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Posted: 10/28/2005 9:42:42 AM EDT
[Last Edit: Tweak]
Am deployed in Iraq on PSD task
Took recently purchased M4 to range for test-firing today. Weapon is 10.5" LMT upper, mated to Bushmaster Lower(XM15-E2S). Bolt carrier/bolt, etc are all LMT. Charging handle is PRI. Weapon has had approximately 50 rounds through it before today. Weapon was spotless prior to firing, with light lube on working parts. New magazines used. Manufacturer O-Ray or C-Ray (?) Industries Inc, New Britain, CT USA. Ammunition fired 2002/2003 LC M855. The weapon fired approximately 50-60 rounds without issue, then had recurring identical double feed jams, every 4-10 rounds, which could not be fixed. Tried cleaning on-site, no fix Tried using less rounds in magazines, no fix Double feed stoppage always presented as partially extracted fired case, extractor not engaged and new round jammed into base of partially extracted case. Weapon fired and bolt cycled to rear and stoppage occurred on forward stroke. All advice urgently welcomed. This was slated to be an operational weapon and prices here are astronomical and access to armorers limited. |
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Will the bolt lock to the rear on firing only one round out of a magazine? Have you checked if the bolt carrier key is tight? If the extractor is off the base of the cartridge case, is the entire extractor intact or crud under the lip? Pull the extractor and try to compress the extractor spring by hand. It should be very stiff. There has been some discussion about bad extractor springs lately. You could try to solve with an Extractor D-Fender from Armforte or a small O-ring but it's much better to fix the problem and get the riffle running right bedore making additions. Once the gun IS right, then a D-Fender of O-ring would be appropriate. I've got one on every one of my agency's guns and they do cut down on problems. |
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Art B.
------------------------------- Character: Doing the right thing when no one is watching. |
Do the "short stroke test" to make sure that it will lock the bolt open on one round fired(last round in mag).
If it locks open reliably, then try the following: First, check the condition of the extractor and spring to be sure they are good. Then increase extractor spring pressure by whatever means is accessible to you, meaning a O-ring, stronger spring, D-Fender, insert, whatever. That should take you a long way to getting there, or cure it. If it persists, try a heavier buffer. |
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Too bad you dont have a Lowes handy, a .08 cent #60 o ring will probably cure that. The fired brass isnt going bye-bye, and its cockblocking that newly fed round. That fired brass must unass that AO. I have o rings in all my AR's. |
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Every penny profit we send abroad goes to competition for the worlds oil supply.
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Art B.
------------------------------- Character: Doing the right thing when no one is watching. |
Heavier mass slightly retards bolt-opening timing, which will allow pressures to drop slightly further before the bolt can unlock and try to extract the round.
The higher pressure present inside the case, when the bolt opening cycle begins, is what causes this difficult extraction condition in carbines. In 10.5" barrels, the dwell time is so short that the gas port must be bigger than usual to force the bolt open quickly, and when the pressure in the case is high, the case is swelled against the chamber and doesn't want to come out easily. So what happens is, the extractor with normal-power spring slips off the case rim before the extraction is completed, thus this classic jam pattern. Added extractor spring tension and possibly heavier mass in the buffer can both help to solve this issue in carbines. |
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TWL, Thanks for the info. It makes a lot of sense.
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Art B.
------------------------------- Character: Doing the right thing when no one is watching. |
Have looked at the bolt carrier key - it's on good and tight
extractor is complete, with a fractional amount of GSR/carbon fouling under the claw will try to find an o-ring somewhere. I take it the idea is simply to slip the o-ring over the extractor spring? can anyone recommend a good heavier buffer spring and HD extractor spring? my kingdom for an o-ring.... |
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The weapon should already have an H buffer in it.
Best advice since you are stuck in the suck, see if the services has any plumbing supplies somewhere to fix the water faucets (best bet in finding the Small O rings), and once installed, Dump about 6 mags back to back with the MG's upper well lubed in CLP (got to be a sand dune somewhere that needs some killing). This will allow the chamber to self-polish out threw live fire. Once completed, get the CLP/fouling out of the rifle, since the CLP is just going to be a sand/dust magnet. P.S. If you can, dump the LMT barrel and get your hands on a Colt or FN barrel instead. The chambers are looser in the sidewall dimensions on these barrel, and when shit gets adverse, a nice tight chamber that shoot really tight groups is going to be your demise after the rifle jams up on repeated mag dumps when running the weapon un-lubed for the present conditions. |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
thanks for the tips, gents
tweak - have IM'd you my mailing address. any assistance appreciated weapon has 'H' buffer installed recommended replacement extractor? don't know if I'd burn 6 mags on a sand dune. there's plenty of other things here that need killing... .will give it a shot, pardon the pun. will scrounge around in meantime for o rings. |
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COLT or FN, marked with either a C or an F underneath in front of where the extractor spring seats. Make sure it has the black extractor spring insert if you're getting it from a USGI source. O rings out today if I can, no later than tomorrow. ETA, you're not set to accept IMs so I'll post my answer here
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
an anonymous but outstanding source has also sent a pack to you, those will get there first as mine have yet to be purchased. Spread them around.
