Gunsmithing  AR issue need some advice

Altoonabcm157

Private
Minuteman
Oct 28, 2020
74
53
New jersey
I recently got a new ballistic advantage barrel for my ar. 18 inch spr profile rifle length gas system. I’m running a sprinco green rifle length buffer spring. I also have a superlative arms adjustable gas block. The issue I’m having is that when I fire it’s not picking up the next round. Ejection is fine but I have to run the charging handle every time I fire. I assume the issue is being under gassed. Any advice on a different gas block that could help the issue or is it worth having a smith open up the gas port on the barrel. Not sure what the solution is here any advice would be appreciated.
 
  • Like
Reactions: rottenruger

lone_soldier

Sergeant
Supporter
Full Member
Minuteman
Mar 15, 2007
792
61
34
lewistown, MT, Colorado
I have had 3 superlative arms adjustable gas blocks. If it is adjusted correctly therhould be no issue.
I and my buddies all have 12.5 and 18” Grendel’s. All with ballisticadvantage barrels and superlative arms gas blocks.

Not saying it’s impossible.... but 10/10 AR malfunctions are operator/assembler induced.

Tried multiple mags??
is the gas block all the way to one side? (Ran out of adjustment)

where is the ejection 1-6 o’clock?

is the gas block on straight?

is it tight?

what are the other component?

who put it together?

what ammo. What cartridge?

Need some more info.
 

FuhQ

Private
Full Member
Minuteman
  • Aug 26, 2013
    1,143
    697
    Alabama
    You're adjustable gas block needs to be opened up another notch... Stick a wrench in it, and open the port until it starts cycling correctly. Start with 1 notch, shoot one round, and see if it picks up the next. If not, open it up one more... Then repeat the process until it cycles properly and picks up the next round.

    If you have a 6-position collapsable stock, you should be running a milspec CARBINE-length spring & buffer, and not a rifle-length spring and buffer. Those are only for A1 and A2 style buttstocks. If that still doesn't help, you might need to slow down your BCG and put an H2 buffer in it.
     
    Last edited:

    FuhQ

    Private
    Full Member
    Minuteman
  • Aug 26, 2013
    1,143
    697
    Alabama
    I have had 3 superlative arms adjustable gas blocks. If it is adjusted correctly therhould be no issue.
    I and my buddies all have 12.5 and 18” Grendel’s. All with ballisticadvantage barrels and superlative arms gas blocks.

    Not saying it’s impossible.... but 10/10 AR malfunctions are operator/assembler induced.

    Tried multiple mags??
    is the gas block all the way to one side? (Ran out of adjustment)

    where is the ejection 1-6 o’clock?

    is the gas block on straight?

    is it tight?

    what are the other component?

    who put it together?

    what ammo. What cartridge?

    Need some more info.
    Also make sure the gas block is seated directly over the port (in-line with the set-screw indents, and NOT seated directly up against the barrel shoulder. There needs to be a tiny gap if you are using a free-floating handguard, and are NOT using an older Delta ring style handguard.
     

    Altoonabcm157

    Private
    Minuteman
    Oct 28, 2020
    74
    53
    New jersey
    I have a rifle length buffer a s buffer tube with an a2 stock so the spring is correct. The gas block is being run to allow the maximum amount of gas possible right now.
     

    Altoonabcm157

    Private
    Minuteman
    Oct 28, 2020
    74
    53
    New jersey
    I have had 3 superlative arms adjustable gas blocks. If it is adjusted correctly therhould be no issue.
    I and my buddies all have 12.5 and 18” Grendel’s. All with ballisticadvantage barrels and superlative arms gas blocks.

    Not saying it’s impossible.... but 10/10 AR malfunctions are operator/assembler induced.

    Tried multiple mags??
    is the gas block all the way to one side? (Ran out of adjustment)

    where is the ejection 1-6 o’clock?

    is the gas block on straight?

    is it tight?

    what are the other component?

    who put it together?

    what ammo. What cartridge?

    Need some more info.
    2 mags were used same result with both that’s all I had with me at the range.

    ejection is between 3 and 4 ovlock

    gas block appears to be installed correctly and is tight I will be checking the gas block later to make sure there are no alignment issues

    I put this together and is far from my first time so although it’s not impossible the chances of an installation issue is not highly likely

    I was firing federal xm193 range ammo
     
    • Like
    Reactions: lone_soldier

    6.5SH

    Major Hide Member
    Full Member
    Minuteman
    Jul 24, 2020
    2,096
    2,715
    Adequate lubrication? Being new and not broken in, you'd want more not less.
     
