Gas gun barrel issues?

Sako man

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  • Sep 7, 2012
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    Galactic Sector ZZ9 Alpha Xray Plural.
    I am wondering if anyone has seen this kind of pitting in your barrel, and what causes it? Shooting a gas gun I just picked up and it's really not printing groups that well.



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    "Not printing groups that well"

    Have you contacted the manufacturer/retailer for a potential warranty issue? Or is this an "as is" buy off the PX?

    What ammo?

    Russian steel case 55gr/plinking reloads vs Federal 69gr Gold Medal Match/finalized known accuracy load proven in multiple rifles.

    What's the purpose of that rifle?

    Fun/blasting vs. DMR/precision-ish.

    If it doesn't measure up to the purpose standards you "need" it for, toss it and get another barrel, or relegate it to the "plinking rifle" category.
     
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    "Not printing groups that well"

    Have you contacted the manufacturer/retailer for a potential warranty issue? Or is this an "as is" buy off the PX?

    What ammo?

    Russian steel case 55gr/plinking reloads vs Federal 69gr Gold Medal Match/finalized known accuracy load proven in multiple rifles.

    What's the purpose of that rifle?

    Fun/blasting vs. DMR/precision-ish.

    If it doesn't measure up to the purpose standards you "need" it for, toss it and get another barrel, or relegate it to the "plinking rifle" category.
    I got it off the PX here. Seller said its a Bergara barrel. And it's on a mk12 clone. Seller said only 250 rounds through it. I put some 77 fgmm through it. No, this needs to be in precision land for me.
     
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    Before we go down the rabbit hole:
    (1) Define "printing groups well" Are we talking 2" and you expect 1"? 1" and you expect 0.25"
    (2) For the crowd: how much can whatever 'that' is in the picture affect accuracy.
    (3) What is "low" MV. What round and what load. Details man!
     
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    Before we go down the rabbit hole:
    (1) Define "printing groups well" Are we talking 2" and you expect 1"? 1" and you expect 0.25"
    (2) For the crowd: how much can whatever 'that' is in the picture affect accuracy.
    (3) What is "low" MV. What round and what load. Details man!
    Needs to hold 1 MOA. Shooting 1.5 to 2 right now. And MV around 2500. Pretty low MV for an 18" barrel.

    My 16" criterion barrel shoots the same ammo at 2790 and maintains under 1 MOA

    I scrubbed it out with KG and going to re shoot it and see. It might just be shot and need a new barrel. Will find out.
     
    This isn't a casting

    The odds that wrought bar stock would have that many inclusions are simply astronomically low.

    99% sure those are corrosion pits. And before anyone says "but it's stainless", 416 will absolutely rust. Just not as quickly as carbon steels.
    You should send him one of your barrels then an let him try it out. You're manufacturing and sales should take way off. I;m sure there's no possible way all those pits exist in that steel. Even the pictures must be wrong. Nobody ever makes bad steel.
     
    You should send him one of your barrels then an let him try it out. You're manufacturing and sales should take way off. I;m sure there's no possible way all those pits exist in that steel. Even the pictures must be wrong. Nobody ever makes bad steel.
    What are your qualifications to support your claims?
     
    You'll have to decide at which point your time is worth more than a new barrel. I'd shoot it and see if it settles. But if by 200-250 rounds it hasn't, time to buy it's replacement. JMO.
    Right here. ^^^I am obviously not the metallurgist you are. I mean the pictures show pitted metal, but that can't possibly be the case because you've never seen it before and it's highly unlikely that it exists. But feel free to explain how 416 goes that south after 250 rounds. I'm all ears.
     

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    Right here. ^^^I am obviously not the metallurgist you are. I mean the pictures show pitted metal, but that can't possibly be the case because you've never seen it before and it's highly unlikely that it exists. But feel free to explain how 416 goes that south after 250 rounds. I'm all ears.
    Corrosion doesn't care about round count. Time is the enemy
     
    Right here. ^^^I am obviously not the metallurgist you are. I mean the pictures show pitted metal, but that can't possibly be the case because you've never seen it before and it's highly unlikely that it exists. But feel free to explain how 416 goes that south after 250 rounds. I'm all ears.
    Stainless will and does rust,the process can be helped along by using the improper (cheap steel) brush.
     
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    Have you tried any other ammo, perhaps FGMM 69gr or FGMM 73gr?

    What's the throat look like? Looks pretty new or does it look like someone mag dumped the hell outta it?
     
