User Panel
User Panel
User Panel
|
Posted: 1/14/2017 6:25:51 PM EDT
[#1]
Sounds under gassed based on not locking back. By failure to feed is the bolt sitting on top of the base of the round or what exactly?
Carbine buffer? |
|
|
|
Posted: 1/14/2017 6:57:48 PM EDT
[#2]
Under gassed. Check gas block alignment, if that is fine, then I would check port size
|
|
|
|
Posted: 1/14/2017 7:39:55 PM EDT
[#3]
Well I had the barrel installed on the upper by John Thomas so I'm quite sure that it
is lined up correctly. Now I do have a carbine buffer and spring installed, could that be the cause of this? |
|
|
|
Posted: 1/14/2017 10:16:53 PM EDT
[#4]
Last year I built a truck gun around a 16" BCM middy barrel I had. Put a low pro gas block under a BCM KMR-A hand guard. Rifle wouldn't run anything but 556 loads. That barrel had ate anything I stuck in it in its formal life.
I changed buffers, springs, etc and finally pulled it apart and measure the gas port hole locations relative to the barrel and the gas block. Low and behold there was about .020" difference. With the gas block aligned correctly, it is back to running like a raped ape. |
|
|
|
Posted: 1/15/2017 2:42:16 AM EDT
[#5]
Try some different magazines. Bolt catch operates freely and its spring has sufficient tension ?
|
|
|
|
Posted: 1/15/2017 8:45:44 AM EDT
[#6]
Quote HistoryQuoted:
Try some different magazines. Bolt catch operates freely and its spring has sufficient tension ? I had a couple of different magazines and it happened on each one, bolt catch appears to be fine. |
|
|
|
Posted: 1/15/2017 2:03:15 PM EDT
[#7]
Quoted:
The rifle started out as a Aero Precision AC-15, I changed out the barrel with a PSA mid length Freedom and a A1/C7 upper the lower has remained the same internally I just changed the stock to a retro CAR stock. While shooting I was using Mag Pul Gen 2 30 rd mags and on 4 separate occasions I had a failure to feed also failure to lock the bolt back after the last round. The ammo that I was using was Federal 55 gr AE and Remington 55 gr. What gives? Buffer weight? |
|
|
|
Posted: 1/15/2017 3:20:20 PM EDT
[#8]
Quoted:
I had a couple of different magazines and it happened on each one, bolt catch appears to be fine. Different, as in not Magpul ? |
|
|
|
Posted: 1/15/2017 4:13:56 PM EDT
[#9]
No same type of mag and manufacturer just a different one.
|
|
|
|
Posted: 1/15/2017 6:09:38 PM EDT
[#10]
Try a different, not made by Magpul, magazine.
|
|
|
|
Posted: 1/15/2017 7:24:28 PM EDT
[#11]
Watch the direction of your ejecting brass.
Surprised no on has suggested this. Your ejecting brass will give you an indication (not a solid answer, but at least an indication) of what your gas system is doing. What are you seeing? |
|
|
|
Posted: 1/15/2017 8:46:44 PM EDT
[#12]
Quote HistoryQuoted:
Watch the direction of your ejecting brass. Surprised no on has suggested this. Your ejecting brass will give you an indication (not a solid answer, but at least an indication) of what your gas system is doing. What are you seeing? Oh God, are we going to do the chart again? 
|
|
|
|
Posted: 1/15/2017 11:59:23 PM EDT
[#13]
Need a lighter buffer weight. The buffer comes apart so you can remove weights and retest. That's the cheap and quick way to test.
|
|
|
|
Posted: 1/16/2017 3:32:24 AM EDT
[#14]
Quote HistoryQuoted:
Need a lighter buffer weight. The buffer comes apart so you can remove weights and retest. That's the cheap and quick way to test. No he does not need a lighter buffer weight, first off he's already running the lightest common buffer weight, second a reasonable upper setup should cycle with essentially any buffer weight. Gas block misalignment is common almost to the point of ubiquitous these days. Rotate the gas block 180 degrees on the barrel so you can see how far off the handguard retainer shoulder it should be, then make sure it's aligned vertically correctly and see if that doesn't fix the problem. The gas port needs to be reasonably centered in the hole in the gas block, and make sure your gas tube is lined up in the gas block as well. |
|
|
|
Posted: 1/17/2017 5:23:44 PM EDT
[#15]
I have an A2 front sight base and it does not appear to be leaking excessively, this is my
my first midlength barrel and I was not aware that they might be ammo sensitive. |
|
|
|
Posted: 1/17/2017 6:21:31 PM EDT
[#16]
Does sound under gassed to me also. Double check the gas port just to be safe, but I am going to trust you on it being good.