    • Like
    Reactions: larryh128

    Altoonabcm157

    Private
    Minuteman
    Oct 28, 2020
    74
    53
    New jersey
    It
    Adequate lubrication? Being new and not broken in, you'd want more not less.
    It was lubed before the range trip so I don’t think that is the issue here. This is my first 18 inch rifle length barrel and I know some have had gas port sizing issues with them so that was my first thought
     

    Lucreau

    Private
    Supporter
    Full Member
    Minuteman
    Oct 30, 2017
    550
    134
    CO
    Ballistic advantage has had their Fair share of barrels being sent back to be opened up. Did you use a dimple jig to simple your barrel for the GB to ensure its aligned properly? You could also ditch the sprinco spring for a standard a2 spring and a lighter buffer
     
    • Like
    Reactions: lone_soldier

    Altoonabcm157

    Private
    Minuteman
    Oct 28, 2020
    74
    53
    New jersey
    Ballistic advantage has had their Fair share of barrels being sent back to be opened up. Did you use a dimple jig to simple your barrel for the GB to ensure its aligned properly? You could also ditch the sprinco spring for a standard a2 spring and a lighter buffer
    I used a feeler guage to set the distance from the shoulder to the gas block, it is a clamp on gas block so I didn’t dimple the barrel. I could swap out the spring but to my understanding the green spring is standard strength
     

    Lucreau

    Private
    Supporter
    Full Member
    Minuteman
    Oct 30, 2017
    550
    134
    CO
    I used a feeler guage to set the distance from the shoulder to the gas block, it is a clamp on gas block so I didn’t dimple the barrel. I could swap out the spring but to my understanding the green spring is standard strength
    Ah gotcha. Yeah I think I would start with the gas block. And what weight buffer are you using?
     

    Lucreau

    Private
    Supporter
    Full Member
    Minuteman
    Oct 30, 2017
    550
    134
    CO
    And maybe try a non adjustable gas block to see how it shoots. Worst case shoot BA an e mail and see if they have any insight about the gas port size
     
    • Like
    Reactions: FuhQ

    hafejd30

    Supporter
    Supporter
    Full Member
    Minuteman
  • Feb 27, 2019
    2,270
    3,150
    MI
    If it still does it with the gas block opened up you could try a light weight carrier

    I ran a AGB and lightweight carrier in an AR for a while. 16” barrel. That thing was super smooth to shoot
     

    FuhQ

    Private
    Full Member
    Minuteman
  • Aug 26, 2013
    1,143
    697
    Alabama
    I used a feeler guage to set the distance from the shoulder to the gas block, it is a clamp on gas block so I didn’t dimple the barrel. I could swap out the spring but to my understanding the green spring is standard strength
    Yeah, I'd get a dimpling tool. Rainier Arms sells some really nice ones. I'd also get a GB drilling/pinning tool to ensure it doesn't slip around if the set-screws come loose.
     

    Simonsza1

    Private
    Full Member
    Minuteman
    Feb 27, 2014
    968
    534
    Just cause you set the block gap with a feeler gauge does not mean your gas port is lined up correctly. With a superlative open all the way and lined up perfectly with the gas hole in the barrel it would more then likely cycle all the way dispite the buffer used. Gas hole in barrel is typically plenty large and the block open all the way is plenty of gas. Need to make sure those two holes are cleanly aligned and your problem will go away. IMO
     

    Old Man with Gun

    Gunny Sergeant
    Full Member
    Minuteman
    Feb 4, 2019
    525
    679
    Just to be sure, have you turned the gas block all the way in the other direction and tried?
     

    sam4886

    Stunt Cock
    Full Member
    Minuteman
    May 15, 2019
    836
    478
    Eastern WA
    You're not into bleed off territory on the AGB are you? I forget the exact number, but I think like 14 clicks is full open with no gas bleed off, so full gas pressure.

    How does it cycle by hand, slowly? Feel any tight spots? When I break them in I dip the BCG in motor oil and blast a few mags through to really get everything running smooth. Then you can clean it off and get by with rem oil or whatever.
     
    • Like
    Reactions: Ravenworks

    Altoonabcm157

    Private
    Minuteman
    Oct 28, 2020
    74
    53
    New jersey
    I shoul
    You're not into bleed off territory on the AGB are you? I forget the exact number, but I think like 14 clicks is full open with no gas bleed off, so full gas pressure.

