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Posted: 4/17/2010 4:57:19 PM EDT
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i picked up a dti ar 15 from a gun show about 3 weeks ago . m4 with a yhm quad rail ...
only thing i did was put on a different stock so far ... i took it out to shoot a few rounds remington uga or something (brass case ) . i never shot or had an ar before either . i racked in a new round and pulled the trigger and it shot one round but wouldn't shoot a second ??? so i rack out that round and it has a very light fireing pin shot on it ??? i rack in another round and it shots but won't shoot again and has same fireing spot on it ??? so i shoot , then have to rack in another round and when i do the other round ejects . seems something weird is happening and i keep haveing these half fired rounds every time i pulled the trigger ? any ideas guys ???? thanks |
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There will be a light strike everytime a round is chambered. What you need to figure out is if your trigger is breaking the second time or not.
Clean it thoroughly, then try her again. If the problem persists, take it to a gunsmith. btw, is the gun new or used? ETA: you dont need any tools to strip it ETA2: is the spent round ejecting? |
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No offence but can you try to reword this so it’s easier to understand?
I can’t quite figure out what you are saying. IF it is this: You load the rifle and chamber a round. Then press the trigger and the gun fires, the rifle then cycles normally (ejects and loads another round) but it will not fire again. When you manually eject that round it has a slight firing pin dimple then: The dimple is normal; the rifle not firing again is not. If that’s the case the gas system may be fine (it may not be also), however something is causing the trigger to not reset. My advice is to get some good quality 5.56 ammo; federal XM193, M885, black hills ect and fire the gun again, if it runs fine then the issue was ammo related and your problem is most likly solved. If it does the same thing again then take it to a local gun smith who knows the AR15 and take the gun to them and have them look at it. It is likly something in the gas system or the trigger group. Ok now if THIS is the problem: You load the rifle as before and pull the trigger and the gun goes off but does not eject the spent case and cycle; then yes there is defiantly something wrong with the gas system. My advice is to find a local gun smith who knows the AR15 and take the gun to them and have them look at it. It may also be related to you changing stocks, can you tell us what you did here? Did you just swap colapsible stocks? or did you change the buffer tube and buffer? Just changing stocks should not have done anything, but if you changed the tube, spring, buffer ect all of that could cause issues but we will need detailed information from you. |
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spent round is ejecting , new round is loading but not firing . so i pull the chargeing hammer and it ejects the unfired
round a loads a new one and then fires fine . at first i thought the fireing pin was just hitting to light some times but it happened over and over . four times before i was getting worried about half fired rounds on the ground . gun was used , flat top , in very nice shape ... i paid $750 |
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So what you are saying is it fires the first round and then strips another round from the mag and chambers it but does not go bang the second time when the trigger is pulled? Is the gun new or used?
ETA .. ya that sounds like a fire control group problem. Give it a good cleaning first. Could be a weak or improperly installed hammer spring .. may want to check that while cleaning it. |
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i changed the stock and buffer tube , mil spec tube and mugpul acs stock . i had a little trouble getting every thing working right with the detent and spring under the buffer tube .
i push the detent retainer down and screw the buffer tube on untill it covers up the detent half way . maybe i should be screwing the buffer tube on more so that the tip of the buffer retainer is under the stock tube also ? but then the buffer would rest totaly on the bolt and not let me open the upper and lower easy ... still learning sorry Quoted:
No offence but can you try to reword this so it’s easier to understand? I can’t quite figure out what you are saying. IF it is this: You load the rifle and chamber a round. Then press the trigger and the gun fires, the rifle then cycles normally (ejects and loads another round) but it will not fire again. When you manually eject that round it has a slight firing pin dimple then: The dimple is normal; the rifle not firing again is not. If that’s the case the gas system may be fine (it may not be also), however something is causing the trigger to not reset. My advice is to get some good quality 5.56 ammo; federal XM193, M885, black hills ect and fire the gun again, if it runs fine then the issue was ammo related and your problem is most likly solved. If it does the same thing again then take it to a local gun smith who knows the AR15 and take the gun to them and have them look at it. It is likly something in the gas system or the trigger group. Ok now if THIS is the problem: You load the rifle as before and pull the trigger and the gun goes off but does not eject the spent case and cycle; then yes there is defiantly something wrong with the gas system. My advice is to find a local gun smith who knows the AR15 and take the gun to them and have them look at it. It may also be related to you changing stocks, can you tell us what you did here? Did you just swap colapsible stocks? or did you change the buffer tube and buffer? Just changing stocks should not have done anything, but if you changed the tube, spring, buffer ect all of that could cause issues but we will need detailed information from you. |
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if the trigger is not resetting , then when i pulled the chargeing handle would that rest the trigger ? Quoted:
Sounds like the hammer is not resetting. Yes that is why it is firing after you charge it. Your buffer tube seems to be installed correctly. However, fire control seems to be the problem here. ALWAYS clean a new or used rifle before you shoot it. Is there anything irregular about the trigger? Take it to a gunsmith. Best advice. And clean it, of course. |
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i have built many custom 10/22 's and do alot of tigger mods . i am planing to break the ar down and learning to do some tigger work to the stock tigger .
i wanted to make sure every thing is working correct before i do so . it does seem like the tigger may not be resetting and if the light dent in the primer is common from just loading then all may not be that bad . i will hopefully work out what ever is wrong with out going to a gun smith ... |
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here is a picture
http://img62.imageshack.us/img62/512/img2241w.th.jpg http://img535.imageshack.us/img535/786/img2243r.th.jpg i can't seem to get my flash hider to tighten up with the solid slot on the bottom ... any ideas ??? |
 We are getting some place!
