By Mark V. Lonsdale, STTU
I’ve lost count of how many times I’ve been on the range and run into a shooter who was having trouble zeroing his rifle. A good number of these were attributed to the scope being installed incorrectly, and in particular, loose rings or bases. It several cases the action bolts were also loose allowing the action and barrel to jump about in the stock. So let’s look at a few checks you should run when you receive a new rifle, each time you clean the rifle, and before entering a sniper competition or deploying on an operation.
When you receive a new rifle, either factory or custom built, the first thing you should do is remove the barreled action from stock to ensure everything looks good and that the metal to stock fit is of acceptably close tolerance. If it is supposed to be aluminum pillar bedded, then check that the pillars are there. This will affect the toque values for the action bolts. Also check that the trigger has adequate clearance from the stock and that there is not contact points or interference with the safety.
.300 WinMag Mk13 Mod7 clone built on a Stiller’s MK13 action and Bartlein Heavy Palma barrel.
If it has an aftermarket trigger such as Timney, Jewel, or Bix’n Andy, this is the time to set the trigger pull. Keep in mind that some competition triggers can be delivered with the trigger set at about 8 ounces, a fraction of what you may be used to with a factory 4+ pound trigger. A good starting point for a precision sniper rifle would be 2.5 pounds, but consideration should also be given to agency limits on trigger weight.
A convenient feature of the Bix’n Andy Dakota is it can be adjusted without removing the action from the stock
For a Jewel trigger the adjustment is screw #3 in the instructions; for a Timney Calvin Elite it is the lower screw on the front of the trigger frame; for Bix’n Andy it is on the bottom forward of the trigger; but for all, be sure to read the instructions before making adjustments.
Next, replace the barreled action in the stock and torque the action bolts. I use 65 in-lbs for fiberglass stocks with aluminum pillar bedding. A factory wood or plastic stock without pillars could be 35-45 in-lbs, but check with the manufacturers before going gorilla on your action bolts. Next take a business card and run it the length of the barrel between the barrel and the fore-end to ensure that the barrel is fully floated. This also works to get any debris out of the fore-end channel in the field.
Cycle the bolt and trigger to ensure everything is working as expected. Set the safety and pull the trigger to ensure that the safety works; then release the safety to see if the action fires. This has been a recall issue in the past, where rifles could fire when the safety was released.
At this point you can mount and torque the scope rail, rings, and mount the scope. (Separate article) Ensure that the eye-relief is correct and that the scope reticle is vertical and plumbed to the rifle.
Torquing the 1/2″ side nuts on the scope rings
At the Range:
If the rifle has an adjustable cheek rest, set the cheek rest so that your eye lines up perfectly with the scope. Bore sight the rifle at 25 yards, then zero the rifle to shoot about an inch low at 25 yards. This should put you very close to dead on at 100 yards. Once you are zeroed at 100 yards, loosen the turrets and zero them out so that your elevation is “0” and windage “0.” If the scope has a bullet drop compensator, then set the elevation to “1” or “100.”
Zeroing the turret to “0” for 100 yards
Next, you will need to chronograph your ammunition in the this rifle since you will need the muzzle velocity (MV), ballistic coefficient (BC), and scope above bore height to generate a ballistics solutions chart or input the rifle’s data into your Kestrel. Keep in mind that your printed data is only valid for the environmental conditions at the time and elevation when you zeroed the rifle. Changes in temperature and altitude can have a noticeable effect at longer ranges, but the Kestrel will adjust your firing solutions for environmental conditions and wind. For the LE sniper, where distances are statistically short, the environment will have little effect on bullet impact.
.308 Win precision rifle built on a Rem 700 action, Bartlein Heavy Palma barrel in a McMillan A3-5 stock.
Rifle Checks Prior to Competitions or Operations
Any competitor or hunter who travels to compete or hunt will know the importance of checking bolts, screws, and zero after a long trip. The same is true for snipers. Whether driving or flying, screws can vibrate loose and a scope can go out of zero, especially if some ham-fisted baggage handler decides to play shot-put with your rifle case or it falls off the conveyor belt. Many shooters will remove their scopes and hand-carry those, but this also requires re-zeroing at the first opportunity.
Since you cannot depend on someone else to have the correct tools, here are a few suggestions for a small tool kit. When rifle shooting I carry all the Allen wrenches and Torx wrenches to deal with scope rings, rails, bases, and turrets, plus a 1/2″ wrench for the scope ring bolts. With handguns, I carry Allen wrenches and screw drivers for sights and grip screws. Pennies and dimes also see a lot of action with the local shooters zeroing their slot-turret sporting scopes before hunting season. Another option is a set of Fix-it-Sticks.
Just because a rifle is new out of the box or fresh from the custom rifle builder, you cannot assume all screws and bolts are correctly tightened and torqued. And be assured, any looseness defeats the prime principle of accuracy – “Accuracy is the Product of Uniformity.” For a rifle/scope system to perform as expected, there can’t be any inconsistency in fit or torque values. So provided that the rifle system and ammunition meet the standards of uniformity, then the rest is up to the shooter to do his or her part. Uniformity of grip, stock pressure, shooting position, and trigger control are of even greater importance than the rifle. A good shooter with a 1 MOA rifle will out shoot a mediocre shooter with a ½ MOA rifle.
Finally, make a written check list to ensure nothing is missed and keep a written record of all work done on the rifle. As with your sniper data log, these are legal written records that will be called in to review in the event of an operational shooting.