AR Sponsor
Posted: 2/4/2014 5:02:32 PM EDT
| I know its been addressed here way too many times, WHAT AM I MISSING? HELP please!!!! Heres the "Low Down" 20" pencil barrel (port is drilled .096, yes ive ck,d) When removing ft sight I can see gas is in line with hole. No leakage from barrel/sight. No leakage gastube/sight. Tried 3 different known good carrier/bolt assys. Tried 3 different complete lowers, with buffer tubes springs,buffers. Polished chamber. Carriers have free movement in upper with 45 deg. tilt test. The only thing I haven't tried yet is different ammo (all 6 of my other AR,s run it just fine) Gas tube is not obstructed, and the mushroom fits very nice in key. When I say "Short Stroke",,,, weapon fires and I have to manually cycle bolt back to extract and feed another rd. Bolt will never go back far enough to lock open, or pick up another rd. Extractor doesn't seem to be leaving any undue stress on rim trying to pull rd out. What could I possibly be missing? At this point I,m almost ready to do a complete barrel swap???? What say you guys? THANKS for any and all input, Eric |
|
When you fire the weapon, is the gas pressure pushing the bolt carrier assembly enough so that it is unlocking the bolt at all from the barrel? If the bolt carrier assembly unlocking and traveling rearward, is it extracting the empty case, or is it leaving it behind in the chamber? When you have this malfunction, if the bolt carrier assembly is unlocking and going rearward, it is recocking the hammer?
CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
|
Quoted:
I know its been addressed here way too many times, WHAT AM I MISSING? HELP please!!!! Heres the "Low Down" 20" pencil barrel (port is drilled .096, yes ive ck,d) When removing ft sight I can see gas is in line with hole. No leakage from barrel/sight. No leakage gastube/sight. Tried 3 different known good carrier/bolt assys. Tried 3 different complete lowers, with buffer tubes springs,buffers. Polished chamber. Carriers have free movement in upper with 45 deg. tilt test. The only thing I haven't tried yet is different ammo (all 6 of my other AR,s run it just fine) Gas tube is not obstructed, and the mushroom fits very nice in key. When I say "Short Stroke",,,, weapon fires and I have to manually cycle bolt back to extract and feed another rd. Bolt will never go back far enough to lock open, or pick up another rd. Extractor doesn't seem to be leaving any undue stress on rim trying to pull rd out. What could I possibly be missing? At this point I,m almost ready to do a complete barrel swap???? What say you guys? THANKS for any and all input, Eric What kind of ammo are you using because this is probably your problem. If its not mil spec ammo it may short stroke. Tula will occasionally short stroke in my rifle length gas system. Until you've tried quality mil spec ammo don't even start thinking about barrel swaps. |
|
Quoted:
When you fire the weapon, is the gas pressure pushing the bolt carrier assembly enough so that it is unlocking the bolt at all from the barrel? If the bolt carrier assembly unlocking and traveling rearward, is it extracting the empty case, or is it leaving it behind in the chamber? When you have this malfunction, if the bolt carrier assembly is unlocking and going rearward, it is recocking the hammer? CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 sully, I too currently having the same issues with my AR M4 style rifle. Try cleaning the chanber like I just did using a good solvent or CLP and see what happens. On my next range outing I intend to see if this helps me. Other wise as I've been told my most likely repair would be the buffer and spring cuz it may be too heavy for the ammo I'm using. In addition try a different brand of ammo like American Eagle or Nato speced ammo. Right now I'm just 5-/50 using PMC Bronze. I think I need a hotter round to get he rifle to cycle it parts and then perhaps thing would improve. Impala |
|
Quoted:
What kind of ammo are you using because this is probably your problem. If its not mil spec ammo it may short stroke. Tula will occasionally short stroke in my rifle length gas system. Until you've tried quality mil spec ammo don't even start thinking about barrel swaps. Quoted:
Quoted:
I know its been addressed here way too many times, WHAT AM I MISSING? HELP please!!!! Heres the "Low Down" 20" pencil barrel (port is drilled .096, yes ive ck,d) When removing ft sight I can see gas is in line with hole. No leakage from barrel/sight. No leakage gastube/sight. Tried 3 different known good carrier/bolt assys. Tried 3 different complete lowers, with buffer tubes springs,buffers. Polished chamber. Carriers have free movement in upper with 45 deg. tilt test. The only thing I haven't tried yet is different ammo (all 6 of my other AR,s run it just fine) Gas tube is not obstructed, and the mushroom fits very nice in key. When I say "Short Stroke",,,, weapon fires and I have to manually cycle bolt back to extract and feed another rd. Bolt will never go back far enough to lock open, or pick up another rd. Extractor doesn't seem to be leaving any undue stress on rim trying to pull rd out. What could I possibly be missing? At this point I,m almost ready to do a complete barrel swap???? What say you guys? THANKS for any and all input, Eric What kind of ammo are you using because this is probably your problem. If its not mil spec ammo it may short stroke. Tula will occasionally short stroke in my rifle length gas system. Until you've tried quality mil spec ammo don't even start thinking about barrel swaps. I really don't know what kind of ammo it is. It is something ive had around here for yrs. I did try this exact ammo in my other SIX (6) AR,s and they all feed it "No Problem". Nope, I haven't tried another gas tube yet. |
|
With the upper run on different working lowers, run with different working B/C, and the gas system check for leaks/blockage at the gas block, it does narrow the problem down to the upper alone.
Guessing that you have check to make sure that a carrier with key alone does move freely in the upper receiver, the gas tube has been correctly aligned so it not binding on the carrier key, and even confirmed that the barrel was installed so the the bolt lugs enter and exist the barrel without binding as well. What has me thinking that the problem is a head space to cause the short stroking problems is that fact that you posted that you polished the chamber. So either the finish reaming on the barrel was just total shite to begin with, or the chamber was only rough reamed, and still not finished reamed to set the correct head space. Simply put, you would think that all barrels for the AR system would come finished reamed with the correct head space set for a standard bolt, but such is not the case. I can name a hand full of suppliers that send out barrels not finished reamed to set the correct head space, and this barrel is sounds to be one of them. Granted that gleaming the chamber walls does pretty up the first rough reaming, it does not set all the final chamber cuts to needed demensions. Point blank, before going any farther, get a Go test gauge to check the chamber dimensions/head space. |
|
Quoted:
I really don't know what kind of ammo it is. It is something ive had around here for yrs. I did try this exact ammo in my other SIX (6) AR,s and they all feed it "No Problem". I find your disclaimer disingenuous, as I can tell you where every round I've ever fired came from, at least as to gross country of origin, marked brand and rough year of acquisition, and I've been doing this almost 20 years now. However, as this is a tech forum I'll presume you're serious and tell you that ammo has this thing called a "headstamp" - a picture or description of it will help us narrow it down quite a bit. As you've seen from experience, the fact that it works in your other SIX (6) ARs isn't helping with this upper and its ammo sample size of ONE (1). If you just don't want to tell us what you're running, please say so - we'll try to help you anyway. |
|
Quoted:
I find your disclaimer disingenuous, as I can tell you where every round I've ever fired came from, at least as to gross country of origin, marked brand and rough year of acquisition, and I've been doing this almost 20 years now. However, as this is a tech forum I'll presume you're serious and tell you that ammo has this thing called a "headstamp" - a picture or description of it will help us narrow it down quite a bit. As you've seen from experience, the fact that it works in your other SIX (6) ARs isn't helping with this upper and its ammo sample size of ONE (1). If you just don't want to tell us what you're running, please say so - we'll try to help you anyway. Quoted:
Quoted:
I really don't know what kind of ammo it is. It is something ive had around here for yrs. I did try this exact ammo in my other SIX (6) AR,s and they all feed it "No Problem". I find your disclaimer disingenuous, as I can tell you where every round I've ever fired came from, at least as to gross country of origin, marked brand and rough year of acquisition, and I've been doing this almost 20 years now. However, as this is a tech forum I'll presume you're serious and tell you that ammo has this thing called a "headstamp" - a picture or description of it will help us narrow it down quite a bit. As you've seen from experience, the fact that it works in your other SIX (6) ARs isn't helping with this upper and its ammo sample size of ONE (1). If you just don't want to tell us what you're running, please say so - we'll try to help you anyway. Circuits I understand your thinking "disingenuous" OK, I,ll explain.. In 1990 I belonged to a Naval Reserve unit that couldn't/wouldn't? get funds for ammo