    How does it cycle by hand, slowly? Feel any tight spots? When I break them in I dip the BCG in motor oil and blast a few mags through to really get everything running smooth. Then you can clean it off and get by with rem oil or whatever.
    I shouldn’t be, I will have to double check superlative arms instructions but I’m pretty sure 4.5 turns is maximum pressure beyond that and you start to bleed off gas. I think it’s 18 clicks. Rifle cycles by hand fine, the upper was cerekoted so it’s possible that’s slowing things down alittle as well until it’s fully broken in.
     

    diggler1833

    World's Okayest Rancher and Hog Hunter
    Full Member
    Minuteman
  • Jul 22, 2007
    1,960
    5,281
    42
    Oklahoma
    While assembler error is usually the first suspect...it is never an absolute. I saw a post above that said it was 10/10 the builder's fault, and that is absolutely incorrect.

    I put together a large frame AR last year that gave me fits. My nitride coated (will never do that again) CMC gas tube was completely obstructed. Swapped that out and was short stroking still on a completely open and aligned gas block...went through everything. Finally checked the gas port on my Criterion barrel... .068" for a rifle length gassed, 18" .308. Opened it up to .093", and it's never missed a beat since. I had that upper fully apart three times. Burn rings around the ports were perfect...Swapped two buffers and springs...what a damn headache. I probably could have got away with just .020" increase, but an adjustable block is easier to screw with than drilling out a barrel a second time. By that point I was done with screwing around.

    I'm not saying that this is the reason the OP is having issues, it can be one of many things. However if EVERYTHING is properly aligned/installed, and you haven't checked the gas port size on your barrel its time to do so. If your gas tube is coated like it doesn't need to be, you might want to check flow through it too.
     
    • Like
    Reactions: Sniperstud

    chongoMT

    Sergeant
    Full Member
    Minuteman
    Jun 6, 2010
    412
    192
    Does the complete BCG work fine in a different upper? Is the gas key loose? Is there a verified pathway through the gas key into the carrier? Is the gas tube installed correctly and not upside down?
    I did not see these easy culprits in the above discussion.

    A loose/occluded gas key will present itself with some random problems.
     

    Altoonabcm157

    Private
    Minuteman
    Oct 28, 2020
    74
    53
    New jersey
    Does the complete BCG work fine in a different upper? Is the gas key loose? Is there a verified pathway through the gas key into the carrier? Is the gas tube installed correctly and not upside down?
    I did not see these easy culprits in the above discussion.

    A loose/occluded gas key will present itself with some random problems.
    Everything was properly installed, I tore it all apart and put it back together again, going back to the range tomorrow to see if I can get it running. If not I need to get some pin gauges and measure the gas port
     

    Mudburner

    Sergeant of the Hide
    Full Member
    Minuteman
    Apr 4, 2019
    160
    180
    I'm gonna throw this out there, because it puzzled me. Please allow me to offer a recent observation at the range.

    New buddy I met at the range said lets go shooting, so off we go. He has a 6.5 Grendel AR, and shot two different boxes of store-bought ammo. I dont know jack about 6.5, Grendel, and barely jack about ARs. But this is what happened:

    One variety of store bought ammo fired perfectly and cycled the rifle just fine, ejecting 4 or 5 feet at 2 o clock.

    The other ammo fired, but the rifle didnt pick up the next round and he had to hand cycle. Ejection for these rounds was about one foot at 4 or 5 o clock position.
    "Those first rounds are hotter," I observed, "these others wont cycle fully." hmmm, need more lube? Nah, plenty he says.

    He texted me next day from the range, saying his fix for the problem was to drill a hole in the buffer tube, and lube the buffer spring. I said what? He drilled a big hole in his buffer tube, supposedly allowing AIR PRESSURE to bleed off, because his opinion was that the buffer was acting like an air piston somehow had enough seal to hinder the cycling. I said I never heard anything like that before, but he says the lower pressure ammo now works great and problem solved... (I just shrug my shoulders and call him a jarhead.) Your thoughts?

    Is this even possible? For an AR buffer tube to be so airtight it actually compresses air & hinders cycling?
     

    Hateca

    Gunny Sergeant
    Full Member
    Minuteman
  • Aug 12, 2004
    1,566
    84
    Henderson NV
    I'm gonna throw this out there, because it puzzled me. Please allow me to offer a recent observation at the range.

    New buddy I met at the range said lets go shooting, so off we go. He has a 6.5 Grendel AR, and shot two different boxes of store-bought ammo. I dont know jack about 6.5, Grendel, and barely jack about ARs. But this is what happened:

    One variety of store bought ammo fired perfectly and cycled the rifle just fine, ejecting 4 or 5 feet at 2 o clock.