Man, bet I could make a killing setting up a mobile arms repair shop over there. |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
tweak
thanks for your help and also to anyone else who has chipped in - i'm extremely appreciative will look for another extractor and barrel, hopefully I'll be able to scrounge something up. you could make a bloody fortune if you set up a decent armoring outfit over here. I hear about a dozen requests a day for weapons fixes, parts and that's just from within the project I'm on. Mutiply that by numerous other projects and you'd be flat out, not to mention cashed up. skorp |
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skorp, I'll throw in a good one and a super duty extractor spring with the pack of O rings. |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
I'm tempermental. 5% temper, the rest is mental.
FL, USA
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Can you grab up an AK for the time being?
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"Try not to think about dying, that might make you nervous." |
tweak - thanks mate, again - extremely appreciative
cap'n p - have switched to a back-up AK. It's a love-hate relationship but the thing rarely misses a beat. Only problems I've ever experienced with that particular system has been 'quality' third-world ammo. |
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skorp,
have you been dealing with Paul at Bravo Co about this rifle? |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
bump
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
Tweak
Sorry mate for the tardy reply, have been out and about. No, I haven't been dealing with Paul at Bravo Co. I assume you're talking about Bravo Company in the US? A friend here took the rifle to see an armorer here and I don't know what his name was. In any event, there was no change after trying a new extractor. Haven't scrounged any other parts yet, so will probably have to wait for the o-rings you've sent. Am on the hunt for a 14.5" barrel also. No luck yet. Skorp |
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did he try a new spring or just the extractor? Is your bolt a standard one? LMT also makes an enhanced model.
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
Check your EJECTOR and spring to see if you have proper tension and no brass shavings stuck in the ejector hole. If you're getting proper extraction (out of the chamber) and the base of the case is free of the bolt face (but not kicking the empty overboard) your ejector spring may not be pushing the case out through the ejection port before it's getting caught on the bolt's forward thrust while stripping a new round from the magazine (especially since you say you have no extractor issues and you are running a heavy buffer). This could also lead to the inevitable empty stuck above the bolt and jamming the charging handle forward (requiring removal of the upper to pull the empty out of between the charging handle and barrel extension).
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The extractor is dropping the case |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
They tried a new spring and extractor for the same result - extactor slipping off case head and resultant serious FtEx stoppage as new round tried to chamber - straight into base of partially extracted case.
My LMT bolt is standard and appears to be chromed or stainless? (I suspect the former). I haven't used LMT previously. On that note, I'm no brand partisan. I don't give a you-know-what about different manufactuers, just so long as their equipment doesn't get me or one of my team-mates killed because it's not up to snuff and decided to stop when it shouldn't. So far, this piece of kit is not up to the task and forgiveness out here is pretty thin on the ground, war being a harsh judge of men and equipment. Frankly, a lot of people out here don't have the time or resources to remedy problems that should never occur in the first place. Get a spare part?? We're in Iraq. You want to order parts as a non-mil contractor? Good luck - you can either go through the end-user certificate your company might have (we're still waiting for magazines ordered in April) or try and battle past State Dept restrictions on weapon part sales to individuals. Fat chance. If I was in front of the LMT boss right now, we'd be having a pretty frank discussion. And that would go for any other manufacturer (and I'm sure there are plenty) who couldn't get the most important thing right, every time - reliability. Lack of it gets good people slotted. |
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If you can lay hands on another H buffer you can disassemble it, and add the heavy weight in it to your current buffer, that will bump up the weight. Commando barrels really need H3 buffers.
