SAW when shoulder-fired and you see very quickly why on most operations the SAWs are pulled from the assault force to act as the cordon or fire support. Once done, the strength of the original fireteam is reduced by 1/4, and high-volume fire fire from inside the objective/objective area is virtually eliminated.

    -As the M249 is truly a LMG, it requires 2 men to effectively employ the weapon, just as with an M240G/B.

    -Firing three to eight round bursts (different tests), the SAW has no greater probability of a single strike to a target as an M16A4 or M4 at distances out to 600 meters, with three to eight times the ammuniton consumption. Think of it this way- 8 round burst per target (highest chance of single strike per burst), 200 rounds per belt. That's 25 targets, assuming that the first burst strikes the target at least once.

    -The SAW is no more caipable of intermediate barrier penetration than the M16/M4, except with concentrated fire to a specific point.

    I could keep going on, but will stop here to prevent myself from a full dissertation on the issue.

    The M249 will still be retained by the unit for use on vehicles or with the element(s) tasked with supporting the assault or as a base of fire. A 13 man squad with 6 M249s, each with a dedicated A-Gunner would be a nice thing to have for any assault. The M249 squad can maneuver on the objective under the cover of heavier supporting arms, and provide stand-off fire for the final assaulting elements from realistic engagement distances.

    The IAR Concept is a weapon that essentially feels and works like a standard service rifle, with the same sighting capabilities, and the same single-shot precision. But the IAR is able to deliver a heavy volume of fire if needed at distances typical to small arms engagements (most at under 200 meters, with the majority of them at under 75 meters), from positions realistically usable at those distances (to include the standing), and is able to employ the sighting and identification technology of the service rifle. A closed bolt intial operation is preferable for precision shots, and the ability to switch over to an open-bolt operation for suppressive fire prevents cook-offs. The objective requirement was for a closed bolt weapon, but leeway was allowed to see what industry would deliver with current technology.

    A quick-change barrel is not needed as the weapon is not intended to be employed as a continuous high volume delivery system, but as a rifle with enhanced ability to handle high-volume fire in conditions of need, to support the team/squad's advance on, and occupation of, the objective.

    The LWRC is not "THE" IAR, it is one of the competitors, though a good one. There is no requirement that the IAR be an AR derivative, LWRC just went that way with their notably non-Stoner operating system. There are non-AR based platform IAR competitors as well, some of which are quite innovative and effective. FWIW- The Ultimax is not a top performer.

    Apologies for the lengthy post. I just wanted to clarify the purpose behind the concept, as there was mention of it several times. If this would be better placed as it's own topic, I will delete and move.
    F2S is correct on all point. The IAR program is not to replace the SAW across the board, only at the four man fire team level. Remember we are talking about branch of our armed forces which trains all their troops as riflemen. The IAR we developed closely mirrors the requirements set forth by the USMC. FN, GD and LWRC where selected during phase two to provide the USMC samples for initial testing. In the next phase the companies whom provided valid proposals in phase one will be allowed to submit. I believe some of these companies are HK, Colt and Knights. Competition will be tough, but we are in good company with the above listed companies.

    Jesse
    LWRC

  5. #25
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    Quote Originally Posted by Failure2Stop View Post
    Wow.

    Well, you pretty much explain exactly how to cause a cook-off in an open-bolt weapon.

    Thanks for taking the time to explain the circumstances. You were obviously correct in your determination of the situation as unsafe.

    I have investicated numerous reports of "cook-offs" with M249/M240, but all came down to user error or mechanical failure, and most others are second-hand accounts that ultimately prove unsubstantiative. I apologise for dismissing your cook-off out of hand, as all accounts came to those two reasons.

    No problem, I realize it was a freak ocurance and even I was stunned when it happened.

    I have seen many 249/240s malfunction, and as you stated most all came down to the reasons you have stated.

    New/Inexperienced (I have seen a everything from a E1 to a SSG pull this one off) operator...

    "Clears" the weapon by easing the bolt forward with a belt in the feed tray. This results in anything from a single round AD to a multiple round run-away.

    Slams the cover down with a belt in the tray and the bolt to the rear... (I once saw an M240 Co-ax on an M1A1 tank do this for 800 rounds!! The new gunner panicked and did not know to "break the belt")

    Older weapon (especially M249) is loaded with the bolt to the rear and is slammed down onto a hard surface.

    This is the scary stuff with open bolt weapons.

  6. #26
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    Quote Originally Posted by Failure2Stop View Post
    The IAR is a purpose-driven requirement with the idea being increased accuracy/precision and usability for a platform intended to increase the flexability and effectiveness of the fireteam/squad. It is not a replacement for the SAW, as the SAW is a great LMG, but a poor automatic rifle.

    There is no formal qualification requirement or plausable solution for sufficient training to correctly employ the M249, whereas the Marines have an excellent M16/M4 oriented training program. Building off the success of the training program by matching ergonomics and user-level skills of the current weapons system to the IAR makes sense.

    Regardless of the training issues, the SAW is cumbersome and a hinderance to most operations for several reasons:

    -Though the M249 utilizes standard NATO 5.56, it requires belted ammo for reliable function. Some magaine designs and follower upgrades reduce the magazine-feed problems that plagued SAWs for a long time, but cannot address the basic issues related to sub-optimal feeding sources. Since the primary feed method is by belt, the Squad/Team does not truly have ammunition interchangability. The belted ammo frequently gets snagged on vegetation, and tends to pick up foreign matter, causing stoppages that are usually not correctable by immediate action.

