Success with getting 9" Barrels to run
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Thread: Success with getting 9" Barrels to run

  1. #1
    XCR Guru aziator's Avatar
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    Success with getting 9" Barrels to run

    *Disclaimer*

    I am not sure if any of this will void your warranty, proceed at your own risk. My goal was to be able to fully use the rifle and if it only cycles on setting #4 that defeats the purpose of the other settings. I want the option of turning up the gas if it needs it.

    **End Disclaimer**

    For those that might not have read any of the other threads, I had both a 7.62x39 and a 5.56 barrel in 9" that didn't want to run 100%. I will start with the 7.62x39

    The 7.62x39 barrel shot brown bear and wolf no problem on setting 4. Anything under that it would short stroke or even fail to eject. I have some brass cased surplus ammo that wouldn't even hardly chamber, let along feed. It seemed like every time I chambered a round I would have to Pogo the gun to get the round out when it didn't seat all the way. I took it as a 3 step process.

    1. Flex honed the chamber using 800 grit .308 flex hone. This completely smoothed out the chamber and allowed all ammo to easily chamber.

    2. Opened up the gas port on the barrel. I have a pretty nice Snap-On drill bit set, has tons of sizes. I started with a bit that was just a little bigger than factory and went up one size. I did this a couple times at the range and got it to where every type ammo would run on setting 4. I still couldn't get anything to run on 3.

    3. I took the barrel off ans pulled the gas block. I figured if the gas block and gas port in the barrel were the same that would make the most sense. I started with the gas block and opened it up with a 5/32" bit. It only ended up being slightly bigger than stock. Next I went to the gas dial. On this one I opened up #4 to 5/32" and left everything else alone. On the barrel I opened it up to 5/32".

    4. Went and shot it at the range. I started with brown bear, which had always been reliable. I shot on 4, no problems. Went to 3, no problems, still throwing brass 10-13 feet. Setting 2 throws it between 5-10 feet and setting one was about 3 feet with failure to lock back on the last round. I tired the brass cased surplus stuff and it was the same on 4 and 3 but 2 was iffy. I am happy leaving it on 3 for that ammo.

    Recoil didn't feel any different and the gun didn't feel like it was over-gassed.

    Now on to the 5.56 barrel. This one was horrible, wouldn't chamber ANYTHING.

    1. Flex hones the barrel. I started with the 400 grit then did the 800 grit. This completely eliminated the chambering problems. The rifle would cycle most of the time on setting 4 but wasn't 100%.

    2. Barrel and gas block/dial enlargement. I enlarged the Gas block up to 9/64". The gas dial needed a little work, it looked like 1-3 were the exact same size. I started with #4 and made it 9/64". #3 went to 3/32", #2 is now 5/64" and #1 is 1/16th". Now I had a truly adjustable gas dial.
    The gas hole in the barrel was between 1/16" and 5/64", real tiny. I bumped that up to 3/32.

    4. Range trip showed excellent results. I was able to now shoot my reloads that wouldn't even chamber before. The great part is I was able to reliable run my reloads on setting #1. When I tried Wolf I had similar results, able to reliably cycle (brass ejecting around 8 feet and locking back after the last round) all on setting 2.

    Overall, I am very happy with the results. Every rifle is different and some might not require everything I did. The key is to do it in steps from least evasive to most.
    Don't confuse enthusiasm for competence

    Want more grip for your M&P Pistol? Send me a message.

  2. #2
    DSM
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    Re: Success with getting 9" Barrels to run

    Good to hear!
    When have any of our plans ever actually worked? We plan, we get there, all hell breaks loose.

  3. #3
    Expert Carpenter's Avatar
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    Re: Success with getting 9" Barrels to run

    Yeah, thats very cool. 8)
    hope for the best, prepare for the worst, and make hay while the sun shines!

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  5. #4
    XCR Guru Sean K.'s Avatar
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    Re: Success with getting 9" Barrels to run

    Chris....just keep an eye on the buffer. If you go too big on one of the ports, the buffer will be the first thing to tell you to turn the gas down.

    Congrats....you did what I ended up doing on my 10.5" to a large degree. Alex told me I could open the gas port as big as I wanted and it still wouldn't run. Obviously, you and I have both found out differently.