I think the 1st thing I would do is pull some weight out of the buffer to get things moving a little faster. Keep an eye on where the extractor yanks on the cases to make sure you don't start seeing signs of pulling out early. Could also try a lighter buffer spring to let things move easier. If you have an extra laying around, you could start cutting off coils to soften it up as an experiment. This should allow you to run the current buffer to delay extraction, but let the bcg move further after it gets moving. Get too extreme here and my guess is the buffer is going to bottom harder in the buffer tube (more felt recoil), or not enough spring to drive a round out of the mag. I think many mfg overgass these things from the getgo to minimize the number of phone calls they get. This may help in reliability, but not always the smoothest shooting rifle. These things are very tuneable, and doing so can yield some very noticeable results. Keep in mind though, the finer you tune it, the more finicky it may become with ammo or being ran dirty. Overgassing is the easy way to gain some headroom on these. |
|
|
|
Posted: 1/17/2017 7:51:35 PM EDT
[#17]
Those us who have been reluctant to jump on the 16" middie bandwagon, are seeing more and more threads like this in which their middies are clearly undergassed for all but full power 5.56 NATO ammo. I fully understand the argument that carbine gas port 16" barrels are supposed to have the wrong dwell time and tend to be overgassed. Yes, I get that.
But, I'd much rather have a reliable 16" barreled rifle that will shoot everything thrown through its magazine, come hell or high water. A carbine gas port location might have a bit more bolt velocity and might have a bit more muzzle rise, but it simply works. As far as I know Colt is still running a carbine gas port on its 16" barrel 6920LE carbines, and most guys here think that Colt is the second coming. My two 16" barrel carbines with carbine gas ports are both shooting everything flawlessly. On one, a precision build with a match grade barrel (yes, carbine gas port), I did H2 buffer it, but the other is still running the carbine buffer. I'm still reluctant to accept that the theory of dwell mismatch, as scientifically valid as it is, translates in the real world field to an acceptably reliable 16" barrel when the gas port is in the "middie" location. I really think the carbine gas port location for 16" barrels makes more sense unless you actually intend to shoot primarily M855 or M193 full power 5.56. I really hope OP finds out that it's a magazine problem or something else. I would not be surprised to find out, however, that he is stuck with a barrel that only shoots full power 5.56 ammo reliably. |
|
|
|
Posted: 1/17/2017 8:50:53 PM EDT
[#18]
Quote HistoryQuoted:
Those us who have been reluctant to jump on the 16" middie bandwagon, are seeing more and more threads like this in which their middies are clearly undergassed for all but full power 5.56 NATO ammo. I fully understand the argument that carbine gas port 16" barrels are supposed to have the wrong dwell time and tend to be overgassed. Yes, I get that. But, I'd much rather have a reliable 16" barreled rifle that will shoot everything thrown through its magazine, come hell or high water. A carbine gas port location might have a bit more bolt velocity and might have a bit more muzzle rise, but it simply works. As far as I know Colt is still running a carbine gas port on its 16" barrel 6920LE carbines, and most guys here think that Colt is the second coming. My two 16" barrel carbines with carbine gas ports are both shooting everything flawlessly. On one, a precision build with a match grade barrel (yes, carbine gas port), I did H2 buffer it, but the other is still running the carbine buffer. I'm still reluctant to accept that the theory of dwell mismatch, as scientifically valid as it is, translates in the real world field to an acceptably reliable 16" barrel when the gas port is in the "middie" location. I really think the carbine gas port location for 16' barrels makes more sense unless you actually intend to shoot primarily M855 or M193 full power 5.56. I really hope OP finds out that it's a magazine problem or something else. I would not be surprised to find out, however, that he is stuck with a barrel that only shoots full power 5.56 ammo reliably. Ive got a 14.5" middy and 16" middy, both are BCM and running H2 buffers. They eat anything I feed them, always have. They prob have around 4-5K rounds down the tube of Wolf MC, Brown Bear, Fed 193, Privi 193 / 855, with the largest percentage being Brown Bear. |
|
|
|
Posted: 1/17/2017 8:51:12 PM EDT
[#19]
So will a midlength have problems firing .223 ammunition. I'm swapping for a BCM midlength 16 upper and putting it on my mp sport
|
|
|
|
Posted: 1/18/2017 12:05:21 AM EDT
[#20]
Quote HistoryQuoted:
So will a midlength have problems firing .223 ammunition. I'm swapping for a BCM midlength 16 upper and putting it on my mp sport |
|
|
|
Posted: 1/18/2017 12:15:18 AM EDT
[#21]
OP, I would suggest you pull the front sight post off and confirm gas port hole is cleanly drilled and proper size in barrel and sight post. Also suggest you measure the location of gas hole from the step in the barrel, and measure the gas hole location in the front sight as well - confirm those measurements match.
