Gun-ology – Working up a new rifle/scope, 3 options   Recently updated !


If you are like me, in that you have a lot of rifles and you shoot many different configurations, then you probably spend a lot of time getting guns sighted-in. When I first started sighting-in rifles, I had only 1 way, and it was like taking a rifle on a date – it ate up a chunk of my day.  Whether being quickly forced to sight-in 5 or 6 guns at a time, completing gun builds, working out configuration issues, or preparing for some of my adventures, I was forced to become more efficient and proficient with my range time.  Here, I present the 3 basic programs I use to sight-in rifles.

Just Sight-In Quickly

If you just need to get a rifle “shooting” on paper with precision  and with the least amount of range time, then the “One Shot System” and/or “Short Distance Zero” methods can’t be beat.

One Shot System

The “One Shot System” method consists of the following steps:  making a shot on a target, centering your gun on the bullseye and using the turrets to adjust the reticle back to where your shot landed. Once you have moved your reticle back to where your shot hit, you are, theoretically, sighted-in. Many advocates of this system recommend a 2 shot variation where you take a second shot and verify. There are tons of online videos explaining this technique – here is the simplest video I have found.

Short Distance Zero

The one issue with the “One Shot System” method is that not every scope has easy to turn turrets on the scope which allow you to hold your weapon on target and adjust the turrets.  Though more scope manufacturers are adding them, the bulk of scopes sold are low-to-mid range sporting scopes which won’t have quick-turn turrets. Therefore, we offer an alternative to the “One Shot System” method – the “Short Distance Zero” method. We suggest 10 yards because we have had scopes so far off mid settings that we could not get them on paper out of the box at 25 or 50 yards (I do not always bore sight my scopes). If you bore sight, or are pretty sure yours is not too far off, you can pick 25 or 50 yards.

Steps to follow in calculating “Short Distance Zero”:

  1. Take a shot while aiming at the center of the target.
  2. Measure the distance (in inches) up/down, right/left from center (Note good targets have a 1″ or .5″ grid).
  3. Determine the number of clicks your scope requires to move 1 inch at 100 yards:  1 MOA (Minute of Angle) = 1 inch at 100 yards (suggestion, read your scope instructions before hitting the range!). Calculate the number of clicks (both up/down, and left and right). The formula is: <number of clicks to move an 1″> X <number of inches off> X <10 if a 10 Yard or 4 if a 25 Yard or 2 if a 50 Yard sight-in>.
  4. Correct the scope setting by the calculated number of clicks in the necessary direction (read the dial to determine the right direction to turn).
  5. Take a second shot:  if not in the bullseye, then repeat steps 2 – 4.
  6. Once you hit the bullseye, mark your existing shots and then take a 3 shot group. The shots should center around the bullseye.

If you are repeating steps 2-4 more than 3 times, go back and check your math. Also, note that 1 MOA is not actually 1″, especially at shorter distances. For Example, 1 MOA at 100 yards is actually 1.04 inches, at 50 yards is .52 inches, and at 25 yards is .26 inches. Therefore, if you are sighting-in at 10 yards, you may actually want to use 8 or 9 versus 10 as a multiplier. Pragmatically speaking, you will overshoot if you use 10 as a multiplier.

When using either the “One Shot System” or the “Short Distance Zero” method, your rifle should be sighted-in. However, if you depend on your rifle for this accuracy (survival, tactical, hunting…) you should follow one of the next methods – realistically you have not ensured both precision and accuracy.

Point Blank Zero

A point blank zero (PBZ) entails sighting-in a rifle/scope/load for a specific working profile. The goal is to be able to hold center on a target over a given range, and to place a round inside a fixed size – say 4″, 6″ or 9″. Hunters often use PBZ when sighting-in a rifle/scope to know they can hit an animal kill zone (say 6″) over a range (say 0-250 yards) and not have to change any further settings on the scope.

Unless you want to manually do the math using the ballistic data from a load, the best course of action is to enter the load data and PBZ parameters into a PBZ calculator (like the one over at ShootersCalculator.com). The process is straight forward. The output is a range you “zero” in the scope, and the point blank zero range over which your PBZ will hold (minimal and maximal).