    Have you tried any other ammo, perhaps FGMM 69gr or FGMM 73gr?

    What's the throat look like? Looks pretty new or does it look like someone mag dumped the hell outta it?
    The throat was caked with carbon, easy clean. But once I got through it there is a lot of cracking in the stele. So yeah..... I wouldn't call it mag dumb, but rather higher than stated round count.

    Yes, I shot freedom munitions 75gr and IMI 77 grain, all MV's are lower then in my other rifles.

    Ordered a new barrel, at this point I don't have the time to chase things. But it kinda sucks as I don't believe this was as stated. I could totally be wrong but I really don't think so.
     
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    I got it off the PX here. Seller said its a Bergara barrel. And it's on a mk12 clone. Seller said only 250 rounds through it. I put some 77 fgmm through it. No, this needs to be in precision land for me.
    Bergara is not known for producing good ar barrels. Do you mk12 right and order a Douglas barrel from CLE or WOA
     
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    I got it off the PX here. Seller said its a Bergara barrel. And it's on a mk12 clone. Seller said only 250 rounds through it. I put some 77 fgmm through it. No, this needs to be in precision land for me.

    There's probably nothing wrong with it per se you are getting what you paid for. Muzzle velocity of 2600-2650 and 1-1.5MOA groups would be my guess?

    If you want it to be "precision" then spend more money. White Oak are the cheapest ones that still perform fairly well MOA or better. Otherwise get a Douglas which is the spec.
     
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    How quickly does this carbon holding moisture and then damaging your barrel process take? The idea of having to DEEP clean my barrel down to the steel everytime I go to the range sounds awful. We talking a month, a year? Now you got me all worried over here lol
     
    Too many variables to predict that. Are you storing them in a safe, inside a padded foam case, Florida humidity or Arizona desert, etc.

    Simple preventative maintenance is to run a dry patch to remove loose carbon and then a wet oil patch down the barrel at the end of the range trip. Run a dry patch down the barrel before the start of one.
     
    There's probably nothing wrong with it per se you are getting what you paid for. Muzzle velocity of 2600-2650 and 1-1.5MOA groups would be my guess?

    If you want it to be "precision" then spend more money. White Oak are the cheapest ones that still perform fairly well MOA or better. Otherwise get a Douglas which is the spec.
    There's probably nothing wrong with it per se you are getting what you paid for. Muzzle velocity of 2600-2650 and 1-1.5MOA groups would be my guess?

    If you want it to be "precision" then spend more money. White Oak are the cheapest ones that still perform fairly well MOA or better. Otherwise get a Douglas which is the spec.
    The accuracy is ok, 1.5 moa being smallest groups, most about 2 moa. I would like to get it to 1moa. But the MV is way too low, 2500... that's with FGMM, the other stuff I'm shooting is hovering around 2550. Doubt it would stay transonic for long.

    I got a new barrel coming. PRI has been closed so looking for instructions to remove the hand guard.
     
    The accuracy is ok, 1.5 moa being smallest groups, most about 2 moa. I would like to get it to 1moa. But the MV is way too low, 2500... that's with FGMM, the other stuff I'm shooting is hovering around 2550. Doubt it would stay transonic for long.

    I got a new barrel coming. PRI has been closed so looking for instructions to remove the hand guard.

    What handguard? The carbon fiber tube thingy is a lock ring at one end you just unscrew it with a spanner wrench or strap wrench or whatever.
     
    What handguard? The carbon fiber tube thingy is a lock ring at one end you just unscrew it with a spanner wrench or strap wrench or whatever.
    It's the Gen1 carbon SPR handguard, the early one. Has some tiny nuts on it... ok, there's a joke in there somewhere. It's a little tricky as there is that top rail. I have to look at it closer. A friend did get me the PRI site that covers some of this.

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    Last edited:
    Looks like its still a lock ring design but with a diff barrel nut than I remember



    Maybe there's a couple allens inside it for set screws or something but I bet it just unscrews.

    Is that gas block pinned on? When I had one it was a clamp I think. If it's pinned you'll have to bonk those out too.
     
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    Looks like its still a lock ring design but with a diff barrel nut than I remember


    Is that gas block pinned on? When I had one it was a clamp I think. If it's pinned you'll have to bonk those out too.
    The gas block just as the set screws, thankfully. Yes there's some tiny allen screws. Is the handguard attached to that top rail or are they both separate? If detached perhaps I don't have to monkey with it.