Dont trust the smith "done it right", anyone can make a mistake and could've overlooked bad parts (issue with gas ports). only way you will KNOW and be able to rule it out is to see for yourself. |
|
|
|
Posted: 1/18/2017 2:11:04 PM EDT
[#22]
Quote HistoryQuoted:
Those us who have been reluctant to jump on the 16" middie bandwagon, are seeing more and more threads like this in which their middies are clearly undergassed for all but full power 5.56 NATO ammo. I fully understand the argument that carbine gas port 16" barrels are supposed to have the wrong dwell time and tend to be overgassed. Yes, I get that. But, I'd much rather have a reliable 16" barreled rifle that will shoot everything thrown through its magazine, come hell or high water. A carbine gas port location might have a bit more bolt velocity and might have a bit more muzzle rise, but it simply works. As far as I know Colt is still running a carbine gas port on its 16" barrel 6920LE carbines, and most guys here think that Colt is the second coming. My two 16" barrel carbines with carbine gas ports are both shooting everything flawlessly. On one, a precision build with a match grade barrel (yes, carbine gas port), I did H2 buffer it, but the other is still running the carbine buffer. I'm still reluctant to accept that the theory of dwell mismatch, as scientifically valid as it is, translates in the real world field to an acceptably reliable 16" barrel when the gas port is in the "middie" location. I really think the carbine gas port location for 16' barrels makes more sense unless you actually intend to shoot primarily M855 or M193 full power 5.56. I really hope OP finds out that it's a magazine problem or something else. I would not be surprised to find out, however, that he is stuck with a barrel that only shoots full power 5.56 ammo reliably. I disagree that there's anything inherently wrong with a mid length gas system. There are simply too many out there that work fine. If you have to feed your AR 556 only to make it work, there's an issue, but it's not simply inherent in mid length gas systems. |
|
|
|
Posted: 1/18/2017 2:39:19 PM EDT
[#23]
Quote HistoryQuoted:
I disagree that there's anything inherently wrong with a mid length gas system. There are simply too many out there that work fine. If you have to feed your AR 556 only to make it work, there's an issue, but it's not simply inherent in mid length gas systems. Quote HistoryQuoted:
Quoted:
Those us who have been reluctant to jump on the 16" middie bandwagon, are seeing more and more threads like this in which their middies are clearly undergassed for all but full power 5.56 NATO ammo. I fully understand the argument that carbine gas port 16" barrels are supposed to have the wrong dwell time and tend to be overgassed. Yes, I get that. But, I'd much rather have a reliable 16" barreled rifle that will shoot everything thrown through its magazine, come hell or high water. A carbine gas port location might have a bit more bolt velocity and might have a bit more muzzle rise, but it simply works. As far as I know Colt is still running a carbine gas port on its 16" barrel 6920LE carbines, and most guys here think that Colt is the second coming. My two 16" barrel carbines with carbine gas ports are both shooting everything flawlessly. On one, a precision build with a match grade barrel (yes, carbine gas port), I did H2 buffer it, but the other is still running the carbine buffer. I'm still reluctant to accept that the theory of dwell mismatch, as scientifically valid as it is, translates in the real world field to an acceptably reliable 16" barrel when the gas port is in the "middie" location. I really think the carbine gas port location for 16' barrels makes more sense unless you actually intend to shoot primarily M855 or M193 full power 5.56. I really hope OP finds out that it's a magazine problem or something else. I would not be surprised to find out, however, that he is stuck with a barrel that only shoots full power 5.56 ammo reliably. I disagree that there's anything inherently wrong with a mid length gas system. There are simply too many out there that work fine. If you have to feed your AR 556 only to make it work, there's an issue, but it's not simply inherent in mid length gas systems. Understood, but why, then are there so many reported issues like this? Is gas block alignment so sensitive on mid length barrels? Seems not to be the case for barrels with carbine port location and typical port size, which is generous (perhaps overly so, but uber reliable) with most barrel makers. |
|
|
|
Posted: 1/18/2017 11:57:42 PM EDT
[#24]
Quote HistoryQuoted:
Understood, but why, then are there so many reported issues like this? Quote HistoryQuoted:
Understood, but why, then are there so many reported issues like this? Because there are a zillion makers of cheap barrels and other parts, and a zillion people putting them together in their garages who may or may not have any idea of what they are doing. Example for dramatic effect: This gun worked fine, but I replaced the front sight base with a low profile gas block, and put in a (tacticool of the day) BCG and buffer and recoil spring and {whatever} and now it's short stroking, help! As we see somewhat frequently on AR15.com, is not an indictment of the midlength gas system. There are plenty of people who can't seem to get their rifle length gas and other builds to work either. And plenty of times people have had trouble with a barrel, and eventually figure out that the manufacturer put a carbine size gas port in the barrel. Is gas block alignment so