Gun won't shoot with a can!

Nostradumbass

Nostradumbass

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Minuteman
    • Sep 7, 2009
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    NE Texas
    #1
    I've tried a lot of different loads before I've came to this conclusion..... I've got a 6.5X47 Lapua that shoots <1/4moa consistently, but when I screw my can on it the groups open up to about an inch. I've shot some 1/2moa groups, but I can't do it every time like I can without the suppressor. This is at 100 yards, I haven't shot paper any further yet, but have shot steel at 500 yards with good results.....if there's anybody whose had this issue, please share it with me.......and also it might just be me! I've been told that already.
    Thanks,
    Phillip
     
    #4
    Re: Gun won't shoot with a can!

    Nostra, a supressor can (and often does) change barrel harmonics significantly. I have a good friend who has two, one a 308 and one on a 260. I don't own one, but can tell you that he had to do new load development in both cases when he went from bare bones to using his supressor. I have another buddy who has one on his 260, and I don't know what his experience has been, damn rifle shoots AWESOME with it on there, but I can check and see if he had to re-do load development when he put the can on his rig.

    I will be interested to see what more experienced members here advise, but I know based on my one friends experience, it can be as simple as needing to rework through load development.

    Good luck.
     
    #5
    Re: Gun won't shoot with a can!

    Okay...it's a Shark 30cal suppressor, and the gun was built by Ben Grigry...I believe he's here on the hide......he cut the threads concentric with the bore, not the barrel OD......his work looks good IMHO
    The suppressor is a single point attachment design.
     
    #6
    Re: Gun won't shoot with a can!

    boltripper thinks there is a bit of voodoo that has to be employed here.....for example, savvy the distance from the crown to the first blast baffle......sometimes a combination of the weight of the can on the barrel and thread length will goof on the groups.

    i see this effect me on several rifles using two different cans....and thus i prefer using one can over the other in certain times to effect maximum accuracy.

    also....some barrels worn that need to be fouled a lot....snap to it rather quickly by just screwing on a can...


    ymmv
     
    #7
    Re: Gun won't shoot with a can!

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fish301</div><div class="ubbcode-body">Nostra, a supressor can (and often does) change barrel harmonics significantly. he had to do new load development in both cases when he went from bare bones to using his supressor. </div></div>

    This.
     
    #8
    Re: Gun won't shoot with a can!

    I have seen it is sometimes a velocity issue, where the increased velocity with the design of the can creates turbulence in the wrong places...

    An example of this, with my Shark is using 170gr HPS rounds from Lapua... about 200fps faster than your typical load, like any 175gr match load. Well with my Shark the 170gr stuff is all over the place... it works great with loads around 2600 - 2650fps, but when you start approaching 2800fps, it throws them all over. Take the can off, no problem they are accurate again.

    Cans produce a certain turbulence to be quiet, I think managing that turbulence gets out of hand when they rise above a certain level.

    Also it maybe in the design of the can's crown. I know some are better than others, and the crown on the can, I have seen effects the overall accuracy. That includes having a suppressor cover that hangs over the edge. If you have a can with a good recessed or relived crown, no problem, have a flatter nose on your can and hang a cover over it, you have disruption that causes accuracy issues.

    Lots of speculation on my part, but i have seen it too, isolated incidents but worth noting.
     
    #9
    Re: Gun won't shoot with a can!

    Frank, are you saying you see a 200fps increase in velocity with that ammo when you attach the can, or just that you're chrono'd numbers with that rifle + can get you about 200fps beyond the average loading found in the world?

    Everything you listed is the reason that load development must be done with suppressor attached, so long as you are certain the bullet is coming out stable and won't strike a baffle. Usually not a problem in full speed loads, but subs should be worked with the can off first, then redone with the can on after stability is checked.

    In the case of a shooter who doesn't reload, you can try to time the suppressor differently to adjust for POI shift... but it likely will not affect group size much, if at all. In this situation you'd have to just test different ammo until you found one that offered the best accuracy.
     
    #10
    Re: Gun won't shoot with a can!

    Know nothing about your stick/can combo.

    With mine because I'm just under pressure with my std load of 45.2 grs of Varget, 175smk BR-2, Win case, everything is fine can on or off. Change load to 45.2 Varget 175smk, RP case, 210M, fine w/o can, but with the can on it opens up to well over an 1".
    Remember, cans add pressure, small as it is, if your at the ragged edge of it w/o the can, adding a can, may put you over the edge and groups will open up.
     
    #11
    Re: Gun won't shoot with a can!

    The HPS load is a factory load and has increased velocity by design. In fact the primers are staked from Lapua to prevent it from blowing them out.

    As been written above me, velocity matters, and cans are sensitive to that, depending on the design of the can itself.
     
    #12
    Re: Gun won't shoot with a can!

    Remember the old Browning BOSS systems (Winchester used them also) and how just a small change (in or out) would affect barrel harmonics, and groups?

    You may need to build a load that works with the harmonics generated when the can is installed, and use that load to shoot supressed. I know of other guys with the same issue.
     
    #13
    Re: Gun won't shoot with a can!

    Is it possible that when attaching the can to the end of the barrel that the added weight is now causing the barrel to touch the stock during its whip and causing the harmonics not to be the same ?
     
    #16
    Re: Gun won't shoot with a can!

    Perhaps just my weird of doing things
    If to be shot primarily suppressed then it would only make sense to develop load with can in place.
    Yes hanging a weight on end of barrel will affect harmonics, maybe just dumb luck on my part but loads developed this way shoot as good with can removed.
     
    #18
    Re: Gun won't shoot with a can!

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ptd</div><div class="ubbcode-body">Did you work up your loads with the can? May want to give it a try if not to see if it makes any diff.

    -pd </div></div>

    Did you happen to read the thread and see just how many times that has been mentioned already?
     
    #19
    Re: Gun won't shoot with a can!

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Killer Penguin</div><div class="ubbcode-body">
    Did you happen to read the thread and see just how many times that has been mentioned already? </div></div>

    I see lots of mention and speculation but I do not recall anyone asking the original poster for confirmation on his load development and if it included the can or not.

    -pd
     
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