Rifle Scopes Reticle tracking against a wall vs. firing shots...?

[PabloM]

I wanted to check the tracking on a few scopes I have, but didn't have an opportunity to make it to the range... So I decided to try tracking them against a wall in my living room. I'm sure I'm not the first to do this, but I did a quick search and I didn't see any info about doing this anywhere else. So I figured I would share it here, and risk the criticism.

I made a simple mount with a piece of plywood and a section of pic rail, attached a scope mount to it, put a scope in it, and clamped it to a counter top in the kitchen. Then I measured the distance to the wall and did the math to find out the vertical distance that corresponded to 1mil. Then I used a set of digital calipers to plot out a grid, taped it to the wall, and I was able to check tracking in my living room.

So before I get crucified for not doing a real tall target test on the range, I offer these points:

1. My grid isn't perfect, but based on 0.1 mil clicks they're good to about half of that, or 0.05 mils. And the pencil lines are thin enough that they are about the same, 0.05 mils. So it's easy to see very small alignment issues.
2. Conversely, when you shoot a tall target test at 100 yards you are dealing with bigger variables... Wind and atmospheric conditions are factors, but even if you dial those out with a solid zero at 100 yards, the group measurement itself is a variable. If you shoot 1" groups at 100 Yards, that's a spread of 0.28 mils, or 0.14 to the center of the group. How many shots do you fire? What about "fliers" being included or excluded?
3. What I'm seeing is that you can do the math and draw the grid tighter than you can shoot 1" groups, even 1/2" groups. And checking the tracking on my scope I could easily see the reticle move each 0.1 mil.

I've attached a few photos of the setup. I'll admit in the reticle photo I failed to take a picture with the reticle perfectly aligned... I was in a rush to get it wrapped up and I loosened a clamp before I took a picture, so I re-clamped and didn't set it to a perfect zero. But you can at least see in the photo my grid setup is pretty darned good... All of the elevation lines are consistently at the bottoms of the diamonds and the windage lines on the right of the diamonds. Not bad for doing it by hand when the lines were only 0.2896" apart to represent 1 mil where the scope was 24' - 1 5/8" from the wall. I also admit the SS 3-15x42 scope with it's 6M parallax made this easy. Scopes with 50 yard parallax won't be as convenient, but you could still do it maybe just not in your house or back yard.

So I'd like to hear opinions on this method, and what's good and bad about it. I think if you're careful it's a perfectly legit way to check tracking, since it's looking at the scope's mechanics and takes that variable of firing rounds out of the equation. What am I overlooking?

 

[beetroot]

Nothing wrong with what you have done, most folk do something very similar albeit at much further distances, as very few scopes focus that close.

The advantage clamping the scope like you have is you avoid any shooting errors or errors due to weather conditions.
The downside too using a mount as you have is that it can be very difficult to get a good solid mount that doesn't bounce around everytime you move the turrets. But your kitchen bench would be as solid as they come.

 

[ShtrRdy]

Good idea! How close does your scope focus down to?

 

[JMcBurn]

I do that when mounting my scope to the rifle, by putting the rifle in a tripod and using an indoor dryfire adapter.

Thanks

 

[PabloM]

This particular scope goes down to 6 meters so about 20 feet. My other scope is 10 M or about 33 feet. But many scopes lowest focus is a lot more, 50 or 100 yards, so that would be tough to do in a normal house. But you could still put a scope in a mount of some kind and do this on your street. Unless your neighborhood is cool doing it with the scope mounted to a rifle might get you in trouble, quick.