POI Shift

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  • OLM-Medic

    Banned
    BANNED!!!
    May 5, 2010
    6,588
    I noticed some significant POI shift. The interesting part is that it does not involve the suppressor. It happened with mounting my muzzle device. Suppressed and unsuppressed POI is roughly the same. I've always heard a muzzle device may affect accuracy, but the group size is about the same. It's just POI shift. I'm guessing maybe it's overtorqued.

    My only concern is that I want to mount this on my long range rifle, and I don't want any issues there, especially accuracy issues. Should I just be more careful with how tight I torque the muzzle device?
     

    BradMacc82

    Ultimate Member
    Industry Partner
    Aug 17, 2011
    26,177
    Buy multiple mounts, 20ft/lbs and rocksett (chadwin beat me to the punch).

    If going on a precision rig, document your shift, so you have a rough idea of what to expect POI-wise with/without.
     

    OLM-Medic

    Banned
    BANNED!!!
    May 5, 2010
    6,588
    Stay at 20 FT# and use Rocksett. What you are describing is quite common.

    I think I way overtorqued this one. It didn't seem to affect grouping though. Just the POI shift. I'll probably be more careful with my bolt action though.

    I also used red locktite over rocksett, which Rugged claimed would be just fine. Kind of wish I used Rocksett now...but I'm not sure if it's a big deal.
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    I think I way overtorqued this one. It didn't seem to affect grouping though. Just the POI shift. I'll probably be more careful with my bolt action though.

    I also used red locktite over rocksett, which Rugged claimed would be just fine. Kind of wish I used Rocksett now...but I'm not sure if it's a big deal.

    If it's a bolt gun Loctite is fine, but I question any manufacturer that condones it use on muzzle devices and gas systems.

    Rockestt is for guns that get hot.

    I would remove the muzzle device and reinstall though.
     

    erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    I also had a 9mm rifle have some substantial PoI shift when I put a suppressor on it, and interestingly, retained the PoI shift even when I took it off. Still investigating the specifics of what's going on there - it has a pencil barrel and a not-real-firm trunion, so G-d only knows the real story. Last time I had it out was before a pistol class, so it wasn't a real focus at the time other than "huh, I wonder why that's going on".
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    I also had a 9mm rifle have some substantial PoI shift when I put a suppressor on it, and interestingly, retained the PoI shift even when I took it off. Still investigating the specifics of what's going on there - it has a pencil barrel and a not-real-firm trunion, so G-d only knows the real story. Last time I had it out was before a pistol class, so it wasn't a real focus at the time other than "huh, I wonder why that's going on".

    AR?
     

    OLM-Medic

    Banned
    BANNED!!!
    May 5, 2010
    6,588
    If it's a bolt gun Loctite is fine, but I question any manufacturer that condones it use on muzzle devices and gas systems.

    Rockestt is for guns that get hot.

    I would remove the muzzle device and reinstall though.

    Someone was telling me that YHM doesn't even recommend threadlock at all of their devices. Not sure if that's true but I was surprised.

    Ah, I guess I should change it out. Some people claim they use red with no issues in high volume shooting, but it clearly say it isn't rated for that.

    Is it hard to remove from the gunk from the threads after break the red threadlock?
     

    OLM-Medic

    Banned
    BANNED!!!
    May 5, 2010
    6,588
    Also, I was wondering if you could temporarily use a QD mount to "direct thread" a can for temporary measures.
     

    Hawkeye

    The Leatherstocking
    Jan 29, 2009
    3,971
    Chad, a question for you if you have time:

    I just brought this up in another thread, but Rugged's muzzle devices have wrench flats that are too short / thin to allow you to use most "normal" wrenches - when you get the device threaded on to the muzzle, there isn't enough of a gap between the washer / shim on the barrel shoulder and the back of the device for the wrench to get in there and grip the flats. I asked Rugged about it and they pointed me to a set of thin open end wrenches that they said is what they use. Thus, you can't use any of the "normal" wrenches that you could attach to a torque wrench. Now, I've torqued enough stuff over time to have a general feel, so I did it by hand with one of their thin wrenches. I'm fairly certain I didn't over-do it that much if any, but say someone did, and it over-torqued enough to affect POI.