    The other ammo fired, but the rifle didnt pick up the next round and he had to hand cycle. Ejection for these rounds was about one foot at 4 or 5 o clock position.
    "Those first rounds are hotter," I observed, "these others wont cycle fully." hmmm, need more lube? Nah, plenty he says.

    He texted me next day from the range, saying his fix for the problem was to drill a hole in the buffer tube, and lube the buffer spring. I said what? He drilled a big hole in his buffer tube, supposedly allowing AIR PRESSURE to bleed off, because his opinion was that the buffer was acting like an air piston somehow had enough seal to hinder the cycling. I said I never heard anything like that before, but he says the lower pressure ammo now works great and problem solved... (I just shrug my shoulders and call him a jarhead.) Your thoughts?

    Is this even possible? For an AR buffer tube to be so airtight it actually compresses air & hinders cycling?

    Yes and yes. most mil spec buffer tubs have a hole drilled in the end to let out moisture and allow air to escape. Even the stock screw for an A2 stock has a hole drilled down the center. If you oil your buffer tube spring and shoot you will have a nice oil stain on your shirt from oil being pushed out that hole.
     

    mr45acp2u

    Private
    Full Member
    Minuteman
  • Sep 27, 2010
    117
    107
    AZ
    I don’t remember seeing the answer to this, have you tried another BCG? Was a the range a while back and one of the officers was having weird intermittent cycling issues. Primer made its way into the gas key. New BCG and no more issues.
     

    Altoonabcm157

    Private
    Minuteman
    Oct 28, 2020
    74
    53
    New jersey
    I don’t remember seeing the answer to this, have you tried another BCG? Was a the range a while back and one of the officers was having weird intermittent cycling issues. Primer made its way into the gas key. New BCG and no more issues.
    Same result with two different BCG’s and after reassembly of the gas block to the barrel. Now I’m in the process of ordering pin gauges to check gas port size
     

    BKKSW

    Private
    Full Member
    Minuteman
    Mar 2, 2017
    11
    4
    2 mags were used same result with both that’s all I had with me at the range.

    ejection is between 3 and 4 ovlock

    gas block appears to be installed correctly and is tight I will be checking the gas block later to make sure there are no alignment issues

    I put this together and is far from my first time so although it’s not impossible the chances of an installation issue is not highly likely

    I was firing federal xm193 range ammo
    After reading the entire thread I first second the idea of using a borescope to check gas block alignment and to adjust the AGB wide open as a starting point. Put enough AR's together and you'll have enough of these specific is issues causes by defective sized blocks, hairline cracks in blocks, etc, etc.. where it's just something you check every time. 2m during assembly on the bench can save hours of head scratching on the range.

    Next I'd try another BCG and all BCG related components including running a borescope of your buffer tube. I've gotten A LOT of really poorly machined buffer tubes and if there are ridges on the interior it can slow down your system.

    And then ammo. Wouldn't be the first or hundredth both of XM193 that wasn't right.

    Good luck.
     

    chongoMT

    Sergeant
    Full Member
    Minuteman
    Jun 6, 2010
    412
    192
    Same result with two different BCG’s and after reassembly of the gas block to the barrel. Now I’m in the process of ordering pin gauges to check gas port size

    The pin gauges won't help you much at this point. What are you going to do with the information? As long as there is a port hole in the barrel close to the appropriate size you should be tuning things to function with that adj gas block. Almost every suggestions by folks here seems to have been tried or n/a to your issue,
    Save the $ on gauges and send the upper to a gunsmith.
     

    rottenruger

    Sergeant of the Hide
    Full Member
    Minuteman
    May 31, 2020
    299
    128
    I recently got a new ballistic advantage barrel for my ar. 18 inch spr profile rifle length gas system. I’m running a sprinco green rifle length buffer spring. I also have a superlative arms adjustable gas block. The issue I’m having is that when I fire it’s not picking up the next round. Ejection is fine but I have to run the charging handle every time I fire. I assume the issue is being under gassed. Any advice on a different gas block that could help the issue or is it worth having a smith open up the gas port on the barrel. Not sure what the solution is here any advice would be appreciated.
    Not as knowledgeable but had a similar sounding problem with an old SKS I bought. Tried cleaning the gas tube, fiddling with the grenade launcher attachment that was completely foreign to me, nothing worked. Gave up and took it to my smith who was way behind on orders.

    About 6 weeks later he called and said it was ready........turned out to be the magazines were hanging the rounds........he filed down the three mags I had, and happy days are here again! Hope your problem might be similarly easy!
     

    SilencedShooter11B

    Private
    Minuteman
    Aug 1, 2013
    81
    60
    Lexington, SC
    Hmm, wow. Appreciate ya! Learned something new.

