Question on rifle cant

Discussion in 'Rifle Country' started by BWS, May 12, 2021.

  1. BWS

    BWS Member

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    Please correct,or shed light on this assumption;

    I ordered a,cheap enough,small anti cant bubble level for one of my rigs. In the meantime,have several of these little levels and am working on mounting solutions.

    Here's the question,or assertion;

    Is it safe to say,the more "rainbow" of a trajectory.... the more useful the level will be? I understand that if,you never changed range(say always shoot @100),and are sighted in for that,it sorta dosen't matter,as much.But this is about field shooting where range estimates have to be made,on the fly so to speak.
     
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  2. dave951

    dave951 Member

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    You are correct. Cant is a serious problem with rifles with a pronounced trajectory like a 45-70 etc, especially under field conditions.

    Here's the spirit level in the front globe sight of my 50-70 rolling block. IMG_20200920_083741.jpg

    And a shot of my rear sight
    IMG_20200920_083701.jpg
     
  3. edwardware

    edwardware Member

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    Formally, cant effects the Point of Impact as a function of the maximum offset between the Line of Flight, and Line of Sight. Range per se doesn't matter, but as range increases Offset increases unless you add velocity.
     
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  4. ApacheCoTodd

    ApacheCoTodd member

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    Yes.

    Note that the smaller a level is, the more important that its quality be. This is where I want etched glass of the highest quality or etched acrylic and I prefer a colored fluid that will not allow bubbles when vigorously shaken as a test.

    Todd.
     
    Last edited: May 12, 2021
  5. Varminterror

    Varminterror Member

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    I need to make a new one of these with a more relevant reticle and cartridge, and a longer range, but I’ve been too lazy since this does the job of showing the POI shift significance of canting a rifle or optic. I put this together for a hunting focused forum about 5 years ago to depict the influence of optic cant on point of impact. Shooting farther only creates even more offset influence.

    These 3 shots reflect a 30-06 fired at a measly 400 yards, holding over 4moa in a simple duplex. The orange dot on the reticle image is the target, held over 4MOA. The green line in the left reticle indicates the reticle is in line with the bore. The red lines in the other two show the reticle is not aligned with the bore. (Note: it may be counter intuitive, but for a canted rifle with a reticle aligned with the bore, the POI shift will be the same as the canted reticle case shown here, which is the larger influencer case. A canted rifle with an aligned reticle would also have a canted reticle, so it aligns with the canted reticle case, instead of the misaligned case of the canted rifle only).

    The bottom row of targets reflect the POI of each shot. The green dot with the X shows the respective POI for the shots, according to the cant of the optic or the rifle.

    Even at such a short range as 400yrds, the point of impact shifts notably. Missing by 2” at 400yrds might only be 1/2moa, but when you stretch that out to 600, and you’ve missed your target by over 4”, plus your raw group radius, stuff can become pretty critical.

    A981A5EA-9E0E-4428-B5D2-B401D6D012D7.jpeg
     
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  6. Walkalong

    Walkalong Moderator Staff Member

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    And one that reads the same either way you turn it, many do not. ;)
     

    Attached Files:

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  7. BWS

    BWS Member

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    Level came in. $8 to the door,which is what I wanted so wouldn't be the least bit afraid of modifications.

    The Redfield 4-12 is in low,Weaver rings on a 2 piece Weaver base. The rear's on these(have this same setup on 4 rigs) have a relocated slot. Which leaves enough room to mount this level. It clamps to the base in front of the rear ring.

    Because the scope is so low,there "ain't" much clearance between the bttm of scope,and the top of the base. Took a measurement,then mounted the aluminum level in a horizontally oriented V block on the Bridgeport. Had to mill a 1" radius cut in the top of the level housing to clear the bttm of scope.Easy peasy.

    Have chores tomorrow but will try it out off the bench and get some pics with a report.

    I don't like it mounted to the rear base... because it's too close to your eye. Needs to be on the front base but I'd have to re-slot it and just want to try it before having to completely disassemble,moving front ring.... which isn't that big of deal. I pop these Weaver setup rings/bases off right much. A cpl rigs have 2 sighted in scopes,they're almost always within 2 clicks @100 when changed.

    But am not 100% sold on it even being on the base. Partly again,why it's an $8 level. You gotta start somewhere though.
     
  8. BWS

    BWS Member

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    Pics,so far. Will say,that I was NOT holding level before the install. And I shoot,a LOT.

    Screenshot_20210513-085644_Gallery.jpg Screenshot_20210513-085631_Gallery.jpg
    Screenshot_20210513-085625_Gallery.jpg
     
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