Charlie Tarac truing. Need some help please

[odoylerules]

So I took out my micro Charlie today to test and calibrate. I need some guidance on how to make the correction calculations. It’s set to 25 mils. I shot a 3 shot group with the scope zeroed, then dialed 25 mils, shot a group, then zeroed it and mounted the Charlie and shot another 3 shot group. This was done at 50 yards. The scope group measured 45 inches up, which is perfect. The Charlie group was 3/4” lower, so 44.25”. I understand there’s a natural offset because of the height difference of the Charlie compared to the scope and that it basically zeros itself out past 200 yards. So is the Charlie group just due to the offset or do I need to calculate a correction into this. The trouble with trying to shoot at 200 yards at 25 mils is the extreme height the zero and 25 mil impacts would be.

 

[MACHTECH]

Message sent.

 

[Yerman]

MACHTEC helped me out too and has some great ideas. My buddy and I used his method, and a variation of a method we came up with and they both worked well.

I built a double thick plywood plate with rubber feet and clamped it to a concrete bench at my local range. Bolted to the plate was my vice and a makeshift rail to hold our scopes. Dialed our elevation and held over to our desired adjustment. For example:

Setting our Charlies to 40 mils, we dialed 35 mils and adjusted the vice so the 5 mil mark was set on an object at about 1000 yards. Without moving the vice or scope, we then dialed back to zero, attached the Charlie, and adjusted the Charlie so the crosshair is in the exact same spot as the 5 mil mark.

One thing to note on the Macro version that attaches to the objective, the rotation of the Charlie has a big impact on the left/right shift of the crosshair. It took a bit of back and forth for us to get both the rotation and elevation dialed in. Not sure how you can make that adjustment on the rail mount version like yours but it's something to check after you get it set up, and adjust if possible.

Top pic below shows a ball head we used at first, but ended up changing it out for the second picture because there was too much play in the ballhead.

Unfortunately I didn't grab a pics of us using it at the range but you get the idea.

Final thought, make sure you follow the screw tightening pattern in the manual. Also, we went 10 in/lbs at a time up to 60in/lb total. Don't freak out that the mirror moves when tightening them down. It all comes back into alignment once you get to 60 in/lbs.

OP, what caliber are you shooting and at what range? Just curious.

 

[MACHTECH]

Wow... Nice set-up Yerman! Mine is a little simpler. Make some kind of fixture to hold the entire rifle or just the scope on one side of your garage.

Then on the opposite wall, snap a plumb line. Put a pin on zero and then dial how ever many mils you want in increment. Then put your CT on and set accordingly. This pic shows pins at zero, 30, 50, 60 and 65 mils.

We made one of our CT's into an adjustable mil model with very fine graduations. After a repeatability test, our average margin of error when adjusting was +/- 3 mils. I don't care how fine or precise you engrave your graduations, these things are touchy! Lol. We ended up scrapping that idea and just bought two more units.

 

[Yerman]

Thanks. I wanted mine to be portable so I could take it to the range and use really far distances thus eliminate any issue with the offset of the mirrors. I don't have a long garage or anywhere that I can use a wall that is far enough to do it right. It works out good. I did double check at home looking through my back slider from my backyard to my front door and the math lines up.

Clamping the base to a concrete table was the key to prevent movement.

 

[Squibbler]

I understand there’s a natural offset because of the height difference of the Charlie compared to the scope and that it basically zeros itself out past 200 yards.
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The collimation lens on the Charlies are pretty forgiving. The variances are within reason. Your Charlie was factory set to 25 mil. But you have shown that on your system (your pic rail, your scope, your mounting method) your Charlie's elevation is actually 24.6 mil. Its your choice if you want to futz with it, or just run it, and know that your elevation is 24.6 mil.

Mine was similar. My factory setting was 30mil. When I tested mine, it proved to be 29.5 mil, on my system.