    Would you typically expect to see things return to normal if the muzzle device is later unmounted and then mounted with proper torque, or would this somehow deform the end of the barrel enough to make a permanent change to POI?
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    Chad, a question for you if you have time:

    I just brought this up in another thread, but Rugged's muzzle devices have wrench flats that are too short / thin to allow you to use most "normal" wrenches - when you get the device threaded on to the muzzle, there isn't enough of a gap between the washer / shim on the barrel shoulder and the back of the device for the wrench to get in there and grip the flats. I asked Rugged about it and they pointed me to a set of thin open end wrenches that they said is what they use. Thus, you can't use any of the "normal" wrenches that you could attach to a torque wrench. Now, I've torqued enough stuff over time to have a general feel, so I did it by hand with one of their thin wrenches. I'm fairly certain I didn't over-do it that much if any, but say someone did, and it over-torqued enough to affect POI.

    Would you typically expect to see things return to normal if the muzzle device is later unmounted and then mounted with proper torque, or would this somehow deform the end of the barrel enough to make a permanent change to POI?

    Normally the consistency will return if you dismount the overtorqued device. The only instances where consistency failed to return were cases in which several thousand of rounds we're fired while the overtorqued device was installed.

    As far as thin muzzle device flats you can buy expensive tappet crows foot wrenches, or you can do like I did and buy cheap crows foot wrenches and grind them down so they fit.
     

    woodline

    Ultimate Member
    MDS Supporter
    Jan 8, 2017
    1,947
    Normally the consistency will return if you dismount the overtorqued device. The only instances where consistency failed to return were cases in which several thousand of rounds we're fired while the overtorqued device was installed.

    As far as thin muzzle device flats you can buy expensive tappet crows foot wrenches, or you can do like I did and buy cheap crows foot wrenches and grind them down so they fit.
    I don't suppose those are something you could offer for sale at a reasonable price? I'd love to support your business if you offered something that would work for sale on your site.
     

    OLM-Medic

    Banned
    BANNED!!!
    May 5, 2010
    6,588
    Normally the consistency will return if you dismount the overtorqued device. The only instances where consistency failed to return were cases in which several thousand of rounds we're fired while the overtorqued device was installed.

    As far as thin muzzle device flats you can buy expensive tappet crows foot wrenches, or you can do like I did and buy cheap crows foot wrenches and grind them down so they fit.

    Does it matter if it's overtorqued if the accuracy is still fine?

    i.e. group size is the same...just had a shift in POI and had to re-zero.
     
    Someone was telling me that YHM doesn't even recommend threadlock at all of their devices. Not sure if that's true but I was surprised.

    Ah, I guess I should change it out. Some people claim they use red with no issues in high volume shooting, but it clearly say it isn't rated for that.

    Is it hard to remove from the gunk from the threads after break the red threadlock?

    I did not see instructions to use any thread lock on my YHM devices. And I just looked to confirm on their site, and they don't. But I used Rocksett anyway, because Chad said so( SO he don't whoop my arse), and because I don't feel like having a bullet go through my can when it pops loose. I don't see how Rocksett could be of any harm.
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    I don't suppose those are something you could offer for sale at a reasonable price? I'd love to support your business if you offered something that would work for sale on your site.

    I'll be offering all of my customers tools and gauges once I get everything squared away.

    I just don't have a time table yet. Lots of iron in the fire now.

    Does it matter if it's overtorqued if the accuracy is still fine?

    i.e. group size is the same...just had a shift in POI and had to re-zero.

    If it were mine I would dismount and remount to be sure all is well, but that is my nature.

    It's your rifle my friend. I don't think anything catastrophic will happen if you leave it be.

    I did not see instructions to use any thread lock on my YHM devices. And I just looked to confirm on their site, and they don't. But I used Rocksett anyway, because Chad said so( SO he don't whoop my arse), and because I don't feel like having a bullet go through my can when it pops loose. I don't see how Rocksett could be of any harm.

    :)

    The Rocksett may not be needed by the manufacturer but if/when the can carbon locks to the mount you want the mount to stay on the rifle and not come off with the can.
     

    OLM-Medic

    Banned
    BANNED!!!
    May 5, 2010
    6,588
    I'll be offering all of my customers tools and gauges once I get everything squared away.

    I just don't have a time table yet. Lots of iron in the fire now.



    If it were mine I would dismount and remount to be sure all is well, but that is my nature.

    It's your rifle my friend. I don't think anything catastrophic will happen if you leave it be.



    :)

    The Rocksett may not be needed by the manufacturer but if/when the can carbon locks to the mount you want the mount to stay on the rifle and not come off with the can.

    I'm not as concerned about the torque as I am the darn red lock tite you have me worried about. I just don't want the thing coming off mid shoot and blowing my can apart.

    Unrelated note, is it okay to temporarily use a muzzle device as a direct thread, just to test it out in a bolt gun before mounting anything?
     

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