    Sean
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

  6. #5
    XCR Guru aziator's Avatar
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    Re: Success with getting 9" Barrels to run

    Quote Originally Posted by Sean K. View Post
    Chris....just keep an eye on the buffer. If you go too big on one of the ports, the buffer will be the first thing to tell you to turn the gas down.

    Congrats....you did what I ended up doing on my 10.5" to a large degree. Alex told me I could open the gas port as big as I wanted and it still wouldn't run. Obviously, you and I have both found out differently.

    Sean
    My 11" 5.56 barrel with the full length upper doesn't do well unsuppressed on anything but 4. I think I am going to open it a touch and see how it does.
    Don't confuse enthusiasm for competence

    Want more grip for your M&P Pistol? Send me a message.

  7. #6
    XCR Guru dont_tread_on_me's Avatar
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    Re: Success with getting 9" Barrels to run

    Chris this is excellent news.It's really good to hear someone doing this kind of stuff themselves and getting good results.This confirms my theories about tight chambers from some time ago.If the chrome lining is rough or inconsistent,it's no wonder why an expanded case is hard to get out of the chamber.It also firmly illustrates how you need to have enough gas in the system for proper extraction and timing.



    War is an ugly thing, but not the ugliest of things: the decayed and degraded state of moral and patriotic feeling which thinks nothing worth a war, is worse.... A man who has nothing which he is willing to fight for, nothing which he cares more about than he does about his personal safety, is a miserable creature who has no chance of being free, unless made and kept so by the exertions of better men than himself.----John Stuart Mill

  8. #7
    XCR Guru Sean K.'s Avatar
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    Re: Success with getting 9" Barrels to run

    Chris....

    Please keep me updated....especially regarding your buffer wear (if you notice any increase).

    MY 10.5" is running Brown Bear on 3......but I'd like to see the 10.5" be able to cycle Wolf Black Box on 3 as well. I've thought about opening the gas block (factory spec is .136") and even going larger on the bbl port (I'm at .0995 IIRC) and possibly opening the gas dial up some too....but don't want to go too far with it.

    I need to go back over your post b/c some of the numbers you posted are way out of spec for a 9" 5.56 bbl....at least according to RA's spec.

    Sean
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

  9. #8
    XCR Guru Sean K.'s Avatar
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    Re: Success with getting 9" Barrels to run

    Quote Originally Posted by aziator View Post
    *Disclaimer*

    I am not sure if any of this will void your warranty, proceed at your own risk. My goal was to be able to fully use the rifle and if it only cycles on setting #4 that defeats the purpose of the other settings. I want the option of turning up the gas if it needs it.

    **End Disclaimer**

    For those that might not have read any of the other threads, I had both a 7.62x39 and a 5.56 barrel in 9" that didn't want to run 100%. I will start with the 7.62x39

    The 7.62x39 barrel shot brown bear and wolf no problem on setting 4. Anything under that it would short stroke or even fail to eject. I have some brass cased surplus ammo that wouldn't even hardly chamber, let along feed. It seemed like every time I chambered a round I would have to Pogo the gun to get the round out when it didn't seat all the way. I took it as a 3 step process.

    1. Flex honed the chamber using 800 grit .308 flex hone. This completely smoothed out the chamber and allowed all ammo to easily chamber.

    2. Opened up the gas port on the barrel. I have a pretty nice Snap-On drill bit set, has tons of sizes. I started with a bit that was just a little bigger than factory and went up one size. I did this a couple times at the range and got it to where every type ammo would run on setting 4. I still couldn't get anything to run on 3.

    3. I took the barrel off ans pulled the gas block. I figured if the gas block and gas port in the barrel were the same that would make the most sense. I started with the gas block and opened it up with a 5/32" bit. It only ended up being slightly bigger than stock. Next I went to the gas dial. On this one I opened up #4 to 5/32" and left everything else alone. On the barrel I opened it up to 5/32".

    4. Went and shot it at the range. I started with brown bear, which had always been reliable. I shot on 4, no problems. Went to 3, no problems, still throwing brass 10-13 feet. Setting 2 throws it between 5-10 feet and setting one was about 3 feet with failure to lock back on the last round. I tired the brass cased surplus stuff and it was the same on 4 and 3 but 2 was iffy. I am happy leaving it on 3 for that ammo.

    Recoil didn't feel any different and the gun didn't feel like it was over-gassed.

    Now on to the 5.56 barrel. This one was horrible, wouldn't chamber ANYTHING.