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spent round is ejecting , new round is loading but not firing . so i pull the chargeing hammer and it ejects the unfired round a loads a new one and then fires fine . Ok GOOD! We know more now. I also read what you had to say about the stock. My guess is the stock is fine, if you got it all together with the detent in you should be GTG. As has been said the trigger is not resetting, reason is unknown, may be the fire control group may be bad ammo and may still be the gas system. If it’s bad ammo or the gas system what is happening is there is not enough energy (gas) to cycle the gun, eject and load a new round but the bolt is not going far enough rear ward to trip the reset on the trigger group. This can be bad ammo, gas issues or a combo of both. It could be that the gas and ammo is just fine but there is a problem with the trigger group. Fix there is replace trigger group (I would put a whole new mil spec kit in they are cheap and not try to figure out what part of 8 it is, but that’s just me). Do this; clean the gun and put the rifle together in normal working order. UNLOAD AND CLEAR THE WEAPON. PUT ALL AMMO IN THE OTHER ROOM NO WHERE NEAR YOU. Ok now that the legal disclaimer is out of the way 
Charge the gun and dry fire it, HOLD THE TRIGGER TO THE REAR (no ammo in a safe direction yada yada...). Charge the gun again HOLDING THE TRIGGER TO THE REAR. The trigger should reset when you do this. With the gun pointed in a safe direction release the trigger, you should hear a click that is the trigger resetting. Pull the trigger; the hammer should fall. If it does this (do it a few times) then the odds are the trigger group is just fine. Your issue is gas/ammo related. I would again try new good ammo again and then take the gun to a smith if the problem persists. If you want bring the problem back to us we can walk you thrue everything but it could be a bunch of little things. If it does NOT reset then the problem is in the trigger group. Buy a new trigger group and install it. If you have done your own 10/22 triggers you can install an AR15 trigger they are not hard at all, see the building it yourself forum there is a sticky with EVERY thing you need to know. |
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Single loaded round in a mag, mag insert and soul round fired with the empty mag still in the mag well,
Bolt should lock back, and we can rule out short stroking. So lets say that you are good and not short stroking, which would mean that the gas system is ok, it's just that the bolt is either not fulling locking up, or the disco is not releasing the hammer when the B/C goes home. On the gas tube, with the bolt out of the carrrier, insert just the carrier and confirm that the carrier gas tube and carrier are aligning correctly. If needed, tweak the gas tube above the barrel to get the correct index. On the lower, pull the upper off completly. As stated above, pull the trigger all the way back, cock the hammer to the disconnector sear, then slowly release the trigger while keeping your hand in front of the hammer so is something goes wrong, it does not crash into the front of the receiver. If the disco spring is installed large coils side down into the back of the trigger slot, the trigger and hammer spring installed correctly wound with the hammer legs on top of the trigger pin, the FCG pin and parts where lubed correctly, no FCG parts binding on the either the side of the receiver or C slot in the selector, and the back hammer and disco sear are edge bur free, then the hammer should be released from the disco as you release the trigger and caught/retained by the front hammer sear. So lets say that you have done a few FCG checks and they are golden as well, lets move on to the Firing pin. On the firing pin, its stop collar edge should be flush or slightly lower than the carrier ramp. If the stop collar is protruding past the carrier ramp when seated against such, then it may be that your hammer is catching that edge, and why the B/C is being slowed down to not fully lock home. Other problems could be as well here, carrier key tight in the upper slot and slowing the forward movement of the B/C home, or even the barrel extension lugs not aligned correctly and the bolt lugs not aligning up as well. Lastly, which was stated first, you do need to fully clean the rifle and barrel before it's shot the first time. The rest of the parts can just be cleaned with CLP, but the chamber and bore will need a goo solvent scrubbing with the help of a chamber brush by hand. The once the rifle is clean, lube the upper bearing areas (including the B/C inside and out) with CLP on the wetter side for break in. Run through the check list, and get back to us on what of the above portion is the failure. |
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if the rifle is ejecting the spent casing and loading a fresh round the trigger should reset, the BCG only needs to travel about an inch to the rear to reset the hammer.
i'v read this a couple of times, and I keep coming back to the disco. it sounds to me like the disco may be sticking and NOT catching the hammer, allowing the hammer to ride the back of the BCG back into battery. normally this would result in burning off all or part of the ammo in the mag. but if you have weak springs in a used gun it might not have enough power to touch off a round when slowed by the BCG. the stuck disco would cause the hammer to drag on the BCG slowing it enough to not fully goto the rear(while still cycling) but still allowing you to cock it by manually cycling the action with the charging handle. or it may be that the disco it self is out of spec. I used to work for DPMS making AR's, last year we got a batch of bad discos, they seemed to work fine when most ppl check the FCG for function. if you dry fired and released the trigger fast it worked fine. if you cycled it with your finger off the trigger it worked fine. but if you dry fired, held the trigger to the rear, and slowly released to the trigger reset, the hammer would fall instead of resetting. (dont worry, the bad batch was caught the day it came in, and every disco in the building was removed, we had to wait a week to get good ones back in) you can check by taking off your upper, and using something to push down on the back side of the disco. there should be about an 1/8th inch of travel and it should spring back freely and immediately without any hangups. also very slowly check the FCG function. again with the upper off, dry fire and hold the trigger tightly to the rear. reset the hammer, it should lock down with very little effort. then very very slowly release the trigger. after a short travel you should hear a pop as the hammer resets. |
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With hammer follow through due to the disc not retaining the hammer correctly, on un-shrouded carriers with L cut hammers, the B/C is going to lock up about half way forward.
On shrouded carries with m16 type rounded hammers, the follower through is going to end up with a hammer down on a unfired round. Follow through does not have enough energy to ignite standard primers since although the hammer is on the firing pin, the firing pin will not make contact with the primer until the bolt locks home (back of carrier blocking such until bolt cams). |
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