This report covers:
- The results so far
- Things done wrong
- Mounted the scope
- The test
- 10 shots 6X
- 10 shots 12X
- The verdict
Okay, guys — this one has been a long time coming. We are testing whether there is any truth in what some people believe — that the point of impact shifts when the magnification of a variable second focal plane (SFP) scope is changed, while it remains the same when the magnification of a variable first focal plane (FFP) scope is changed.
Today we will mount the Meopta 3-15X50 RD MeoSport second focal plane (SFP) scope on BB’s Goldie to run the low-power and high-power test again, to see whether the point of impact changes as the power changes. We are doing that because in the previous test of the SFP scope some mistakes were made.
The results so far
So far the FFP scope grouped in two different locations. That’s what everyone said the SFP scopes would do. The SFP scope also grouped in two locations but I want to rerun the SFP test because of several things I did wrong in the first test.
Things done wrong
The first thing I did wrong was adjust the power of the scope for every shot. As you recall I ran the scope at 6 power and at 12 power so both the Meopta SFP and the Integrix FFP could be tested equally. Reader pacoinohio, who suggested this test, had suggested running the scopes at 2 power and 12 power, but the reticle in the FFP scope was too small to see at 2 power. So I ran both scopes at 6X and 12X. However adjusting the scope with every shot was unnecessary and a waste of time. So this time I will shoot all 10 shots at 6X and all 10 at 12X.
The center of the group shot at 6 power was higher than the center of the group shot at the 12 power. The amount of separation for both the FFP and the SFP scopes was almost exactly the same, with the FFP scope separating very slightly more. That result was the opposite of what people said to expect.
The second thing I did wrong was PROBABLY shooting the test with the Meopta scope with the wrong pellet. I was supposed to use JSB Jumbo Monster Redesigned pellets, but the ones I found on my desk after the first test were JSB Jumbo Monsters. I don’t know for certain that I used those pellets in the test, but there is a good chance I used them and not the ones I used for the Integrix test.
The third thing I did wrong was the placement of the scope on the rifle. Both the Meopta and Integrix scopes are EXTREMELY particular how far the eyepiece is away from the shooter’s eye. Too far from the eye and you get a dark ring around the target. I got that with the Meopta, so I was more careful when I mounted the Integrix to get it right. I also put a folded cloth on Goldie’s raised cheekpiece when I shot with the Integrix, just for better eye positioning, and I want to do that for the Meopta, as well.
Mounted the scope
I took the Integrix scope off Goldie and mounted the Meopta scope, and this time the eye relief was right. The installation was straightforward and no problems were encountered. Then I sighted in the new scope. It took 4 shots to get on target at 25 yards and I shot three more pellets to confirm the rifle was grouping.
The test was shot off a sandbag rest at 25 yards. I illuminated the reticle which is just a center dot. I shot one group of 10 pellets at each power setting of the scope. The goal of the test is to see whether there is a difference in the point of impact of groups fired at different power levels.
10 shots 6X
After sight-in I shot 10 shots at 6 power. They made a 25-yard group that measures 0.46-inches between centers. It’s larger than I would like to see, but it’s not bad for 25 yards.
10 shots 12X
Now I increased the magnification to 12 power and shot a second group of 10. This group measures 0.382-inches between the centers of the two shots farthest apart. It’s 0.078-inches smaller than the first group. It would even be smaller if the last shot had not strayed to the right.
I think it was just easier to see the target at 12 power, which is why the group shot with the higher magnification is smaller. But are the groups in the same place?
With the scope set up correctly there isn’t much difference in where the centers of the two groups are. I measure the center of the 12-power group at 0.121-inches (3.07mm) lower than the center of the 6-power group. But that is just my best guess where the centers of the two groups are.
It was interesting that in all tests the 12-power groups were always smaller than the 6-power groups.
From the little testing I’ve done it seems that the difference in point of impact when variable powers are changed is just an urban legend. If there is any truth to this, my testing indicated the groups shift the least with second focal plane scopes. But as I said, I don’t think there is really much of a difference.
My guess is that those who believe there is a difference will want more testing done at longer distances. As for me, I prefer to shoot a second focal plane scope because the reticle remains the same size at all magnifications.
If these results are not satisfactory, I suggest that anyone who wants more proof conduct tests on their own and report the results to us in a guest blog.