If you can try a rifle stock, I'm hesitant to push the extraction issue when it may be something bigger that may lead to problems later. Also have you checked the free length of the buffer spring? I'm assuming you're running a collapsible stock. |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
Running a SOPMOD collapsible
buffer spring length seems ok. It's new and still pretty stiff. I'll try out the xtra buffer weight. I don't want to fix the symptoms either. Although the 10.5" is fast out of a car, I'm more than willing to trade that off for the extra reliability inherent in a 14.5" (although that's still short). The extra muzzle velocity wouldn't hurt either, particularly on Mr Muj. |
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Skorp, I read your post quickly and did not note the 10.5-inch tube.
OK, sounds like you need the 11.5 barrel, but if you can get one the issue 14.5. Go with a rubber D-fender or O-ring for under the extractor. You have no way of knowing (or fixing) the size of your gas port. 10.5s are notorious for being picky feeders (the 11.5" Colt Commando is the shortest in-production barrel Colt produces and i have seen in general issue because of the fine balance between short and functional). Any of the heavier buffers will keep you in good stead with the 11.5 or 14.5. Good luck. |
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Sinister
Thanks mate - am definitely trying to get a longer barrel and will sort the o-ring issue also. |
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skorp, let us know how make out. I would imagine your odds of procuring an 11.5 in theater are fairly low, so I would concur with the 14.5 suggestion. And a complete Colt bolt group if you can find one as well, or FN for that matter.
LMT's product is inconsistent to say the least. What might be acceptable for the recreational shooter, who has time to wring out any bugs, is UNSAT for a guy like you. The shit has to WORK right out of the box. Stay safe! |
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have trashed the LMT bolt for a colt replacement. Bolt carrier is still LMT and seems ok. Time will tell.
Still on the hunt for a 14.5" barrel. The 10.5" has to go. It simply hasn't made the grade and I haven't got the patience or luxury of time to deal with symptomatic fixes only. It gets to work first time or it's ultimately heading for the trash heap. |
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skorp,
while shorties are traditionally finicky and LMT has their share of problems I think we should keep the baby and the bathwater in the tub for the time being. A heavier (H3) buffer is necessary for your configuration as well as increased extractor tension. Can you lay hands on an H3 from the links I sent? |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
Dudes potentially in contact don't have the time or luxury of messing with something that should have been de-bugged before deploying. I'd rather have a piece-o-sh!t AK that works every time than a high-speed cute, short carbine that I'm not sure of (and I am relying on for both my job and life insurance).
Skorp, just out of curiosity is this LMT bolt the one with two extractor springs? |
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tweak - will have a look at the links this am my time for buffer weights, thanks for the steer.
The LMT extractor was single spring. If I can find a 14.5" tube, it's going on for testing. Reliability is king. |
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What you're seeing is decades of advertizing coming to fruition, this is the end product of "mil spec" this and "usgi" that. Some bean counter thought it would be cheaper to "build their own" rifles rather than buy known good ones. If this rifle was his only one I'd recommend tossing it under the nearest armored vehicle but we do have the luxury of troubleshooting it as he does have an AK and he can't easily find replacement parts. He's stuck with it so we'e going to try and make it work and in the process maybe help a whole bunch of other folks who are stuck in the same situation. Eventually these civilian clowns (not the shooters but the paymasters) will figure out that there is a reason mil parts are more expensive. skorp, can you order one of the H3 buffers from your location? if not we'll make arrangements. ETA 4 pages for your reading pleasure |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
tweak - have managed to source an H2 buffer, and an armorer is going to either put an extra weight in it, or get an H3 buffer from somewhere
may also have a line on a 14.5" tube from a tried and tested mil-spec manufacturer. wait out on that one. skorp |
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Good deal.
Did you find my info dumpu useful BTW? |
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JLM
intel was of good value and will be disseminated accordingly here. thanks very much. skorp |
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thanks to a friendly armorer, have today managed to change over to a 14.5" colt heavy M4 barrel and will test fire tomorrow. Only downside was scratching of lock nut on Larue tactical forend rail system which was a complete b*stard to get off. Now it's got nasty gouges on both sides where the wrench bit into it. Anyone know some home fixes for cosmetic repairs?
have installed H2 buffer, still waiting for H3 - may just have to put extra weight into H2. Once o-rings rec'd, will install one, keep a couple of spares and distribute rest to armorer and other guys. goodbye LMT barrel with canted FSB. skorp |
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Thats pretty disappointing about the LMT barrel. All my LMT products have been great. FWIW, Wes Grant puts an O-ring in every 10.5 bolt he ships. Then he test fires 90 rounds really fast (he uses his RR M16 for that). It seems to be an almost mandatory modification.