    -The SAW is usually carried in Condition 3, as hard impact has caused many to AD (though the argument that those are old/worn SAWs is vaild). This reduces the reaction time for the most critical weapon in the team in the event of an actual direct-fire contact.

    -Corrective action on the SAW takes far longer than an AR platform. As the SAW is the base of fire for team movement this is unacceptable. The SAW is more sensitive to maintenence and debris than the AR platform, often failing when needed most. Immediate action on the SAW rarely eliminates the stoppage cause, frequently requiring the user to go into remedial action, which takes quite some time, is difficult to accomplish from an actual fighting position, and is very difficult without visual focus on the operating parts.

    -Mounting optics on the SAW is usually accomplished by attaching the optic to a 1913 rail on the feed-tray cover. The feed-tray cover is by no means a stable enough platform for anything approaching consistent shot placement. Further, the stocks on the M249 and Para-SAW are designed to align the shooter's eye with the low-mounted iron sights. Optics sit much higher, requiring the user to raise the head to a point that cheek-position is no longer solidly on the back of the buttstock hand, reducing the ability to control the burst cone of fire.

    -The belted ammunition is noisy in drums. The patrol pouches are a bit better, but the rounds still clank against each other during movement, and are far noisier than standard M16 magazines. The drums also collect a lot of crap, especially during beach/water operations (this does also effect M16 magazines, but as they are ususally stored rounds-down, most of the crap drains right out) which is a little bit of a problem with an amphibious force.

    -Controlled single-shots, while possible, are not intuitive to the bulk of users, and usually result in poor trigger-control for experienced shooters. Add to that the limitation of the operating system itself; there is a long delay between sear release and first shot, as well as a noticeable weight shift as the operating parts move forward.

    -The weapon is only effective in bursts from the prone or a mounted position, even at close range.

    -Conducting urban operations and CQB with a 20" M16A4 sucks. It is far worse with an M249. Add to this the utter uselessness of the SAW when shoulder-fired and you see very quickly why on most operations the SAWs are pulled from the assault force to act as the cordon or fire support. Once done, the strength of the original fireteam is reduced by 1/4, and high-volume fire fire from inside the objective/objective area is virtually eliminated.

    -As the M249 is truly a LMG, it requires 2 men to effectively employ the weapon, just as with an M240G/B.

    -Firing three to eight round bursts (different tests), the SAW has no greater probability of a single strike to a target as an M16A4 or M4 at distances out to 600 meters, with three to eight times the ammuniton consumption. Think of it this way- 8 round burst per target (highest chance of single strike per burst), 200 rounds per belt. That's 25 targets, assuming that the first burst strikes the target at least once.

    -The SAW is no more caipable of intermediate barrier penetration than the M16/M4, except with concentrated fire to a specific point.

    I could keep going on, but will stop here to prevent myself from a full dissertation on the issue.

    The M249 will still be retained by the unit for use on vehicles or with the element(s) tasked with supporting the assault or as a base of fire. A 13 man squad with 6 M249s, each with a dedicated A-Gunner would be a nice thing to have for any assault. The M249 squad can maneuver on the objective under the cover of heavier supporting arms, and provide stand-off fire for the final assaulting elements from realistic engagement distances.

    The IAR Concept is a weapon that essentially feels and works like a standard service rifle, with the same sighting capabilities, and the same single-shot precision. But the IAR is able to deliver a heavy volume of fire if needed at distances typical to small arms engagements (most at under 200 meters, with the majority of them at under 75 meters), from positions realistically usable at those distances (to include the standing), and is able to employ the sighting and identification technology of the service rifle. A closed bolt intial operation is preferable for precision shots, and the ability to switch over to an open-bolt operation for suppressive fire prevents cook-offs. The objective requirement was for a closed bolt weapon, but leeway was allowed to see what industry would deliver with current technology.

    A quick-change barrel is not needed as the weapon is not intended to be employed as a continuous high volume delivery system, but as a rifle with enhanced ability to handle high-volume fire in conditions of need, to support the team/squad's advance on, and occupation of, the objective.

    The LWRC is not "THE" IAR, it is one of the competitors, though a good one. There is no requirement that the IAR be an AR derivative, LWRC just went that way with their notably non-Stoner operating system. There are non-AR based platform IAR competitors as well, some of which are quite innovative and effective. FWIW- The Ultimax is not a top performer.

    Apologies for the lengthy post. I just wanted to clarify the purpose behind the concept, as there was mention of it several times. If this would be better placed as it's own topic, I will delete and move.
    This man speaks wisdom. Listen all ye to him.

    (F2S, I'll bill ya later).
    Last edited by The Archangel; 12-23-08 at 14:54.
    "I stayed at a Holiday Inn Express last night..."

  7. #27
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    Wow back from the dead.

  8. #28
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    Quote Originally Posted by Tspeis View Post
    I'm almost certain FN submitted a modified variation of the SCAR for the IAR trials.


    Tspeis


    And the Colt:

    "The secret to happiness is freedom, and the secret to freedom is courage." - Thucydides, c. 410 BC

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