• Getting Ready for PRS

      Some pointers for new shooters to PRS, so you can spend fewer PRS matches not performing so well due to a sub-optimal firing solution, and more time perfecting your shooting technique.

      Because there are multiple elements comprising the firing solution, each element will be covered individually. Problems encountered on the range relating to the firing solution can always be traced back to one of more of these individual elements.

      The first element of the firing solution is the rifle itself. The important parameters of this element are

      • bedding and pillars
      • scope rail
      • screw torque

      Specific off the shelf rifle solutions will have those three parameters pre-set, with no additional work required. When a general hunting rifle, or custom barrelled action is used as basis for PRS, these elements require careful attention.

      It is assumed that the rifle parts are assembled correctly, that the chamber is properly cut, and all the parts are free from defect.

      I mention this, because I have personally seen a high end, factory competition ready rifle with a chamber 20 thousands out of round. Don't assume your rifle is perfect because it's new, or because it was expensive. Check everything, or have it checked for you. It's a small price to pay for what could be months of shooting with a problem you can't identify.

  • Bedding

      Rifle bedding provides the action with a stable base. This means the action does not move in the stock either during use, or when experiencing a change in environment such as high or low humidity, wet weather, extreme cold or high heat.

      Integral to the bedding are the bedding pillars. These are usually of a harder material than the stock, and of course a fully metal stock does not have or need pillars. The purpose of the pillars is to prevent the action screw torque from deforming the stock where is contacts the action. This is why the action screws for a wooden stock are torqued differently to a synthetic stock, and in both cases differently when there are pillars.

      A barrel that is free-floated has an action that is bedded up to the chamber only, the rest of the barrel is not in contact with the stock, and this is preferred for PRS.

      Ensure your rifle is bedded properly, and the action screws are at the correct torque for your stock material with or without pillars.

  • Scope Rail

      Off the shelf rifle solutions usually come with the scope rail, and the better ones have the rail integral to the action.

      Actions that are drilled from the factory almost always have third-party rails that are made specifically for. An action with no holes for either a rail or scope mounts has to be drilled and tapped, and because the final solution accuracy hinges on this being done well, don't try get it done as cheaply as possible. Pay a reputable gunsmith to do a proper job.

      Rails are available with pre-set elevations, the most common being 0 MOA, 10 MOA and 20 MOA.

      In PRS, rails are the norm, scope mounts directly to the action are like unicorn sightings.

        The choice of rail is accompanied by the choice of scope, or the elevation adjustment available to the scope, and will be either 10 MOA or 20 MOA . For PRS, you want a scope with at least 60 MOA total elevation adjustment, and with a 60 MOA scope you can fit a 10 MOA rail. Scopes with over 80 MOA total elevation adjustment can be mounted to a 20 MOA rail.

        Pick a rail from a reliable manufacturer, don't try save money buying cheap. I once bought a rail at what seemed to be a good price, and the holes for the receiver screws had to be milled out to the correct size.

  • Screw Torque

      All screws must be torqued to their respective specification :

      • action screws
      • receiver screws for the rail
      • scope body screws
      • scope ring screws to rail

      Screws that are loosely torqued can cause accuracy to be unpredictable.

      Screws that are over torqued can

      • have their threads completely or partially stripped, and must be replaced
      • damage the stock if they are action screws
      • damage the scope body if they are scope ring screws

      At this point, you have the basis of your firing solution. The next step is mounting the scope to the rail.

  • Scope Mounting

      When a scope is fitted to a rifle, the scope must be levelled. A level scope will not induce any windage error on elevation adjustment. There is a very simple way to level a scope, which is described here

      Using this method, you can be sure that your vertical reticle line bisects the center of the rifle bore, which is the perfect condition to not induce windage error on elevation change.

      If you try this method, and your scope or your reticle appears canted when you shoulder the rifle, you have a reticle that is rotated inside your scope body. You can prove this condition by a tracking test, which will show that elevation change produces a windage shift.

      There are other scope levelling methods available, an online search will return many results, and you can always use the above method as a second validation of the one you choose.

