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Why are 16X groups tighter than 32X ?

jking

Member
May 12, 2015
2,531
71
62
Hobbs NM, United States
    I thought I had issues with my FX500 after I bored out the end cone and the air stripper to .330" a while back. One of our fellow members had done this to his and had positive results. I shot the other morning with basically zero wind, 80yds, JSB MKI's weight sorted and sized. I was shooting at 32X through my Sightron SIII 8-32X56 and wasn't happy at all with the results. I think all five, five shot groups were over I". I had seen this before when I had the power cranked up. I was to point of getting ready to plug them both and then re-drill them to factory specs. I decided to dial the power back down to 16X a couple of evenings ago and shoot 80yds and it was shooting great again. This morning while it was calm I shot these 5 shot groups and was really pleased. I just don't understand what the difference is. My bench is rock solid and I feel good about all the shots, don't remember pulling any anyway. Anyway here are those groups from this morning.
    Jimmy
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    weatherby

    Member
    Jun 5, 2015
    582
    38
    --, Belgium
      Jim my friend, I think Tom is spot on. :)
      S3's are quite sensitive to parallax adjustment, fat chance that it is a parallax error.
      Make sure your gun is steady, and adjust your parallax wheel until your reticle is not moving anymore when moving your head.
      When not adjusted properly, it is no exeption that this can cause a big poi change.

      cheers,

      Gijs
       
      I have the exact same problem. A few years ago I figured more power would improve groups. Went from 24X to 32 and 34X. No such luck. Groups got worse. Dialed back to 24X and everything came together. Dialed the 24X back to 16X and things improved with that scope. Personally I believe that the higher powers show my hart beat and breathing and so I fight it. But that doesn't explain why a maxed 24X was bad and a 34X set to 24X improved. Hell, it's a damned mystery! I've tried everything short of sacrificing a chicken. 
       

      jking

      Member
      May 12, 2015
      2,531
      71
      62
      Hobbs NM, United States
        Thanks guys, I normally check my parallax with the head bob and weave. Everything seems to feel good at the shot but apparently there's something to what ya'll are saying. I'll keep all this in mind on my next session and see what happens. 16X is what I'm set to for all my sight in and dope cheat card anyway.
        Jimmy
         
        "chasdicapua"Lots of sub MOA there Jimmy, and damn, that .287 is s w e e t. The Royale 500 is a shooter for sure. 

        Komment:
        o.250 actually. And we are talking 5 shots 80 yds here! If I hadn`t seen the other groups, I wold not believe 5 pellets passed through.
        GREAT shooting!!

         
        99% chance that this is a parallax issue. Best way to determine if parallax is the problem, is to fixate your scope, set it to a target at 50 yards or so and move your head behind the ocular lens in all wind directions. If you see the crosshair move in relation to your target, than parallax is the problem. You can compensate for that (if your scope is of decent quality) by adjusting the ocular lens ring. Try to turn it all the way in, and then in 45 degree increments - do the moving around - turn it out all the way up to the point the reticle becomes blurry. Somewhere down the line the parallax should be solved. If not, your scope is probably defective. Prior to all this, make absolutely sure your scope is in focus!
         
        Hi guys:

        It is my understanding that at higher magnifications any scope becomes more sensitive to each and every external factor like your heartbeat, your breathing, your hand grip, so the minimum lack of control on any of these factors will affect your accuracy, especially at long distances. My two cents.

        Regards from Mexico

        José Palma
         
        That's why you should test the scope by fixating it and moving your head to see if the reticle and target don't move in relation to each other. If that test passes, you know it's the shooter. But since he shoots great groups at 16x, my guess it's a parallax issue. That is more noticeable and has greater effect at higher magnifications. ;) 
         

        jking

        Member
        May 12, 2015
        2,531
        71
        62
        Hobbs NM, United States
          Thanks for the comments guys,
          Jonnes, one thing I have noticed is that when the scope is focused on the target at it's maximum, that at longer distances there is parallax issue. To get the cross hair or dot in my instance to be at it's best as far as doing the head bob. I have to re-focus just slightly to correct the parallax. The target is then not at it's best focus, close but there is a slight difference. Jonnes are you saying that by adjusting the ocular lens these two conditions can be corrected?

