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LOS height above center of bore

Discussion in 'The Powder Keg' started by pappa, May 13, 2002.

  1. pappa

    pappa G&G Regular

    I may be all wrong..........but,
    I realize that all bullets start falling the instant they leave the muzzle. Hence, all scopes are actually mounted "lower" in front than at the rear, so that when you sight the scope on target, the muzzle is pointing to some degree "skyward".
    Let's assume a cartridge with a "flat trajectory" like a 7mm Magnum, not a "rainbow" one like the .38-55.
    I believe that the higher the scope is mounted, the greater will be the difference between POI and LOS, except for that one distance at which we have sighted in. If you've ever found it necessary (not by choice of course) to shoot something 25ft away with a scoped rifle, you will know where I am coming from.
    Anyone know of some good information, articles, etc on this?
    How much greater will be the effect with a 56mm objective, compared to a 50mm say, or a 40mm?


    :cheer: :full: :nod:
     
  2. Let's presume that all objective sizes are mounted at the same height above the barrel. The objective size effects the light gathering of the scope. It, in itself, does not change the LOS.
    The bullet starts from the bore below the LOS. At some point, it must "rise" through the LOS and later, "fall" through the LOS. Nominally these distances are 25 and 250 yards, or similar distances depending on ballistics.
     

  3. pappa

    pappa G&G Regular

    Hi Mike,
    Thanks for answering my post.
    However, I guess I should have mentioned what brought this up in the first place. For the application I am looking at, using an objective above 32mm will require increasingly higher scope mounts. Picture a .22RF or a CF rifle with a bull barrel contour. Standard mounts would set the 40mm hard against the barrel. And of course the 42, 44, 50, and 56mm will require higher than the 40 requires.
    Thus, in this case the LOS will be raised progressively higher and higher above the LOS. The largest objective scope I have personal experience using thus far is a 40mm.
    So, I am really looking for others experience with these larger objective scopes. (I see that some company even has 80mm objective scopes out now.)
    Obviously, the light gathering and/or field of view and maybe eye relief will benefit. Increased weight will probably be a negative.
    But there may be other negatives to these larger scopes that I am not aware of. In particular, where they do require higher mounting.
    :target:
     
  4. Hey papa,
    Don't know about you, but I am over 50 and the difference in light gathering of the larger objectives is beyond these old eyes. I think the biggest objective I have is about a 44 mm. Between the objective and the barrel contour, I had to use the high rings. As I haven't fired this rifle yet (busy weekends and poor weather), I am not sure what effect there may be. As the beastie is a 12 year old Ruger 77V, I have been chomping at the bit to try it. The trigger has been set by a 'smith and breaks at 2 pounds or so. Just like breaking glass.
    Wouldn't the higher rings just give a sharper angle to the LOS to offset the height difference??
     
  5. pappa

    pappa G&G Regular

    That Ruger sounds NICE!

    Hi Mike,
    Better make time to shoot that 77V; sounds like one sweet piece. A 2lb break glass trigger is gonna make you have to accept ALL the blame if you miss! Yes, my old eyes are tired too; I was live and kicking when the Japs hit Pearl. Are you guys having nasty weather in Texas, or is it just too darn hot there now? We have had "July' here for the past 5 or 6 weeks. Is your V a .223? Did you see the American Rifleman article last month on the Ruger 77 compact (I believe that's what they called it) and the Remington Seven? Take care, and good shooting!
    :gangster: :nod: :joker: :cheer:
     
  6. Pappa,
    She's a .243. Sits next to my 22 year old .280 Rem M77V. Gonna try to go out Tuesday (make the time to shoot!) Weather here in Iowa has been terrible. Up and down.
     
  7. Pappa,
    Fired the M77V in .243. Dern thing tried to put all the bullets in the same hole. Not sure what to do with it. Never had one that good.
     
  8. pappa

    pappa G&G Regular

    Don't EVER part with it!

    Great, Mike
    I am real pleased to hear that it shoots so well. Of course, you did your part, too. The Ruger 77 has a great reputation for quality and accuracy, not to mention that it is one of the more beautiful rifles there is. Were these handloads, or factory? I'll bet you shoot more often now.
    Have a good weekend,
    Pat
     
  9. Pappa,
    They were handloads. Now if I had written down how much of what, that would be nice.