This report covers:
- Simple and complex
- The test
- Six-power group
- Why did this happen?
- 12-power group
- I saw it
- Teaching point 1
- Teaching point 2
I will open with the results of today’s test summed up in two words — holy moly!
Simple and complex
Remember what we are testing. We want to see whether adjusting the magnification of a second focal plane (SFP) scope has any affect on where the pellets go. Today I’m shooting Goldie with the Meopta 3-15X50 RD MeoSport SFP scope that is already sighted in at 25 yards.
Today’s test sounds very simple — shoot one 10-shot group at a target with the scope set on 6 power; shoot a second 10-shot group at a different target with the scope set on 12 power. It sounds so simple. It was anything but!
Today’s test was one suggested by Machiavelli, excuse me, by reader pacoinohio. He said,
“A suggestion for scope testing- (1)- two targets, two groups. One group at 2x and the other at 12x. One shot at 2x and then crank it up to 12x for shot two on the second bull. Repeat until you have two ten shot groups.
Sounds simple, right? Well, it isn’t! I first put 10 pellets into each of two piles. Didn’t want to shortchange any group! Then I realized that I had to separate the pellet piles so I didn’t double dip as I was shooting. So the 6X pellet pile went on the left and the 12X pellet pile went on the right side of my shooting bench.
I also separated the targets the same left and right as you will see in a bit. But it doesn’t end there. Remember, I had my cataracts removed and I can no longer see up close. I had to put on my glasses for each change of scope power. I wanted this test to be as precise as possible.
I shot 10-shot groups from 25 yards with the rifle resting on the sandbag. I used the most accurate pellet for Goldie which we learned in Part 5 of BB’s Goldie is the JSB Exact Jumbo Monster Redesigned. After each shot I changed the magnification of the scope and switched to the other target.
In Part 5 of BB’s Goldie the rifle put 10 Monster Redesigned pellets into a 0.154-inch group at 25 yards. I figured that with all the switching around today’s groups would be a trifle larger, but I had no idea of what was in store!
It took me the entire test to shoot this group because every other shot was taken at 12 power at a different target. The first two shots at 6 power went into nearly the same hole and I was off to the races. Shot three opened the group slightly, but as the test progressed the group kept getting larger for a valid reason that I will share in a moment.
At the end of the six-power test Goldie had put 10 Monster Redesigned pellets into 0.795-inches to my utter shame. One lone shot opened the group that big, but the remaining 9 are in 0.431-inches. While that is better, Goldie is capable of so much more!
Why did this happen?
Remember Part 2 of Rifle stocks? Remember the discussion we’ve been having on cheek weld? When I looked through the Meopta scope for the first shot in this test, the image was dark around the edges. I didn’t have the scope positioned correctly for my sighting eye! Oh, oh. Bad BB!
I could have stopped the test and repositioned the scope, but I didn’t. However (yep — there’s a however coming) when I switched to 12 power on the scope I saw on shot number three (which was the 6th shot of the test) that my cheek weld did matter. I’ll cover that in the discussion of the next group.
The first shot on the 12-power target struck the target paper almost one inch lower and away from where the first shot at 6-power hit. I was amazed. Apparently the guys who say changing the magnification on an SFP scope were correct. It makes a HUGE difference? And when the second pellet landed in almost the same place, I was nearly convinced. But the third shot hit much higher. It hit almost where the 6-power pellets were hitting, but just a little lower. The next two pellets went into this higher hole and I thought, okay, that’s in nearly the same place as the 6-power pellets. Then I saw it.
I saw it
Two groups were forming, one low and the other high. That is indicative of an inconsistent cheek weld. The lessons of all I have written on rifle stocks in the past month were coming back to slap me in the face!
There were now 5 shots in this group and 11 shots in the test — the halfway point. And the main group was forming higher on the target — almost as high as the 6-power group. But the 6th shot in this 12-power group hit down low with the first two shots, giving me two groups with three shots each in this 12-power group.
Do you begin to see how complex this test is? I watched the two target groups form and even I was confused!
When I finished, the 10 shots at 12 power had grouped in 0.654-inches between centers at 25 yards. It’s much larger than BB’s Goldie should shoot.
BB’s Goldie put 10 Monster Redesigned pellets into a 0.654-inch group at 25 yards. This group looks like one homogenous group, but until the last two shots, it was two separate groups, a small one down low and a larger one up high.
Teaching point 1
I shouldn’t have to say it but this test makes it clear that your cheek weld is extremely important to accuracy. And if some readers want to call that consistency, I won’t argue the point.
Teaching point 2
But there is more. After the test when I photographed the targets I noticed that the 6-power group was slightly higher on its target than the group shot at 12 power. So I took another picture to show you. I marked each group where I thought the center was, then I drew two lines between the groups to show the height of the group centers on the target. Let’s look at that picture now and you’ll see what I mean.
Here are the two groups as they were shot. The group shot at 6 power is on the left. The two lines are drawn from where I estimated the centers of the two groups to be.The higher line comes from the center of the 6-power group.
The photo above shows us something of interest. It shows that the center of the group shot on 6 power is slightly higher on the paper than the center of the group shot on 12 power. There is a lot of guessing in all of this. For example, how far down does that single shot in the 6-power group drag the center of the entire group?
The way I have marked it, the center of the 6-power group is about 3/16-inch (4.67mm) higher than the center of the group shot on 12 power. With all the guessing can anything be said about these two groups? I believe it can.
You may not agree with where I marked the group centers but it’s obvious the group on the left is higher than the group on the right.
Does this test prove anything? Probably not. One group at each magnification isn’t conclusive. But it is an indication that adjusting the power in an SFP scope does change the point of impact. And guess what. We will see this test again. Next time I will adjust the mounting of the Meopta scope until I have it adjusted correctly for my cheek weld on Goldie and I’ll run this same test a second time.
Since I need to remount this scope anyway my plan is to conduct the test of the first focal plane (FFP) Integrix scope next and then come back to this one after that. That way we will get a chance to look at how much a proper cheek weld really affects things. And of course I’m going to mount the Integrix scope so my cheek weld isn’t an issue with it.
One last thing. What does adjusting the scope between shots prove? Nothing, I think. I want to shoot all 10 shots at one power and then all 10 shots at the second power. That gives me, the shooter, a chance to settle down with a single sight picture for each group. I do think doing it the other way was why today’s groups were so large. Since I plan to re-test with the Meopta scope anyway this shouldn’t prove to be a problem.
This is an interesting test, but we are far from finished. So hold your final opinions until all the data are in. Oh, and — holy moly!