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Questions about the USO Elevation Mod on Unertl

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  • Questions about the USO Elevation Mod on Unertl

    I might end up buying one some day after I save my lunch money and was wondering what exactly is the Elevation mod and did they replace the internals of the turrets to make it work?



  • #2
    They replaced the original leaf spring with a coil springs. Once the modification is done to an original Unertl, I can be rebuilt like it was originally made but it'll still have that big manhole cover size plug.
    Last edited by Game Warden; 05-03-2016, 03:34 PM.

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    • #3
      Possible ignorance to follow.........

      Im surprised Unertl didn't use the elevation mod in the first place.

      Im assuming the manhole is a seat for a coil spring that keeps the crosshair cell pressed against the elevation and windage adjusters.

      Same idea as Unertl external mounts.

      I think the original scope used leaf springs, bottom/side of scope to maintain the cell against the adjuster.

      The mod added elevation/restored elevation on the A3

      So yes the internals were replaced as far as the crosshair cell goes but I think the adjuster rods stayed the same.
      Last edited by pmclaine; 05-03-2016, 02:49 PM.
      "...But they would never find anything to beat the old Springfield ...the long sleek streamline, very slim but with potent bulges, all in the just exactly right places to give it that pugnaciously forward-leaning, eager look that marked the Springfield. Beside it, the M1 looked like a fat old man puffing with a lack of training...the two most beautiful things made in America were the ax-handle and the clipper ship? ...they should have added one more thing: The Springfield '03 rifle..."

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      • Game Warden
        Game Warden commented
        Editing a comment
        You are right. It did originally have leaf springs, not a coil. I fixed my post above. That's what happens when I try to think with kids using me as a jungle gym.

        The original M40A1 base is a 0 MOA base. In order for the scope to line up in trajectory in the M40A3 30 MOA base, the spring modification had to be made.

    • #4
      I know that myth, wives tale, common knowledge dictates the spring mod/change to be an improvement, or a correction of a problem associated with canted bases, but the simple and true answer is good old economics. Using the coil spring accomplished several things for USO. First, the coil springs were already on-hand, by the thousands. They're the same as the spring used in all the other scopes USO builds. Second, using the coil spring eliminated the need to have a spring maker make the proper leaf springs. Third, and most importantly, it allowed USO to delete one of the machining processes to the reticle housing (I don't remember the actual name of this piece) that is located within the rear tube portion. Simply stated, it was easier and cheaper to go this route.

      And, we've all seen original Unertls in their uncut form on M40A3's with no problems achieving zero. Look on the CMP forum...

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      • #5
        I would beg to differ about the mods. Achieving a zero and maxing out your elevation is drastically different. The modifications did help. Trajectories do not always line up with the unmodified scopes. If you run an original Vs. an A3 mod scope side by side with equally able shooters, it will vary. I'm not the only one to say this either.

        I do believe that the mods were cost efficient and increased production time. I do however know that ammo varies from lot to lot. I do know that no two shooter are the same but I have seen two instructors run this test and seen the results. Can the unmodified scope work on the A3...yes. Do you have to max out course and fine tune elevation...yes. Even then, you may have to conduct a hold. This is only from my personal experience and watching two 8541 surgeons operate with new M40A3s when they first came out.

        And with that...I'm done.
        Last edited by Game Warden; 05-03-2016, 05:37 PM.

        Comment


        • Skunk
          Skunk commented
          Editing a comment
          GW,

          The springs would only effect the scope's ability to achieve zero (bottom end travel) and would not have any effect on being able to get POA/POI at extended distance (the other end of the erector's travel). The springs have nothing to do with the erector tube interfacing the knob feet.

          I agree with everything you say above but wanted to clarify what I was saying.

      • #6
        I am not a subject matter expert. We all also know that I'm not smart enough to be an engineer in any manner or kind. We were told that the because of the way the coil spring pushed at an angle that you didn't get the same exact come ups on the scope. The original design allowed for the scope to be adjusted up and down, where as the modification makes it move at a oblique fashion.