sensitive on mid length barrels? Gas block alignment is sensitive on any barrel regardless of gas tube length. Seems not to be the case for barrels with carbine port location and typical port size, which is generous (perhaps overly so, but uber reliable) Excessive gas in a mistimed barrel is not a recipe for "uber reliability". I will say, again, for all the folks who reflexively bash midlength gas setups - let's see your criticism of the obviously unreliable KAC E3 gas system length. Midlength is 2" longer than carbine, and the E3 length is 1.4 inches longer yet, so if midlength is unreliable, then the E3's should be terrible. Come on, let's see the criticism from the peanut gallery. A proper midlength 16" barrel is more reliable then a carbine, all other things being equal. Midlength has a larger operating envelope so can adapt for a greater variety of conditions. An example of this was the Lucky Gunner 10,000 round test, where they ended up using a midlength gas configuration rifle to complete the test with Tula ammunition due to too many malfunctions with the original test carbine gas. Tula is well known to have an odd pressure curve. If anyone remembers the Radway Green surplus ammo from years ago, it also would generally choke in a carbine gas rifle, but runs fine in a midlength. Conversely, full power M855 runs smoother in the exact same midlength gas setup with the same buffer. |
|
|
|
Posted: 1/19/2017 12:32:52 AM EDT
[#25]
Quote HistoryQuoted:
Because there are a zillion makers of cheap barrels and other parts, and a zillion people putting them together in their garages who may or may not have any idea of what they are doing. As we see somewhat frequently on AR15.com, is not an indictment of the midlength gas system. There are plenty of people who can't seem to get their rifle length gas and other builds to work either. And plenty of times people have had trouble with a barrel, and eventually figure out that the manufacturer put a carbine size gas port in the barrel. Gas block alignment is sensitive on any barrel regardless of gas tube length. Excessive gas in a mistimed barrel is not a recipe for "uber reliability". I will say, again, for all the folks who reflexively bash midlength gas setups - let's see your criticism of the obviously unreliable KAC E3 gas system length. Midlength is 2" longer than carbine, and the E3 length is 1.4 inches longer yet, so if midlength is unreliable, then the E3's should be terrible. Come on, let's see the criticism from the peanut gallery. A proper midlength 16" barrel is more reliable then a carbine, all other things being equal. Midlength has a larger operating envelope so can adapt for a greater variety of conditions. An example of this was the Lucky Gunner 10,000 round test, where they ended up using a midlength gas configuration rifle to complete the test with Tula ammunition due to too many malfunctions with the original test carbine gas. Tula is well known to have an odd pressure curve. If anyone remembers the Radway Green surplus ammo from years ago, it also would generally choke in a carbine gas rifle, but runs fine in a midlength. Conversely, full power M855 runs smoother in the exact same midlength gas setup with the same buffer. Quote HistoryQuoted:
Quoted:
Understood, but why, then are there so many reported issues like this? Because there are a zillion makers of cheap barrels and other parts, and a zillion people putting them together in their garages who may or may not have any idea of what they are doing. Example for dramatic effect: This gun worked fine, but I replaced the front sight base with a low profile gas block, and put in a (tacticool of the day) BCG and buffer and recoil spring and {whatever} and now it's short stroking, help! As we see somewhat frequently on AR15.com, is not an indictment of the midlength gas system. There are plenty of people who can't seem to get their rifle length gas and other builds to work either. And plenty of times people have had trouble with a barrel, and eventually figure out that the manufacturer put a carbine size gas port in the barrel. Is gas block alignment so sensitive on mid length barrels? Gas block alignment is sensitive on any barrel regardless of gas tube length. Seems not to be the case for barrels with carbine port location and typical port size, which is generous (perhaps overly so, but uber reliable) Excessive gas in a mistimed barrel is not a recipe for "uber reliability". I will say, again, for all the folks who reflexively bash midlength gas setups - let's see your criticism of the obviously unreliable KAC E3 gas system length. Midlength is 2" longer than carbine, and the E3 length is 1.4 inches longer yet, so if midlength is unreliable, then the E3's should be terrible. Come on, let's see the criticism from the peanut gallery. A proper midlength 16" barrel is more reliable then a carbine, all other things being equal. Midlength has a larger operating envelope so can adapt for a greater variety of conditions. An example of this was the Lucky Gunner 10,000 round test, where they ended up using a midlength gas configuration rifle to complete the test with Tula ammunition due to too many malfunctions with the original test carbine gas. Tula is well known to have an odd pressure curve. If anyone remembers the Radway Green surplus ammo from years ago, it also would generally choke in a carbine gas rifle, but runs fine in a midlength. Conversely, full power M855 runs smoother in the exact same midlength gas setup with the same buffer. In short, are you saying that a Colt 6920LE is unreliable? That's gonna be a hard sell. |