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Veni, Vidi, volo in domum redire
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yep, it's disappointing. still, a lot of shorties are problem children and potential lack of reliability makes me extremely twitchy - and Iraq generates enough twitches on it's own without adding problematic equipment.
Zeroing the iron sights with a canted FSB was a complete b*stard. I almost ran out of right windage on my adjustable rear before it would zero at 25m. And that was a minor problem compared to extraction issues. A 14.5", with buffer and extractor fixes added will hopefully bring things back on line, plus will give me some extra velocity and energy on the target. I still have the LMT upper (colt bolt, mind you), so I haven't binned LMT completely..... |
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Probably a good thing, allthou LMT alledgedly does that Binned eh? I somehow suspected you were British |
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he had me at "slotted"
care package is still on hold pending an outcome, one other WA member wants throw in some items. O rings went out last week IIRC. |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
g'day
I shall not take offense at being mistaken for a brit, although as an aussie, it's a serious insult to be labelled as a 'whinging pom', or 'whinging pommie b*stard' (your preference - but say it with feeling). As fellow ex-colonials with your own proud history of hammering the brits for a spot of entertainment, I know you'll understand. On to other things. I test fired the M4 today and only got time for 5 mags (who knows if that's enough), which went through without any issue bar one. The bolt will not hold open on the last round. I did a function test at the beginning and the bolt will not hold open on any of the mags I tried, new or old. I don't know if this is a drama with the bolt catch or a gas issue. I suspect the former as it will not hold open when I put an empty mag on and cycle the action(?) Correct me if I'm wrong. When I push the bolt hold/release catch in manually, it catches the bolt in the correct position. skorp |
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again, thanks for all the advice and care packages. all items will be put to good use, both by me and the numerous other guys that need help, including the armorers.
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Skorp, check your bolt catch. A sub-standard one won't have enough projection on the front end to catch on the back end of the mag follower (forcing the catch up to lock the bolt and carrier to the rear).
"Ozzies I like. Ruperts, well..." |
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the bolt catch seems to either be binding, or is too stiff for the mag follower to push it all the way up.
bloody hell, if it's not one thing, it's another. can anyone recommend a good bolt catch and provide some instructions on the best way to get it out. that roll pin is a very small diameter. |
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Bolt catch assembly here:
http://www.ar15.com/content/guides/assembly/lower/#boltCatch Hopefully you can get a Colt or FN catch. Is it a LMT lower as well? Ozzie eh? Well all right Take care, and stay safe! |
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I'll try to get a colt bolt catch
Yeah, no hiding it - I'm an aussie. We have a couple of yanks on our team who have been made honorary aussies. took em' a while, but they got there. cheers |
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OK, let's get back on track,
Strip the bolt out of the carrier and slowly slide the carrier into the upper, feel for ANY resistance as the gas tube enters the carrier key. If there is any interference you can adjust the end of the gas tube with a large flatbladed screwdriver. Adjust the fit until the carrier closes without any interference. Then take your newly rebarreled rifle and drop a round in the chamber, drop the bolt, press in on the bolt catch, and fire the round. Repeat this test several times to be sure. If the bolt locks back properly you have a bolt catch/magazine problem. If it doesn't lock back you have a gas problem. The bolt catch only needs enough spring tension on it to hold it down, no more. Compare the fit and tension of your catch to other ARs that you have at hand. Less tension is better on a bolt catch up to the point that the catch starts engaging in the middle of a magazine. You should be able to deburr either the bolt catch slot or the catch itself and/or adjust the bolt catch spring. Make sure that there is not a disconnector spring under the bolt catch, it's been known to happen. You get this rifle fixed and we'll make you an honorary Seppo, then you can chat up Mr Lewis about his bodgy parts. JLM, It's a BFI lower, more "milspec" parts. |
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Moderation is for monks. RAH
It's a thankless job, luckily I have karma to burn. HEY YOU WASHINGTONIANS! http://ar15.com/forums/forum.html?b=8&f=15 |
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"History teaches us that men and nations behave wisely once they have exhausted all other alternatives."
-- Abba Eban |
Tweak
No resistance as bolt carrier key meets gas tube. Can't get the bloody bolt catch out as don't have anything to drive the pin out with. Will try to get it back to the armorer at some stage. Frustrating. It won't hold open when I put an empty mag on and pull the working parts to the rear, either. Will try the function test you described, when I can get on the range (who knows when that will be). @#$%^!!!! Honorary Septic, hmmm? |
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