        I can easily be wrong. I do believe in the seeing is believing but doing and collecting the results for yourself...that's the ticket.

        If you are ever at Camp Lejeune, I'd like to talk guns sometime. Hell, even go shooting. Many of men here are more wise than I. 😉
        Last edited by Game Warden; 05-03-2016, 08:51 PM.

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        • #7
          Ive wondered about whether the cell moves at an oblique after looking at my external Unertl, with the 1930 hr position coil spring, and wondering how do you avoid getting windage when you adjust elevation when the adjuster foot is riding a round tube.

          The only way I can see avoiding it is a square cell where the adjuster rides a flat surface. Than the cell will only track Up/Down or Side to Side.

          But scope tubes are not square and a square cell would limit either your elevation or windage.

          Somehow the geometry works otherwise my external Unertls wouldn't hold 0 wind when I go from 100 to 300 or even out to 600.
          "...But they would never find anything to beat the old Springfield ...the long sleek streamline, very slim but with potent bulges, all in the just exactly right places to give it that pugnaciously forward-leaning, eager look that marked the Springfield. Beside it, the M1 looked like a fat old man puffing with a lack of training...the two most beautiful things made in America were the ax-handle and the clipper ship? ...they should have added one more thing: The Springfield '03 rifle..."

          Comment


          • #8
            When they switched to the M40A3, I wonder why they went with the deep MOA base? It wasn't really necessary since they were still using the same scope. I don't see the benefit?

            The rifle below, I was able to zero it no problem. Didn't test the come ups though. I have another one on the way. I'll mess with it and see what the results are.

            Comment


            • #9
              Originally posted by pmclaine View Post

              The only way I can see avoiding it is a square cell where the adjuster rides a flat surface. Than the cell will only track Up/Down or Side to Side.

              But scope tubes are not square and a square cell would limit either your elevation or windage.
              Ah! But there IS another way! The erector tube is round, but the adjusting rods are flat and perpendicular. As long as the tube stays on the flat surfaces of the rods, the tube will track straight across them

              And this brings me to the disappointing surface I've seen on USO adjusting rods.............

              Anyway, regardless of which spring configuration is used, they are just biasing springs. In other words, they are simply there to keep the erector tube pushed against the elevation and windage adjusting rods for positive positioning. Elevation and windage movement is mechanical, and it doesn't make any difference which bias spring method is utilized, IF IT IS WORKING PROPERLY.

              The problem with the leaf springs is that one spring can pinch and hold the erector tube off of the adjacent adjusting rod upon recoil if the adjacent spring is weak, leading to a faulty POI for the next shot. And weakened leaf springs were reported to be a problem. With a single, diagonal bias, there can be no such issue. Being a purist, though, I prefer Unertl's design, original leaf springs and all.

              Old, dried or insufficient lube at the contact points can also cause or exacerbate this problem.

              Last edited by SemperFi; 05-04-2016, 12:53 PM.
              You can take a Marine out of the Corps, but you can't take the Corps out of a Marine.

              Comment


              • pmclaine
                pmclaine commented
                Editing a comment
                The key than is.......As long as the foot of the adjusting rod is wide enough so that some portion is always in contact with the widest diameter of the erector tube than yes you keep everything adjusted.

                I'll have to pay more attention to my external Unertl next time I have one out. If I remember right the foot on those is kind of rounded.

              • SemperFi
                SemperFi commented
                Editing a comment
                Maybe you're thinking of the rounded bias spring plunger?

                I can't speak for every externally adjustable scope out there, but mine has a flat bar between the adjusting screw rod and the scope tube, so that the adjusting screw isn't rotating directly on the scope tube.

                By the way, the erector tube in a USO/Unertl MST100 moves a LOT less than you seem to think. It only moves about .045'' at the adjusting rod contact point for the full 37.5 MOA elevation you need to get to 1000 yards. And, the diameter of the tip of the adjusting rod is .219'', way more than enough surface for the tube to stay in contact for the amount of travel needed.

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