      This rotated reticle condition can affect all scopes, irrespective of who made them or how much you paid for it, so the future tracking test is an important part of validating the firing solution.

  • The Load

      For accuracy, it is necessary to have a consistent load. This can be either factory ammo or reloads.

      A consistent load is one that

      • produces the smallest group size, consistently - and
      • has the lowest shot-to-shot velocity variation, consistently

      Do your best to get the most consistent load possible, it will give your firing solution the greatest accuracy potential.

      With the platform complete, and a load selected, it is necessary to test the scope.

  • Scope Testing

      The best backing to use for these tests is the packaging from large appliances - refrigerator, washing machine or dishwasher. Tall refrigerator packaging is the best.

        Make sure your scope tracks properly. Do this even if you have the most expensive scope, do not assume the scope is perfect. Test it.

        There is a lot of information online on how to perform a tracking test. A test outcome for a scope with a reticle rotated in the scope body is shown below.

        Adjusting elevation with no windage adjustment produced a windage shift to the left. This scope was sent back to the supplier, and replaced under guarantee as it could not be repaired.

        A box test with this scope yielded a slight parallelogram instead of square, but it was it was not immediately clear from that box test alone that there was a problem with the reticle. A tall target test can prove that.

        The ratio of expected windage adjustment to actual windage adjustment can then be included as a column on the drop chart, to calculate actual windage values.

        There are detailed instructions online to perform a tall target test.

        Follow the instructions from Bryan Litz on how to perform a tall target test, and derive the correction factor for your scope to use on the drop chart.

        The tall target test is the most important scope test for a PRS shooter to perform. The importance of the result, and applying the result to the drop chart, cannot be over-stated.

        The result of the tall target test is two-fold :

        • verify the scope is level, ie : the vertical reticle line bisects the bore axis
        • show the actual elevation adjustment

        The elevation adjustment factor can then be added as a column to the drop-chart, to show actual elevation adjustment next to the calculated value.

  • The Drop Chart

      To produce a drop chart, you will have already settled on a load. Any change to the load requires a repeat of this and the following steps.

      Use that, or your preferred similar software to produce a chart of bullet drop to the maximum distance that PRS shoots are held.

      Make sure to use the correct altitude and air pressure for your shooting location, as this greatly affects trajectory.

      REPEAT - Make sure to use the correct altitude and air pressure for your shooting location, as this greatly affects trajectory.

      If you do not adjust the drop chart to factor in altitude induced air pressure change, you will be missing a lot of shots.

      Copy / paste the chart output into a spreadsheet, and add blank columns - one for the correction factor and one for the corrected elevation adjustment.

        Verify the drop chart.

        To properly verify the bullet drop calculations, you should shoot to the maximum range on the drop-chart.

        It is important to actually go and shoot at that range, and not to first rely on any calculator, even if all the pros use it. You will save many weeks or months [ and a lot of ammo ] of trial and error by taking one day of your time to get to a suitable range and perform this test.

        Compare your actual elevation to what the drop chart says.

        If the elevation you have to dial differs from the chart, make a note of the actual, and re-visit all the input parameters for the calculation.

        Pay particular attention to use actual input data for

        • air pressure at shooting altitude [ critical input parameter ]
        • correct bullet BC, there should be no practical difference in result between a G1 or G7 number

        Tweak the numbers till the drop chart matches your actual.

        Physically verifying the drop chart cannot be done using ballistic software. Software works on the principle of rubbish in, rubbish out. Having an accurate, verified drop chart is the basis for moving on to field ballistic calculators.

  • Next Steps

      With a drop chart that corresponds to actual drop at maximum range, you have completed the fundamentals to setting up your firing solution for PRS.

      Now you are ready to move off the drop-chart, and on to using a ballistic calculator like Strelok, as you have all the correct, verified input parameters.

      When the bullet trajectory can be reliably predicted, you can focus your time and effort on practicing shooting technique.

      Having a reliable firing solution will make your practice sessions more enjoyable, and help build your confidence and shooting skills more rapidly, as the only variable that remains to be improved upon in the shooting equation is yourself, the shooter.