*Optical phenomenon* or a curved barrel - pellet flight starts off center - SOLVED

[Adop]

I was setting up my OrionCam with firefly (10/10 recommend) when I noticed the pellet first comes into frame far to the right (further than the windage). I am shooting JSB 15.89grs at 914 fps from a Daystate Regal XL with Hawke Sidewinder 4-16x SFP scope with half mil ticks (true mil at 10x), mounted on UTG medium rings. Two clips below.

Clip 1: Shooting paper at 20 yards with a 20 yard zero, very little wind, 10x magnification. The pellet enters frame about 2 mils to the right, I thought it was scope cant and realigned the scope. The scope cam wasn't lined up or focused properly yet so ignore the tilt in the video.

Clip 2: A different day. I zeroed at 20 yards and dialed 0.7 mils up and 0.5 mils left to shoot the target at 50 yards. The wind was spiraling but the shots were consistent once dialed in. I don't remember if I was shooting at 10x or 14x magnification in this video, so here's the math for all of it: Pellet enters frame 4 mils to the right - at 10x this suggests I either misjudged the wind by 22 mph and was dialed 4 mils not 0.5, or there's a ~20 degree cant in the scope, neither of which are true. If this video was taken at 15x, that would translate to the pellet starting 2.7 mils right on a 10x magnification, which mean I misjudged the wind by 15 mph..

Anyone know what's going on here?


PS: I'm still getting the camera focused in these clips so don't judge the quality - the scope cam is great

 

[Adop]

The reason you were experiencing that phenomenon was because although the parallax at the target's distance was corrected, the camera lens wasn't looking through the scope at its center. You can easily observe this by removing the camera and looking through the scope yourself. First, focus on a target, say 30 yards, and make sure there are objects much closer than the target that can also be a part of the sight picture for reference. Then, move your head side to side while looking through your scope but at the same time paying attention to the out-of-focus objects before the focused target--you would see them move off center. So if you think of your camera's lens as your eye instead at the time of the video recording, therefore, your eyes or line of sight wasn't concentric with the ocular lens.

If I kept the scope mounted the same, set the parallax to 20 yards with a marker in the line of site at 20 yards, and then shot the target at 50 yards - the camera should show the pellet pass center reticle at the 20 yard mark (which would not appear to be on target at 50) before hitting the target at 50 right? I could also do this test since its a side mount camera.

 

[spinj]

The pellet coming from the right and converging with the point of aim is as I stated in my post--because the region from where it appears and just right before it converges in the sight picture is where parallax exists in relation to the angle at which your camera is mounted. As shown in the video, parallax error diminishes as the pellet travels to the point of aim. That is why I advised that you test it yourself by doing what I prescribed. From what we are seeing, and I suppose you did before taking the shot, parallax was corrected at the target's distance. That is why, as strange as it appears, the pellet magically hits at the point of aim. I am sharing this as I've experienced the same in the past.

As long as you did your due diligence by aligning the vertical strand of your scope's reticle to the bore's axis and shoot your gun level this phenomena shouldn't be a problem provided your shooting technique is spot on and that your point of aim is corrected for parallax if you choose to continue using a scope cam. But it's better to shoot looking directly through the scope, in my opinion, because its easier to keep your line of sight to the scope's. When I do this, the pellets fly along the vertical strand of the reticle.

 

[Bobbybeef]

if you are going to fast the pellet cork screw

 

[Adop]

We have a winner for the cause of this phenomenon! @spinj was correct in that the camera wasn't lined up perfectly down the scope but had a correct parallax, shifting where the pellet "appeared" to be in the scope until it hit the target at the focus range.

The reason you were experiencing that phenomenon was because although the parallax at the target's distance was corrected, the camera lens wasn't looking through the scope at its center. You can easily observe this by removing the camera and looking through the scope yourself. First, focus on a target, say 30 yards, and make sure there are objects much closer than the target that can also be a part of the sight picture for reference. Then, move your head side to side while looking through your scope but at the same time paying attention to the out-of-focus objects before the focused target--you would see them move off center. So if you think of your camera's lens as your eye instead at the time of the video recording, therefore, your eyes or line of sight wasn't concentric with the ocular lens.

Videos from two tests attached - no wind, same gear, shooting JSB 15.89s same fps:
1) I am aimed at a target 50 yards back with the parallax set to 20 yards, the distance of the closer target. This shot has the same camera alignment as in my original posting. The pellet starts off from the right side, but crosses the crosshair at 20 yards, then hits where I was aiming with my eye properly lined up through the scope (side mount perks).

Videos 2 and 3)
On these I'm manually holding the entire camera mount more to the left. I am a bit unstable holding the rifle all things considered, but the pellet travels perfectly center up and down the crosshair towards the target.. and then past it (my error).

Conclusion: It's optical and I won't subject myself to barrel indexing. The pellets are not spiraling. I can finally move on to making these videos look crisp! You'll also notice that adjusting the camera position cleaned up the diffraction on the left side of the scope. Thanks for the input everyone, it was interesting seeing all of the different theories.

 

[jking]

I haven't indexed it. I'll have to look into how feasible that would be to test with the Daystate Regal. Does this look like a reasonable amount of barrel curve? It feels like a lot..

I don't think you can rotate the barrel on a Regal. Almost positive its one piece so the barrel inlet port orientation can't be changed.