    1. Flex hones the barrel. I started with the 400 grit then did the 800 grit. This completely eliminated the chambering problems. The rifle would cycle most of the time on setting 4 but wasn't 100%.

    2. Barrel and gas block/dial enlargement. I enlarged the Gas block up to 9/64". The gas dial needed a little work, it looked like 1-3 were the exact same size. I started with #4 and made it 9/64". #3 went to 3/32", #2 is now 5/64" and #1 is 1/16th". Now I had a truly adjustable gas dial.
    The gas hole in the barrel was between 1/16" and 5/64", real tiny. I bumped that up to 3/32.

    4. Range trip showed excellent results. I was able to now shoot my reloads that wouldn't even chamber before. The great part is I was able to reliable run my reloads on setting #1. When I tried Wolf I had similar results, able to reliably cycle (brass ejecting around 8 feet and locking back after the last round) all on setting 2.

    Overall, I am very happy with the results. Every rifle is different and some might not require everything I did. The key is to do it in steps from least evasive to most.
    So, on your 5.56.....the bbl port was less than 5/64"....which is .078125". Even if you're measuring with just a drill bit and not a precise gauge pin set....that tells me the port was WAAY off to begin with. The 9" 5.56 PDW bbl was supposed to have a factory .086" port.

    I'm going to make some notes here just for ease of future reference for myself if I do size up some of my ports. I have a machinist drill bit set so everything's in decimals.

    ***ETA*** The numbers below are what Chris (Aziator) did to HIS gun....they are NOT the factory specs.

    9/64=.140625" (5.56 gas block and #4 dial position)

    3/32=.09375" (5.56 bbl port and #3 dial position)

    5/64=.078125 (5.56 #2 dial position)

    1/16=.0625" (5.56 #1 dial position)

    So essentially, the smallest 'port' the gas goes through (with the gas set on 4) in your gun is the bbl port at .09375" .

    Flow through should be the same on 3, assuming (and this is a big ASSumption) that your gas block lines up PERFECTLY with your bbl port (none of mine have but they are all close enough to work). It's only when you get down to setting 2 or 1 that you run into restriction.

    Interesting....Thanks much for the info and exact sizes you're using. I'd like to tinker with mine some more, but at this point I'm out of money to buy ammo for the experiment.

    Sean
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

  10. #9
    XCR Guru aziator's Avatar
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    Re: Success with getting 9" Barrels to run

    I just pulled my 10.3" Daniel Defense barrel out and it has a gas port size of about .09" (which is about what I remember them saying it was opened up to so that it would run). That gun runs all day (never tried anything but brass case). I know it is an AR and slightly different.

    I will keep you updated on the buffer. The wolf that I was shooting was from a black box. I don't normally shoot the stuff but I wanted to try it for testing. It looked like a polymer gray colored steel case. Running on 2 is good by me.

    If you still have the 9" I would recommend playing with that one.
    Don't confuse enthusiasm for competence

    Want more grip for your M&P Pistol? Send me a message.

  11. #10
    XCR Guru WatchoutforStobor's Avatar
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    Re: Success with getting 9" Barrels to run

    Quote Originally Posted by Sean K. View Post
    So, on your 5.56.....the bbl port was less than 5/64"....which is .078125". Even if you're measuring with just a drill bit and not a precise gauge pin set....that tells me the port was WAAY off to begin with. The 9" 5.56 PDW bbl was supposed to have a factory .086" port.

    I'm going to make some notes here just for ease of future reference for myself if I do size up some of my ports. I have a machinist drill bit set so everything's in decimals.

    9/64=.140625" (5.56 gas block and #4 dial position)

    3/32=.09375" (5.56 bbl port and #3 dial position)

    5/64=.078125 (5.56 #2 dial position)

    1/16=.0625" (5.56 #1 dial position)

    So essentially, the smallest 'port' the gas goes through (with the gas set on 4) in your gun is the bbl port at .09375" .

    Flow through should be the same on 3, assuming (and this is a big ASSumption) that your gas block lines up PERFECTLY with your bbl port (none of mine have but they are all close enough to work). It's only when you get down to setting 2 or 1 that you run into restriction.

    Interesting....Thanks much for the info and exact sizes you're using. I'd like to tinker with mine some more, but at this point I'm out of money to buy ammo for the experiment.

    Sean



    Sean, thanks for the info. You don't happen to have the specs for the 16" 5.56 barrel and gas plug?







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