Crosman sight system
The Crosman Precision Diopter Sight System.

Part 1
Part 2

This report covers:

  • The test
  • Here we go
  • Elevate the sight
  • Cant the rear sight
  • Cant right
  • What happened?
  • What to do?
  • What have we learned?
  • Summary

Today I do it. I intentionally cant the rear Crosman Precision Diopter sight to see whether that has any affect on the point of impact downrange. Some readers have said if we sight through two holes cant shouldn’t be an issue. We shall see.

The test

To get the greatest separation between groups , if there is any, I shot today’s test from 25 yards. I shot from a bench with the rifle resting directly on a sandbag. I shot 5-shot groups because that’s all it takes to see this.

There won’t be any group measurements today. That’s not what this is about. It’s about whether canting affects the placement of the group when the rear peep sight and a diopter in the front are used. How can two holes be tilted? Some say there will be effects you can see and others say no.

All the shots will be with the Qiang Yuan Training pellet. The Crosman Challenger 2009 likes that pellet a lot.

As I cant the rear sight I will do nothing to the front sight. Remember there are another set of inserts that permit canting the front sight insert just like the rear sight. I am not using them for this test. I’m using the inserts that remain fixed, so as I cant the rifle I’ll see the crossbars that hold the front aperture become tilted against the target.

Here we go

I decided to shoot the first 5 shots with the sights set where they were for the last test in Part 2. They landed in a vertical group at the bottom of the bull. I have no explanation for the verticality of the group, other than the shot at the bottom is what makes it vertical. Take that one away and the group looks more roundish.

Elevate the sight

After the first group I dialed in 40 clicks of up adjustment. That took the next five shots straight up to the top of the bull. That group went up just less that 2 inches.

Crosman Precision sight centered
The first two groups were shot with the rear sight centered in its holder. In other words, not canted.

Cant the rear sight

Then I canted the rear sight to the left. All it took was loosening the one Allen screw that clamped the rear sight “barrel” and then rotating the sight. The sight only rotates as far as the lines on the sight barrel.

This time the five shots went to the left of the last group, the one that is 40 clicks up from the first group. But they didn’t land lower on the target (than the last group fired) as I expected. I also found myself intentionally trying to cant the rifle back to the right to level the bar that holds the front aperture. You will notice that this third group is especially large. That’s from me not canting the rifle that same amount each time. Phooey!

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Cant right

Next I canted the rear sight to the right, which works the same as the left, only in the opposite direction. This time I took pictures for you. 

Crosman Precision sight canted right
The rear sight is canted to the right.

Crosman Precision sight canted straight on
This is what it looks like straight on when the sight is canted to the right.

What happened?

Well, this time I decided to level the front aperture one every shot. I did so because I now knew I couldn’t get it canted correctly (the same) for every shot. And this time all the shots went to more-or-less the same place as when the sight was elevated by 40 clicks. In other words, they DID NOT move to the right as some of us expected them to — at least not very much.

Enough talk. Let’s look at the target.

Crosman Precision sight first target
First target. Here’s whatcha got. First five shots are at the bottom of the bull. Then 40 clicks up and the next 5 are straight up from that. They’re the holes to the left of the big group at the top of the target. Then I canted the rear sight to the left and five shots hit to the left of the bull in a very large and open group. Finally I canted all the way to the right and five more shots are at the very top of the bull. Yes, there is a little separation between those shots and the second five shots, but not that much! In fact one of the holes from the second five shots is inside this final group to the right.

What to do?

BB was puzzled on just how to proceed. But the one thing he knew he could do well is level the front sight insert bar every time he shot. That is what he did on the second target. He started by shooting five shots with the rear sight canted to the right (while leveling the insert bar), as it was at the end of the last target. Then he rotated it to the left and fired five more shots, being careful to level the front sight insert bar for every one of them. Then he centered the rear sight as it had been at the start of today’s test and fired five move shots. And finally he lowered the elevation by 40 clicks straight down. Let’s look at that target.

Crosman Precision sight second target
The second target is telling because I leveled the front sight insert bar on every shot. There are 15 shots in that group at the top. Why the group at the bottom is over to the left instead of at the center on the bull, left and right, I have no idea. 

What have we learned?

I believe that we have learned that the people who said two holes cannot be canted with each other were right. However, I’m not certain of that. 

I also know that when I see the front sight bar tilted against the target there is a natural tendency to level it. The bottom line is, I think this feature of being able to cant the Crosman Precision Diopter Sight System isn’t one I care for. I won’t go so far as to call it a failure, but it isn’t a feature I would ever use.

I didn’t try this with the front sight inserts that also cant with the rear sight. From what I see here as long as the front sight appears level, the pellets go to the same place. Yes, canting the rifle (front sight) does move the shots, but it’s not as clear and precise as when shooting with a scope that’s canted.

Maybe I’m missing something and need to be instructed. That is a distinct possibility. But for now, at least, I will shoot with the rear sight leveled, side-to-side.


Wow! This is a result I would not have predicted. I sided with the ones who thought that canting left and right would move the groups from side-to-side. And I admit that they did move, but the way I did the test it’s too difficult to maintain the same degree of cant every time.

Do I need to repeat the cant test that I did years ago with a scope? I think I know why that test turned out as it did, but first I’d like to hear from you.