          Gunner,thanks, I guess the stars aligned on that best group. That's the best group I've ever shot...Period!!
          Jimmy
           
          Correct Jimmy, that is if you have a scope that's of decent quality. If it's slightly out of focus when the parallax is corrected with the parallax adjustment/focus wheel, you can try and correct the focus by using the ocular lens ring. Almost nobody uses this, but it's one of the most essential parts of scope adjustment. In Special Weapons Training there's a whole chapter on rifle scopes with just the technical aspect of scopes, that wil keep you busy for at least a week.

          Parallax is an issue with almost all budget (sub $500) scopes. Getting completely rid of issues like these is one of the things that makes good quality scopes so damned expensive. It all has to do with perfect (cut, coated, and fitted) lenses and even more perfect alignment of all those pieces of glass, even after being moved internally from because you adjusted them the focus or zoom knob. One thousands of an inch off, and you have a scope that's basically useless for precision shooting. If you step down and really think of this from an engineering point of view, it's actually pretty amazing stuff that we all take for granted when we shoot.

          But anyways, now we've determined that parallax is the issue, a few other things come in play. Either you corrected the focal issue with the ocular lens adjustment and Bob's your uncle, or it's a poor quality scope, it's damaged somehow (tightened the scope rings to hard once or twice) or you have poor eye sight. Don't underestimate eye sight, because I've trained a LOT of shooters that where having problems getting perfect shot alignment each time because they wore cylindrical prescription glasses. With those, you have to align your head and glasses in front of the eye piece exactly the same, each time, and that's something that's damned near impossible. Ever wondered why you don't see snipers wearing glasses? Because 20/20 vision in that line of work is essential. ;)

          Just a small other tip that's directly related to this whole discussion, never EVER over tighten your scope rings. They need to be fixed at a maximum torque of 2 Nm or 18 in/lbf, and no more! I've seen scopes that had dents that were caused by over tightening the rings, resulting in the lenses getting out of alignment rendering the scope useless. Or over-shimming scope rings that ever so slightly bend the scope tube, ending up with the same alignment issues.
           
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          Oh, and bear in mind that parallax is set for the range your parallax/focus ring is set at. If that's 50 yards, you'll start noticing parallax issues beyond that. This makes sense, because the parallax is set to 50 yards, not 55. From a focus standpoint, there's no real noticeable difference between the two, but with regard to parallax it is. So always check the range on your parallax adjustment wheel with the range of your target, preferably with a range finder.
           
          Glad to be of service Jimmy. Hope you'll solve the issue, if not I suggest shooting at lower magnifications and save up for another scope. I recently bought an Athlon scope myself for one of my rimfire's, an Argos 8*32/56 with BTR reticle. You honestly can't get anything better for that amount of money, and they have a life time warranty (no questions asked policy). One of those $500,- Athlon's can be compared to other major brands at twice the price.

          Let me know what your conclusion is, okay?
           

          jking

          Member
          May 12, 2015
          2,531
          71
          62
          Hobbs NM, United States
            Well, I shot again this morning while there wasn't any wind to speak of and the coolest part of the day. Set the scope to 32X and checked the parallax for focus first and then alignment doing my best Owl imitation. Really couldn't detect and noticeable misadjustment so I shot three warm up shots to make sure the velocity and regulator was all good. One of the things I like about my 500 is that it's spot on from shot one. My other two PCP's need a few shots to get to cruising speed. Anyway my groups averaged right with the groups from earlier that I shot at 16X. The 16X slightly better due to the .287 group. I used a target aim point of circle that was .250-.270" and kept the reticle dot within the circle for the shot cycle. Could of used a smaller circle with the fine dot of the Sightron scope even at 80yds (I love that small dot). I could definitely see my movements while trying to stay on/in the center. Might try 24X for a happy medium next time..
            Jimmy
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