|
|
|
Posted: 1/19/2017 3:50:42 AM EDT
[#26]
I don't see where he says that at all
He says many of the probs with with any configuration are caused by the diy crowd. The article he mentioned seems to indicate a few rifles, 1 being a mid, were more reliable than a particular Bushy carbine with Tula ammo. He does say mids should be more reliable than carbines, but I don't see anywhere that he says carbines, or 6920s, are unreliable. This I am curious about though. I would have guessed the carbine would have a larger envelope with more bbl after the port. |
|
|
|
Posted: 1/19/2017 10:06:56 AM EDT
[#27]
Quote HistoryQuoted:
Understood, but why, then are there so many reported issues like this? Is gas block alignment so sensitive on mid length barrels? Seems not to be the case for barrels with carbine port location and typical port size, which is generous (perhaps overly so, but uber reliable) with most barrel makers. Because more and more people are opting for midlength barrels and there are more and more of them available. Increasing number of midlength builds and corresponding decrease in carbine builds = more midlength problems posted. For a 16" barrel, the midlength gas setup is a superior solution. |
|
|
|
Posted: 1/19/2017 10:19:15 AM EDT
[#28]
Quote HistoryQuoted:
Because more and more people are opting for midlength barrels and there are more and more of them available. Increasing number of midlength builds and corresponding decrease in carbine builds = more midlength problems posted. For a 16" barrel, the midlength gas setup is a superior solution. Quote HistoryQuoted:
Quoted:
Understood, but why, then are there so many reported issues like this? Is gas block alignment so sensitive on mid length barrels? Seems not to be the case for barrels with carbine port location and typical port size, which is generous (perhaps overly so, but uber reliable) with most barrel makers. Because more and more people are opting for midlength barrels and there are more and more of them available. Increasing number of midlength builds and corresponding decrease in carbine builds = more midlength problems posted. For a 16" barrel, the midlength gas setup is a superior solution. I completely understand the theory and agree with it. But, it seems that it is not so clearly the case in actual practice. Even with 16" barrels with carbine gas ports, manufacturers were opening up the ports to .080" from .064" or so, to address the cycling issues with low power ammo. The complaints went away. So now, we move the port outward, lowering pressure all to supposedly make a low recoil rifle shoot softer, and, to no one's surprise, cycling problems emerge with low power ammo. And we call this progress. Maybe a case of, "well, it looked good on paper." |
|
|
|
Posted: 1/19/2017 2:02:32 PM EDT
[#29]
Quote HistoryQuoted:
I completely understand the theory and agree with it. But, it seems that it is not so clearly the case in actual practice. Even with 16" barrels with carbine gas ports, manufacturers were opening up the ports to .080" from .064" or so, to address the cycling issues with low power ammo. The complaints went away. So now, we move the port outward, lowering pressure all to supposedly make a low recoil rifle shoot softer, and, to no one's surprise, cycling problems emerge with low power ammo. And we call this progress. Maybe a case of, "well, it looked good on paper." Quote HistoryQuoted:
Quoted:
Quoted:
Understood, but why, then are there so many reported issues like this? Is gas block alignment so sensitive on mid length barrels? Seems not to be the case for barrels with carbine port location and typical port size, which is generous (perhaps overly so, but uber reliable) with most barrel makers. Because more and more people are opting for midlength barrels and there are more and more of them available. Increasing number of midlength builds and corresponding decrease in carbine builds = more midlength problems posted. For a 16" barrel, the midlength gas setup is a superior solution. I completely understand the theory and agree with it. But, it seems that it is not so clearly the case in actual practice. Even with 16" barrels with carbine gas ports, manufacturers were opening up the ports to .080" from .064" or so, to address the cycling issues with low power ammo. The complaints went away. So now, we move the port outward, lowering pressure all to supposedly make a low recoil rifle shoot softer, and, to no one's surprise, cycling problems emerge with low power ammo. And we call this progress. Maybe a case of, "well, it looked good on paper." That's an oversimplification of how the AR15 gas system works. What "looked good on paper" was what was done decades ago, of just extending the barrel while leaving the gas port in the same location and using a smaller gas port. This approach neglected the balance of pressures and forces that go into the operating cycle of the AR15. High pressures that are just fighting against each other is not how you have a well operating machine. |
|
|
|
Posted: 1/19/2017 11:23:05 PM EDT
[#30]
Quote HistoryQuoted:
That's an oversimplification of how the AR15 gas system works. What "looked good on paper" was what was done decades ago, of just extending the barrel while leaving the gas port in the same location and using a smaller gas port. This approach neglected the balance of pressures and forces that go into the operating cycle of the AR15. High pressures that are just fighting against each other is not how you have a well operating machine. Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
