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Arc Nuclues action owners

Schw15

Longrange
Full Member
Minuteman
  • Jul 21, 2019
    4,359
    1,063
    Colorado
    Posted a video of my action. Easy bolt lift then at the top it snaps open pretty hard. I talk to ARC said that was normal not saying I don't believe them or question them at all just seeing if anyone else has that samething with these actions? I'm more or less just curious.

    Arc Nucleus Gen 2 long action mag bolt face. 30 nosler but get samething on other calibers.

    My loads show no sign of pressure with primers ect. My speeds are pretty dang slow in a 30 inch barrel for that not to happen just figured I'd throw that out there since it was going to be brought up.

    Once again just more or less curious if others see this with those actions across the board.
     
    It sounds like the brass dragging in the chamber and it then engaging the primary extraction ramp and not the action itself to me.
     
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    Cases are sticking in the chamber and you're having to engage the primary extraction cam. It's a case/pressure/chamber thing not the action.
     
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    I was thinking maybe the dies wasn't resizing the case enough at case head with .002 shoulder bum. Pressure not much there no signs in primer or no heavy bolt lift. I can open bolt easy to the top. My speeds are in the 2860 to 2900 for 230 a-tips 30 nosler and 30 inch barrel.

    But send videos to ARC they said it was nor.al but just wanted to see others experiences
     
    Hi Scott,

    The hang-up at the top does seem to be a normal function of the action when brass is stuck in the chamber. The Nucleus uses bolt-cam extraction, so what is happening is that when you are getting near the top of the bolt lift, the handle of the bolt is hitting the angled surface at the back of the receiver to simultaneously pull the bolt open and back to get the case out. Please let me know if you have any other questions.

    Thank you,

    From ARC
     
    How hot is your load? :|
     
    Clickers either need new dies custom dies or polish out chamber maybe I guess. Ran into this twice the past few years before that the last 15 years nothing like this
     
    Consider ordering a die from Whidden or better yet if you have time send them fired brass and have them make you a custom sizing die. Their standard die will most likely fix your issue.
     
    Mine does it sometimes but has gotten better. Seemed to to it worse on new brass than fired a couple times.

    I thought initially is was pressure but my loads in that rifle are not near the top end so I kinda forgot about it.
     
    Consider ordering a die from Whidden or better yet if you have time send them fired brass and have them make you a custom sizing die. Their standard die will most likely fix your issue.
    They don't make a 30 nosler die have to be custom
     
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    Mine does it sometimes but has gotten better. Seemed to to it worse on new brass than fired a couple times.

    I thought initially is was pressure but my loads in that rifle are not near the top end so I kinda forgot about it.
    So yours does that all the time as well?
     
    So yours does that all the time as well?
    Not anymore. Prob have 500 rounds on the action now with 3 different barrels for it. It probably hasn't done it in the last 200-300 rounds.
     
    Not anymore. Prob have 500 rounds on the action now with 3 different barrels for it. It probably hasn't done it in the last 200-300 rounds.
    Strange. Mine has prolly 2k or more on it. Mine does it more when the brass gets older
     
    Strange. Mine has prolly 2k or more on it. Mine does it more when the brass gets older
    As expected. It’s a vivacious cycle.
    The older the brass gets the more it has been fired and sized.
    The more it gets fired and sized the harder it gets as a result of the work done to it.
    The harder it gets the more it wants to spring back opposite to sizing so it won’t get smaller and it will get larger while resisting the sizing die.
    So you need to find a die that sizes down more still to overcome the spring back or you need to open the chamber a smidge to allow your current die to be enough sizing that it springs back away from the chamber after firing towards its sized state.
    Sounds like right now it’s more tangential contact between the die and the brass coming out of it but some dimensional numbers for the brass sized-loaded-fired for each cycle of its life would be helpful in tracking this sort of issue.
     
