15 Apr What you Need to Know about Custom Scope Turrets
Custom scope turrets are all the rage. And, we like them a lot.
However, there are two very key elements to getting an accurate custom turret.
1. Ballistic Data: Your turret will only be as good as the data it is based on.
The most common way to do this is to chronograph your ammunition to get a good average velocity, enter the elevation and temperature that best fits your hunting locations, enter your sight height over bore, bullet ballistic coefficient and what distance you are “zeroed” for. This is how we build your turret for Swarovski Z5, Z6, Z8, and X5 scopes and how we program the Swarovski DS scope.
The absolute best way to build a turret is to true your rifle by shooting your preferred ammo at long range targets and recording the actual click counts needed for each distance. Doing this eliminates errors caused by overstated ballistic coefficients or errors in ballistic models. Then, you can confirm that the proposed click counts on the turret, match your data.
2. Sight in distance: We strongly encourage basing your turret on a 100 yard zero.
With any of our rifles, you should be able to hit the exact center bullseye at 100 yards. With this level of precision in your zero, the turret calculations will be more accurate down range. If you base the turret on a 200 yard zero and sight in at 200 yards, your zero is less precise because your group size is larger at 200 that it is at 100. If you sight in high at 100 yards to achieve your 200 yard zero, you are still relying on a ballistic assumption that may not be perfect down range. For instance, if the data calls for 1.7” high at 100 yards for a 200 yard zero, but the true measure is 1.78” high, you have introduced an error into your data. Any error in your zero is magnified the farther you shoot. If you want a 200 yard zero, just dial your turret from 100 to 200 yards. That is what it is there for! Many people think they are adding 100 yards to their turret range by sighting in at 200 instead of 100. This is false. This typically only adds about 50 yards to your turret capability.
- Even from the same box, ammo velocity varies shot to shot. It is very common to see velocity spreads in excess of 30 feet per second in premium factory ammunition and handloads. This will affect how high or low you hit your target at longer ranges.
- It is not uncommon to see average velocity change by 50 feet per second or more from one lot of ammunition to another. Some, brands are better about this than others, but the potential is always there. It is a good idea to chronograph your ammunition if the lot number changes. If the velocity of the new lot is substantially different, you need to build a new turret. With the new Swarovski DS scope, you would simply change the velocity in your DS App and send this new data to your DS scope, which is a lot easier than getting a new turret.
- Elevation and temperature changes do affect the accuracy of your turret. While small changes are not dramatic, major changes in elevation and/or temperature will reduce your turret’s accuracy at longer ranges. Swarovski’s DS scope solves this issue with built in environmentals.
- After dialing your turret for a longer shot, always remember to dial back down to your zero. People often forget to do this and miss their next 200-yard shot because their turret is still on 650. The DS scope solves this problem too!
Adding a custom turret and rangefinder to your gear will extend your ethical shooting range but don’t let that yardage number make you overconfident. Solid shooting fundamentals are still just as important. Keep practicing!