Understood, but why, then are there so many reported issues like this? Is gas block alignment so sensitive on mid length barrels? Seems not to be the case for barrels with carbine port location and typical port size, which is generous (perhaps overly so, but uber reliable) with most barrel makers. Because more and more people are opting for midlength barrels and there are more and more of them available. Increasing number of midlength builds and corresponding decrease in carbine builds = more midlength problems posted. For a 16" barrel, the midlength gas setup is a superior solution. I completely understand the theory and agree with it. But, it seems that it is not so clearly the case in actual practice. Even with 16" barrels with carbine gas ports, manufacturers were opening up the ports to .080" from .064" or so, to address the cycling issues with low power ammo. The complaints went away. So now, we move the port outward, lowering pressure all to supposedly make a low recoil rifle shoot softer, and, to no one's surprise, cycling problems emerge with low power ammo. And we call this progress. Maybe a case of, "well, it looked good on paper." That's an oversimplification of how the AR15 gas system works. What "looked good on paper" was what was done decades ago, of just extending the barrel while leaving the gas port in the same location and using a smaller gas port. This approach neglected the balance of pressures and forces that go into the operating cycle of the AR15. High pressures that are just fighting against each other is not how you have a well operating machine. But, it works and seems not to shorten rifle life appreciably while allowing the widest range of reliable ammo cycling. Scientifically, a bumble bee is not supposed to be able to fly, either. But, it does. On the other hand OP is having cycling issues that may (we are not yet sure) be attributable to the lower pressure of his middie barrel rather than gas block alignment. And he's not alone. |
|
|
|
Posted: 1/19/2017 11:50:53 PM EDT
[#31]
Quote HistoryQuoted:
OP, I would suggest you pull the front sight post off and confirm gas port hole is cleanly drilled and proper size in barrel and sight post. Also suggest you measure the location of gas hole from the step in the barrel, and measure the gas hole location in the front sight as well - confirm those measurements match. Dont trust the smith "done it right", anyone can make a mistake and could've overlooked bad parts (issue with gas ports). only way you will KNOW and be able to rule it out is to see for yourself. |
|
|
|
Posted: 1/20/2017 12:25:31 AM EDT
[#32]
Midlength is unreliable, sure
http://www.ar15.com/forums/t_2_138/196990_Filthy_14_is_now_over_40_000_rounds.html With the M4, i don't punch the tube/ clean the chamber on any of the guns (which are mostly BCM {midlength} now) link And yet again, where is the criticism of the KAC? |
|
|
|
Posted: 1/20/2017 2:29:34 AM EDT
[#33]
These things are pretty much infinitely tuneable so I don't think I would say either of them is less reliable than the other when setup right.
I think these pics show why the bushy carbine did not like the tula. What things do you guys think could be done to tune for it? What might happen on the other end when running hotter ammo? 
Tula gas port psi 
Wolf gas port psi 
|
|
|
|
Posted: 1/20/2017 2:53:35 AM EDT
[#34]
Quote HistoryQuoted:
I think these pics show why the bushy carbine did not like the tula. What things do you guys think could be done to tune for it? Use a gas system length with a larger operating envelope, and a correct gas port size. |
|
|
|
Posted: 1/20/2017 3:11:18 AM EDT
[#35]
That's cheating,
What, within reason, would you do to the bushy to run the tula? They say short stroking and failure to extract. I think my 1st stab would be a heavier buffer. 1. To let the gas port build more psi before it overcomes the additional mass and starts to move. 2. Once that additional mass gets moving, it will want to keep moving and move further back before the buffer spring stops it. 3. Should delay extraction, and maybe help that also. I don't know much about this stuff, but that is interesting data and prob good exercise. I am a little curious how the middy would have a larger operating envelope? |
|
|
|
Posted: 1/20/2017 3:24:40 AM EDT
[#36]
Quote HistoryQuoted:
What, within reason, would you do to the bushy to run the tula? Drill the gas port to a larger size to get more energy. You'll essentially be creating a Tula-only rifle, as you'd be severely over energy with most standard ammo and especially typical "5.56" power stuff. |
|
|
|
Posted: 1/20/2017 3:53:51 AM EDT
[#37]
Looking at how inconsistent the Tula is, you prob right.
No choice but to tune so that it will run on the small end, and get punished on the big end. Tula chamber psi 
You have a point in the right direction on what gives a middy a larger operating range than a carbine? I've had 2 Colts for ~20yrs (6724 and 6830). Understood the basics, but been playing with 80%'s lately and diving in a bit more. Latest one I am playing with is an an el cheapo grab bag middy. Cycle wise it blows the other two away in smoothness. Reliability is yet to be determined. I'm sure it will be better than that damn finicky x39 
|
|
|
|
Posted: 1/20/2017 4:06:51 AM EDT
[#38]
Here's nothing wrong with mid except that everyone with a pulse is now making AR parts.
|
|
|
|
Posted: 1/21/2017 4:53:38 PM EDT
[#39]
And everybody with hands is assembling every combination under the sun. Often with a perfect world mentality and no clue how these things actually work.