    As expected. It’s a vivacious cycle.
    The older the brass gets the more it has been fired and sized. The more it gets fired and sized the harder it gets. The harder it gets the more it wants to spring back opposite to sizing so it won’t get smaller and it will get larger while resisting the sizing die.
    So you need to find a die that sizes down more or you need to open the chamber a smidge to allow your current die to be enough.
    I have found ADG brass to do this more than others. But yeah I'm afraid so. The die might be harder I think a good polishing be easier cheaper and faster
     
    So the reamer specs should be .5510 at .200 line 30 nosler my brass fired is .548 to .549 sized I belive .548 .5475
     
    So yours does that all the time as well?
    Came across this late, but I had essentially the same issues and posted about it here: https://www.snipershide.com/shootin...-2-0-primary-extraction-difficulties.7112490/

    The universal answer I received was that it was caused high chamber pressures, despite the lack of high pressure signs. Since nobody wanted to think that there may be something else going on I pretty much dropped the issue. Now that other people have noticed the same primary extraction issues, while also lacking high pressure signs, makes me think there could be more to it.
     
    Came across this late, but I had essentially the same issues and posted about it here: https://www.snipershide.com/shootin...-2-0-primary-extraction-difficulties.7112490/

    The universal answer I received was that it was caused high chamber pressures, despite the lack of high pressure signs. Since nobody wanted to think that there may be something else going on I pretty much dropped the issue. Now that other people have noticed the same primary extraction issues, while also lacking high pressure signs, makes me think there could be more to it.
    There’s no way mine was high pressure. Mine was with a barrel I’d had on two other actions with a known safe load not even near the top end. Both savage actions and the Nuke I had set the headspace on so I know that wasn’t the issue. It didn’t do it every round fired and it also went away completely still shooting the same load. I have since added another barrel to the action and not had one problem.

    I just don’t buy it. After the initial break in it has completely disappeared.
     
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    I always seem to have this problem and don't get the speeds I think I should but maybe it's just pressure but had one barrel polished up and haven't put it back on yet to see.
     
    I always seem to have this problem and don't get the speeds I think I should but maybe it's just pressure but had one barrel polished up and haven't put it back on yet to see.
    Polishing a chamber can have negative affects as well. Most smith's with put a cross hatch with emery cloth on the chamber walls. This helps the case grip the chamber upon ignition reducing some the rearward thrust of the case head to the bolt. What is happening in thesr videos, the lower portion of case doesn't get sized enough for proper chamber fitment. It expands but doesn't spring back, and is causing sticky extraction. Over psi loads, too hot of a forming load, improper die to chamber fitment.
     
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    1671291872891.png

    id be curious to know what the fired brass measurement is on the head at the bolt face and then the same measurement on a piece of sized brass...id be willing to bet if it happens all the time its your die not sizing the the base enough.
     
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    I've had it happen in multiple calibers ect. The one barrel it honestly just stopped random one day. I just have 1 action and multiple barrels.
     
    View attachment 8023442
    id be curious to know what the fired brass measurement is on the head at the bolt face and then the same measurement on a piece of sized brass...id be willing to bet if it happens all the time its your die not sizing the the base enough.
    So I think from the top of my head the case at the .200 line was .548 - .5485 and resized was .5475 to .547
     
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    So I think from the top of my head the case at the .200 line was .548 - .5485 and resized was .5475 to .547
    With a 551 chamber diameter at 200 line, a fired case at 5485 should def NOT be sticking. Unless the smith used a heavily worn reamer.
     
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    So I think from the top of my head the case at the .200 line was .548 - .5485 and resized was .5475 to .547
    id still like to hear the measurement at the head not the 200 line....i still think this is a die issue not an action issue or a chamber issue unless like @406shootist said the reamer was worn or out of spec.
     
    I don't think I have any fired brass at the moment but I will check and let you know.
     
    Right now I'm using redding dies. This 30 nosler barrel berger says max for the 220 berger is 84 with n568 and I'm using 82 and get the clicker that's with adg brass
     
    Remove the barrel and measure how much protrusion a round or piece of brass has. If you do not have a depth micrometer use the shoulder measuring feature at the dial end of your calipers it will be more accurate and easier than using the depth feature.

    An ARC can have .150" protrusion on a case that big without issue. Likely it's binding in the case head where the die can't quite size it down enough.
    The problem may be solved by going to .150" protrusion if it doesn't have that much already.