on our annual quals. . I would buy large amounts of ammo and bring it to the reserve center, put it in smaller bags and sell it at my cost to the guys that wouldn't bring ammo. I know, your next question is going to be about armory weapons and not being allowed to shoot just any ammo from god knows where. Noooo we weren't using armory weapons, we brought our own (well, at least the guys that owned AR,s) We also had to find our own range (one of our members was a police officer in his civilian job, so he would get access to a range) So, I do have lots and lots of leftovers from 23yrs ago that eventually just got all thrown together as I lost track of what was what. I hope this clarifies things for you? I really wouldn't like to go into detail as to what unit, or what state this outfit was from, as it always seemed a little embarrassing and unbelieveable that this is actually possible. If need be, I can send you a personal e-mail to fill in the blanks just a little better? If your eluding to maybe I,m trying to shoot steel stuff,,,,,no, It is brass. I dont know what kind, and the only reason I stated that my other six AR,s shoot it with no problem is so that maybe that could have eliminated one of the parameters. So its not that I don't want to tell you. "Ammo sample size of (1)" ??? I really don't understand this statement. Of course none of this long explanation got us any closer to a solution. |
|
Any idea of what brand of barrel? How long have you had it, and is there any idea of round count? Is it set up with a front sight base that is pinned or screwed into place? You state that the gas port checked at .096", when you measured it did you check to see if there were any obstructions inside the gas port or inside of the gas block/front sight base? When the brass case fails to eject, are there any tell tale signs of anything on the brass case where it would show signs of sticking or dragging? Have you tried using a different gas tube, as it is possible that it may be obstructed? On the back end of the gas tube, about the last 1/8", there is a slightly flared section that is known as a bell, this bell helps create a seal inside the bolt carrier key (gas key), is the bell present? You state that you have tried different bolt carriers, does this include trying different bolts? Have you tried any other ammunition?
CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
| I got the barrel from AR15Sport, last summer, it is new, and I only have approx. 90rds though it, (it / this weapon has never functioned properly) I did contact them and they were most helpful with having me ck the gas port hole size. The sight is pinned on, I have taken the sight back off to make sure the gas is hitting the hole properly. The gas tube "bell" fits very nice inside of the key. (actually a precision fit, meaning a little more snug then the other gas tubes I have) Yes, I did try different bolts along with different carriers. Now I,m beginning to wonder if this tighter fitting tube might be the problem? when sliding the carrier by hand, it does slide freely in the upper, and doesn't seem to bind at all when the key goes onto the bell of the tube. I hope in the next week to try a different gas tube. I have examined the brass after firing and manually ejecting it (it doesn't show any signs of excessive scrathing and the base of the shell doesn't look like the extractor is putting undo pulling action on the brass. I,ll keep you guys posted, as I know whatever the problem is, surely someday somebody else will be plagued with a similar issue. And, no I haven't taken the time to buy any more ammo and try it although you have me curious. I guess I,m kinda hard headed, as i really have been shooting this ammo for quite some time with no problems in the other ARs, I really really appreciate all of the GREAT input. Thanks guys |
|
Quoted:
So its not that I don't want to tell you. "Ammo sample size of (1)" ??? I really don't understand this statement. Of course none of this long explanation got us any closer to a solution. The relevance of the sample size is the ammo may just be marginal, and it's coming out in this one upper. I have a sample size of TWENTY (20) different 5.56 rifles, some of which just won't run some ammo. All are fine if I feed them some M193 or M855, and some just plain don't run properly on certain makes of ammo. I'm not a steel hater, and in fact run steel almost exclusively (Brown Bear/Silver Bear the past decade or so), but not all steel is the same any more than all brass is the same. I've had brass loadings that just plain don't work well in all my rifles, either. That's the reason I brought up the ammo sample size. Now, if the reasoning behind your sticking only with this ammo is that it's all you have, or all you care to try to run, OK - though that may lead to just getting rid of this problematic upper. |
AR Sponsor