Building your own is a good way to learn wtf is going on in there, but it can be crash course. Luckily, most probs can be sorted with a little common sense. And worst of all, everybody with an asshole is posting crap on the interweb
|
|
|
|
Posted: 1/25/2017 6:22:16 PM EDT
[#40]
OP give us an update. Did ya get that thing lined out?
|
|
|
|
Posted: 1/27/2017 1:14:32 AM EDT
[#41]
Quote HistoryQuoted:
But, it works and seems not to shorten rifle life appreciably while allowing the widest range of reliable ammo cycling. Scientifically, a bumble bee is not supposed to be able to fly, either. But, it does. On the other hand OP is having cycling issues that may (we are not yet sure) be attributable to the lower pressure of his middie barrel rather than gas block alignment. And he's not alone. Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
Quoted:
Understood, but why, then are there so many reported issues like this? Is gas block alignment so sensitive on mid length barrels? Seems not to be the case for barrels with carbine port location and typical port size, which is generous (perhaps overly so, but uber reliable) with most barrel makers. Because more and more people are opting for midlength barrels and there are more and more of them available. Increasing number of midlength builds and corresponding decrease in carbine builds = more midlength problems posted. For a 16" barrel, the midlength gas setup is a superior solution. I completely understand the theory and agree with it. But, it seems that it is not so clearly the case in actual practice. Even with 16" barrels with carbine gas ports, manufacturers were opening up the ports to .080" from .064" or so, to address the cycling issues with low power ammo. The complaints went away. So now, we move the port outward, lowering pressure all to supposedly make a low recoil rifle shoot softer, and, to no one's surprise, cycling problems emerge with low power ammo. And we call this progress. Maybe a case of, "well, it looked good on paper." That's an oversimplification of how the AR15 gas system works. What "looked good on paper" was what was done decades ago, of just extending the barrel while leaving the gas port in the same location and using a smaller gas port. This approach neglected the balance of pressures and forces that go into the operating cycle of the AR15. High pressures that are just fighting against each other is not how you have a well operating machine. But, it works and seems not to shorten rifle life appreciably while allowing the widest range of reliable ammo cycling. Scientifically, a bumble bee is not supposed to be able to fly, either. But, it does. On the other hand OP is having cycling issues that may (we are not yet sure) be attributable to the lower pressure of his middie barrel rather than gas block alignment. And he's not alone. IF due to the gas system length lower than carbine port pressures are supposed to be a problem then the rifle length system should be the most troublesome yet it is the most reliable and least problematic. The mid length has been around and working exceedingly well for over 20 years, the rifle length for well over 50. I think it's safe to rule out gas system length as the root cause here. 
The majority of cycling issues reported have been in home builds. This was a common theme when the rifle system was number one in popularity. This theme was later repeated when the M4gery was the shizzle. The last 8 years both the mid length and home building have been in ascendancy of popularity so it's no surprise we are seeing a cycling issue in home builds theme again. Unless the barrel or gas block/FSB are are advertised specially as being for use without standard hand guard cap, the chances are excellent that the gas block/FSB is mis aligned front to back with the gas port. Setting the distance between the barrels GB/FSB shoulder and the GB/FSB to equal the thickness of a standard hand guard front cap usually resolves the issue. |
|
|
|
Posted: 1/27/2017 2:12:18 PM EDT
[#42]
Quote HistoryQuoted:
Buffer weight? This! what I was going to post. |
|
|
|
Posted: 2/5/2017 11:23:09 AM EDT
[#43]
Quoted:
The rifle started out as a Aero Precision AC-15, I changed out the barrel with a PSA mid length Freedom and a A1/C7 upper the lower has remained the same internally I just changed the stock to a retro CAR stock. While shooting I was using Mag Pul Gen 2 30 rd mags and on 4 separate occasions I had a failure to feed also failure to lock the bolt back after the last round. The ammo that I was using was Federal 55 gr AE and Remington 55 gr. What gives? When you changed the stock, did you use a different buffer tube, spring or buffer? After completing it, did you 'dry-cycle' the AR to check for smooth operation and full cycling movement? If it was found to be okay, did you do about 100 strokes on it - full pull and release? Right now, just pick it up, drop the mag, clear the chamber, pull the charging handle back and let it go forward slowly, checking for binding/stoppage. |
|
|
|
Posted: 2/7/2017 5:13:20 PM EDT
[#44]
Quote HistoryQuoted:
IF due to the gas system length lower than carbine port pressures are supposed to be a problem then the rifle length system should be the most troublesome yet it is the most reliable and least problematic. The mid length has been around and working exceedingly well for over 20 years, the rifle length for well over 50. I think it's safe to rule out gas system length as the root cause here. http://ar15barrels.com/tech/pressure-time.gif The majority of cycling issues reported have been in home builds. This was a common theme when the rifle system was number one in popularity. This theme was later repeated when the M4gery was the shizzle. The last 8 years both the mid length and home building have been in ascendancy of popularity so it's no surprise we are seeing a cycling issue in home builds theme again. Unless the barrel or gas block/FSB are are advertised specially as being for use without standard hand guard cap, the chances are excellent that the gas block/FSB is mis aligned front to back with the gas port. Setting the distance between the barrels GB/FSB shoulder and the GB/FSB to equal the thickness of a standard hand guard front cap usually resolves the issue. I don't debate the theory or the data, although the chart above has two very important limitations: 1: It is based on full power M193 NATO ammo and does not address low powered ammo and need to reliably cycle. 2: It does not address the very important issue of gas port diameter and the effect it has on reliable cycling. The problem remains, however that OP's midlength is undergassed. Being slightly overgassed is not a bad thing. It allows for a wider range of reliable ammo choices. I continue to be of the view that the rush to midlength has produced a rash of cycling issues with lower powered ammo. I only speculate, but it may be than many of these newer, budget midlength barrels are using too small gas port diameters. If they copied Colt's smaller gas port size rather than opening the port a bit more, this could explain the problem. Many manufacturers opened the port on 16" carbine barrels to around .080" to address this issue. Yes, they were a bit over gassed with NATO ammo, but they typically cycle everything. I'd love to know the actual gas port size on OP's PSA middie. If it is properly sized for a middie, then perhaps the gas block is misaligned. I'd not be surprised to see, however, that PSA used a too small port. |
|
|
|
Posted: 2/8/2017 12:16:35 AM EDT
[#45]
Factory middys are nothing new and have been running reliably with a wide variety of steel and brass .223 and 5.56 since the mid 90's. Assuming the gas tube and carrier are in order the only ways that the OP's rifle can be under gassed are either the wrong size gas port due to a defect in manufacture or gas block misalignment.
