Instructables

DIY Scope Turret, Bullet Drop Compensator

Picture of DIY Scope Turret, Bullet Drop Compensator
Having a less expensive rifle optic will leave you without a bullet drop compensator. If you want to adjust your scope you will have to go to the range and use the official calibrated American penny, and zero your rifle. Some high end scopes have optional turret adapters, but I have not found any for my cheap NC Star scope. So being an avid DIY'r, I dug through my parts drawer and came up with this combination.

Using an old volume potentiometer and a Radio Shack knob, I build a turret for my scope.

Caution, with any DIY mod you will have to take your time and there is always a chance of ruining your dust cap.

DO NOT MODIFY A LOADED WEAPON, CLEAR YOUR RIFLE AND REMOVE THE OPTIC.
 
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Step 1: Potentiometer

Picture of Potentiometer
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A standard $2 potentiometer has an aluminum shaft; which is machined for a smooth fit. First you will have to remove the shaft from the potentiometer.

Use a small screwdriver to bend the tabs and a pair of needle nose pliers to remove the case.

Step 2: Fit the potentiometer to your dustcap

Picture of Fit the potentiometer to your dustcap
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Since the potentiometer does not fit in the cap, a little filing will have to be done. You can use a bench grinder to a faster results, just try to keep the diameter as close to the cap size as possible.
You will have to drill out the cap to fit the potentiometer base. The best technique is a small pilot hole and a step bit. The step bit will help to center the hole if you are not dead on.

 

Step 3: File for fit

Picture of File for fit
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Since the potentiometer base is a little thick, take a file and rmove some material from the bottom and sides to make the base as flush as possible.

Step 4: Notch the shaft

Picture of Notch the shaft
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Now file the shaft to fit the MOA adjust slot. If you have a vice, clamp the shaft in horizontally, and file sidways to create a notch on each side. Leave the shaft a little thich and then slowly remove material from each side until it fits perfectly. If you remove too much material, the shaft will snap.
mr. clean4 years ago
hey nice job it looks factory i might try this for my airsoft gun itll be way better than removing the stupid dust cap every time (obviously). it feels good to be the first one to comment on an ible ive never had the experience :p