Once you have the PBZ calculated, you may choose to use one of the quick sight-in methods as listed above to get on target at the point blank zero range (often under 100 yards). When this is accomplished, you want to make sure you shoot 2-3 groups of 3 rounds to ensure you are holding and grouping on this zero range.

Full Workup

If you shoot at a lot of ranges, or you want a rifle sighted-in for a specific load to be pinpoint accurate over its ballistic range, then a “Full Workup” is required. Once a rifle has been “fully worked up”, then a “dope card” can be developed for the rifle/scope/load. A “dope card” allows a shooter to quickly adjust scope settings for various range/environment conditions and achieve the optimal accuracy possible under field conditions.

A full workup consists of the following steps:

  1. Calculate the ballistics for the load data you intend to shoot. This will be critical to have throughout the rest of this process.
  2. Identify your zero distance. This can be:  more frequent shooting distance (100 yards), a PBZ distance, or some longer range based on your load data ballistics and needs.
  3. Use one of the quick methods to get a gun/rifle on target – preferably, this is done at your zero distance if it is at or under 100 yards. If your zero distance is beyond 100 yards, pick a distance under 100 yards in order to get the rifle/scope hitting at center.
  4. If step (3) was not performed at your zero distance, calibrate your rifle/scope at your zero distance. Again, once completed, shoot 2-3 groups of 3 rounds to verify the integrity of your zero.
  5. Once zeroed, it is important to:
    • Verify scope turret changes by “boxing” your scope. This is where you:
      • shoot a group at the center
      • adjust the turrets 10″ left/10″ up, shoot a group
      • adjust turrets 20″ right, shoot a group
      • adjust turrets 20″ down, shoot a group
      • adjust turrets 20″ left, shoot a group
      • adjust turrets 10″ right/10″ up, shoot a group
      • the target should have 2 groups at the bullseye, and a group at 4 corners of a box around the bullseye
    • If possible, pick a longer distance and shoot a group. Verify that the point-of-impact matches your ballistic data. For instance, if you zeroed in at 100 yards, and your ballistic data shows that the round should hit 2″ low at 200 yards, then your group should be close to 2″ low at 200 yards. Repeat, if possible, at other, longer distances.

If your scope does not hold true during the “boxing”, you probably have some issues with the scope internals and you need to replace the scope or return it to be serviced. If your rounds are hitting significantly “off” of the projected ballistic calculations, you may have inconsistent loads (try using some match grade rounds), or your gun configuration may need some precision work.

Not Grouping?

If your gun does not hold the zero or have reasonable groups over 2-3 group checks, then you probably have a functional problem with your gun. Generally, the order I would look for the issue would be as follows:

  1. Check the scope mountings – rings and/or base could be loose or unevenly tightened.
  2. Check out the ammo (it could be bad)  – if you bought the $2 a box ammunition for your rifle and the normal cost of your ammunition is $2 a round, then I would try buying some of the not-so-cheapo ammunition and retry before you start digging into anything else.
  3. Check the gun fittings (they could be loose) – check the stock, bedding, screws, etc. and make sure nothing is loose.
  4. Check the barrel profile/heat – you could have a thin profile barrel that you are shooting too hot of a round through. For instance, I owned a Tikka T3 300 Win Mag with a thin barrel profile. During the winter it shot fine, whereas during the summer it would throw flingers.
  5. Check the barrel:  Is it clean/too clean/worn?  Yes,I said too clean! I know it sounds weird, and I have never had it happen to me, but occasionally barrels will actually shoot better if they are fouled! Eventually, they will get over-fouled, but some fouling helps. That said, generally fouling will lead to bad groups.

Summary

Sighting-in a rifle is critical to using it effectively. It does not have to be a chore every time you sight-in your rifle. Sometimes, just quickly sighting-in or verifying a sight-in is all that needs to be accomplished. Other times, a simple point blank zero will work for the rifle, saving the extensive full workup. When you need to know a rifle will be ballistically accurate for a load, you have to do a full workup. When your rifle requires a full workup, it is important that you invest the time do a thorough job.

Leave a comment

Your email address will not be published. Required fields are marked *

Time limit is exhausted. Please reload CAPTCHA.