|
|
|
|
Posted: 2/27/2017 2:37:50 PM EDT
[#46]
Well I got the gas port on the barrel enlarged and now it runs everything I put through it.
The barrel is a PSA freedom pencil. |
|
|
|
Posted: 2/27/2017 2:43:50 PM EDT
[#47]
Quote HistoryQuoted:
Well I got the gas port on the barrel enlarged and now it runs everything I put through it. The barrel is a PSA freedom pencil. Enlarged to what? |
|
|
|
Posted: 2/27/2017 3:44:50 PM EDT
[#48]
Quote HistoryQuoted:
But, it works and seems not to shorten rifle life appreciably while allowing the widest range of reliable ammo cycling. Scientifically, a bumble bee is not supposed to be able to fly, either. But, it does. On the other hand OP is having cycling issues that may (we are not yet sure) be attributable to the lower pressure of his middie barrel rather than gas block alignment. And he's not alone. Scientifically, a bumble bee is quite flight worthy. What is inexplicable is why people feel the need to continue to insist that it isn't, or, that there is some inherent problem with the mid-length set-up. |
|
|
|
Posted: 2/27/2017 3:56:15 PM EDT
[#49]
Quote HistoryQuoted:
These things are pretty much infinitely tuneable so I don't think I would say either of them is less reliable than the other when setup right. I think these pics show why the bushy carbine did not like the tula. What things do you guys think could be done to tune for it? What might happen on the other end when running hotter ammo? http://labscdn2.luckygunner.com/labs/wp-content/uploads/2012/11/Gas-Port-Pressure-Sunday-e1357508948536.png Tula gas port psi http://labscdn2.luckygunner.com/labs/wp-content/uploads/2012/11/tulagp.jpg Wolf gas port psi http://labscdn2.luckygunner.com/labs/wp-content/uploads/2012/11/wolfgp.jpg Quote HistoryQuoted:
These things are pretty much infinitely tuneable so I don't think I would say either of them is less reliable than the other when setup right. I think these pics show why the bushy carbine did not like the tula. What things do you guys think could be done to tune for it? What might happen on the other end when running hotter ammo? http://labscdn2.luckygunner.com/labs/wp-content/uploads/2012/11/Gas-Port-Pressure-Sunday-e1357508948536.png Tula gas port psi http://labscdn2.luckygunner.com/labs/wp-content/uploads/2012/11/tulagp.jpg Wolf gas port psi http://labscdn2.luckygunner.com/labs/wp-content/uploads/2012/11/wolfgp.jpg Yet, a mid-length shot the majority of the low-powered Tula that the CLGS wouldn't run. A decision was made to fire the remainder of the Tula ammunition through other carbines. Approximately 300 rounds were fired through an HK416 (no malfunctions), 1,000 through a Spike’s Tactical carbine (3 malfunctions), and 6,000 through a Spike’s Tactical midlength without any cleaning (3 malfunctions). All malfunctions with the other carbines were stuck cases or failures to eject. So, with the low powered Tula the Bushmaster CLGS was so unreliable it had to dropped from the test, the Spikes CLGS had 333 MRBM (mean rounds between malfunctions), and the Spikes MLGS had 2000 MRBM. - W i d e r - o p e r a t i n g - e n v e l o p e - As was stated above. |
|
|
|
Posted: 2/27/2017 7:03:54 PM EDT
[#50]
It would be nice to know how much OP had to open up the gas port to get his midlength to shoot low powered ammo. Maybe he could pass that along. Original port diameter and new port diameter would be helpful.
|
|
|
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.