    Only if you’re using a stock that exposes the end of the buffer tube. I put a light coat of lube on my spring and obviously storing rifles muzzle up in the safe, gravity pulls any excess down there. No issues with oil covered shirts. If it’s a concern, take a 7.62cal bore patch and put it in the bottom of the tube to soak up any oil and put the spring in. The cotton will allow air to escape while still soaking up any lubricants.

    The pin gauges won't help you much at this point. What are you going to do with the information? As long as there is a port hole in the barrel close to the appropriate size you should be tuning things to function with that adj gas block. Almost every suggestions by folks here seems to have been tried or n/a to your issue,
    Save the $ on gauges and send the upper to a gunsmith.

    Recently assembled a 6ARC using a barrel from a highly respected source and brand. Was having the same issue and it was definitely under gassed (24” rifle +2” from the manufacturer with a .080” port. Another member here with a barrel from the same place was having the exact same issue around the same time) Opened the port up to .093” and it runs like a champ now.

    Being able to pin the gas port would possibly give him some info...whether or not it’s a potential source of the problem. Could’ve been incorrectly sized at the factory, but if it’s “in range” then the info isn’t the end all be all answer but it’s more information that can be used to pin point it

    But you are right, sending it to a smith who can diagnose it and already has the tools to do so, as well as the tools to remedy it can save a lot of headaches
     
    Last edited:

    Altoonabcm157

    Private
    Minuteman
    Oct 28, 2020
    74
    53
    New jersey
    The pin gauges won't help you much at this point. What are you going to do with the information? As long as there is a port hole in the barrel close to the appropriate size you should be tuning things to function with that adj gas block. Almost every suggestions by folks here seems to have been tried or n/a to your issue,
    Save the $ on gauges and send the upper to a gunsmith.
    They are going to determine if the port is undersized and the manufacturer should make this right on their dollar or if I need to pay a gunsmith to do work on the rifle.
     

    Simonsza1

    Private
    Full Member
    Minuteman
    Feb 27, 2014
    968
    534
    Having any firearm that doesn’t work is not appealing! If you don’t have the knowledge And are relying on the hide for the answer then it may be worth having it done correctly. You may have the knowledge idk, I’m not calling you out just saying sometimes it’s best to get a professional to cure the issue for something you may need to save your life one day.
     

    hafejd30

    Supporter
    Supporter
    Full Member
    Minuteman
  • Feb 27, 2019
    2,270
    3,150
    MI
    If the gun won’t run with gas block fully open my suggestion is try the lightest buffer/spring combo and get a lighter carrier. Try a AR 15 carrier first then get a lightweight carrier if that doesn’t work. You can always close the gas block more to accommodate the new parts.

    If that doesn’t work then you have other issues

    Possibly try other mags (I know you mentioned trying 2 but make sure you try another brand)

    What does the rifle feel like? I had a mag issue a couple weeks ago. A gun that runs flawlessly all the sudden won’t lock back on the empty mag. I cleaned the rifle, same result. Then turned my bootleg carrier wide open. Same issue but noticeable recoil beating the gun up.

    Turned out to be the mag. But was confused for a bit. Every other mag runs flawlessly with prior setting. Magpul pmags
     

    coyotewillie

    Private
    Full Member
    Minuteman
    Oct 5, 2005
    268
    104
    67
    NE
    A set of pin gauges would be nice to have. But a good set of number drill bits will do the same. And you always need drill bits!
     

    vinniedelpino

    Guns and Butter
    Full Member
    Minuteman
  • Sep 27, 2020
    1,093
    1,577
    Charlotte NC
    Any chance the gas tube is rubbing against the inside of the carrier key?

    Does the bcg drop right into place with upper off and muzzle pointed to the floor? Or is there resistance?
     

    jeffpatton00

    Private
    Minuteman
    Mar 31, 2017
    19
    2
    I recently got a new ballistic advantage barrel for my ar. 18 inch spr profile rifle length gas system. I’m running a sprinco green rifle length buffer spring. I also have a superlative arms adjustable gas block. The issue I’m having is that when I fire it’s not picking up the next round. Ejection is fine but I have to run the charging handle every time I fire. I assume the issue is being under gassed. Any advice on a different gas block that could help the issue or is it worth having a smith open up the gas port on the barrel. Not sure what the solution is here any advice would be appreciated.
    A simple question, similar to a Helpdesk tech asking if the computer is plugged in - do you have a rifle-length buttstock, buffer and buffer tube? Not advised to mix rifle length barrel & gas tube with carbine length buttstock. Not that you're doing this, of course, but worth mentioning none the less.