    ...just an idea.
     
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    Some barrels are barrel nut style. So maybe that could be an issue. The cut isn't enough for the bolt?
     
    Some barrels are barrel nut style. So maybe that could be an issue. The cut isn't enough for the bolt?
    The case could simply be sitting too deep in the chamber and binding in the case head where the die can't size it down. Case heads grow over time and a die can't size them down enough. You need case head support to prevent separation but I have found they can be over supported especially with magnums which simply have more surface area to bind up the case. Almost every R700 clone and several others allow for up to .155" protrusion. Some Savage prefits can only have .125"-.130" of protrusion. That could be just enough extra surface area to give you that resistance at the top of the bolt lift.
     
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    Remove the barrel and measure how much protrusion a round or piece of brass has. If you do not have a depth micrometer use the shoulder measuring feature at the dial end of your calipers it will be more accurate and easier than using the depth feature.

    An ARC can have .150" protrusion on a case that big without issue. Likely it's binding in the case head where the die can't quite size it down enough.
    The problem may be solved by going to .150" protrusion if it doesn't have that much already.

    ...just an idea.
    Thank you for posting this.
     
    The case could simply be sitting too deep in the chamber and binding in the case head where the die can't size it down. Case heads grow over time and a die can't size them down enough. You need case head support to prevent separation but I have found they can be over supported especially with magnums which simply have more surface area to bind up the case. Almost every R700 clone and several others allow for up to .155" protrusion. Some Savage prefits can only have .125"-.130" of protrusion. That could be just enough extra surface area to give you that resistance at the top of the bolt lift.


    That makes since because it usually happens s after 3 to 5 firings
     
    I ran a 30Nos from sammi body spec chamber, used redding type S dies, adg brass. The problem with adg brass, the web area is thick and it is very resistant to sizing. Very tight dies are needed. I had no issues with die/chamber/sized/fired brass fitment. I had a spicey load of 3100 with 215 Bergers that would give me light clickers, it was warm. Ran it at 3010 without issue. Other thing, the first firing needs to be LOW psi. If you fireform at 65k psi, you blew out that web area as its softest first firing, ans now its larger than it should be and reducing sizing possibly. With a chamber at 551 and your sized brass at 5475, that should be plenty. Whats fired brass above the extractor cut?
     
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    No fired brass but I will. My loads are 82 n568 with 220 berger I think 3020 or 2980 off the top of my head in a 30 inch barrel
     
    The case could simply be sitting too deep in the chamber and binding in the case head where the die can't size it down. Case heads grow over time and a die can't size them down enough. You need case head support to prevent separation but I have found they can be over supported especially with magnums which simply have more surface area to bind up the case. Almost every R700 clone and several others allow for up to .155" protrusion. Some Savage prefits can only have .125"-.130" of protrusion. That could be just enough extra surface area to give you that resistance at the top of the bolt lift.
    ^^^^ THIS!! and thank you for putting numbers to this sir.

    @Schw15 as ive been saying your die is not sizing the base enough....i shot a BRX with the same exact issue...as a matter of fact it was 3 of us having this issue...i bought a small base die and that solved the issue and eventually i just ordered custom whidden full length sizers.
     
    ^^^^ THIS!! and thank you for putting numbers to this sir.



    @Schw15 as ive been saying your die is not sizing the base enough....i shot a BRX with the same exact issue...as a matter of fact it was 3 of us having this issue...i bought a small base die and that solved the issue and eventually i just ordered custom whidden full length sizers.



    I never doubted you I just need to go shoot and get some fired brass to measure more. Is whidden the best place for custom dies?
     
    i don't know about "BEST" i just know i did not like redding dies so i strated using forester which were great dies i really liked them. i started using whidden because they make custom dies(BRX issue)and the lead times were reasonable...i really liked the whidden dies as well.
    i can not comment on any other dies as these are the only 3 makers i ever used for rifle loading.
     
    We share same I do not like redding dies I'm a forester die guy myself but they don't make the 30 nosler or bushing dies. I need to talk to whidden I did awhile ago lead times were pretty backed up
     
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