Parallax Issue?

[BuckeyePrecision]

If your parallax is not set right, how far would you expect your POI to shift when you move your head?

The back story is I borrowed my friends Bergara B14R to shoot in a match this weekend because I am out of ammo for my Tikka and it will not shoot CCI SV which is all I have left at the moment. I did not care for his scope so I swapped a Mark5 HD onto it knowing it does not parallax all that well at 50 yards but figuring I could get by with it. I sighted it in off of the bench and was shooting under .5. Before I left I decided to shoot a few off of a barricade and the group shifted 1.5 inches high and .75 right, but still shot a tight group. I went back and forth to check, and sure enough, the POI kept shifting to the exact same places. I was short on time so I did not have time to mess with it any more.
After I got home the only thing I could figure was the parallax was off by quite a bit even though the scope focused well but would you expect that much of a POI shift?

 

[Gjmen22]

If your parallax is not set right, how far would you expect your POI to shift when you move your head?

The back story is I borrowed my friends Bergara B14R to shoot in a match this weekend because I am out of ammo for my Tikka and it will not shoot CCI SV which is all I have left at the moment. I did not care for his scope so I swapped a Mark5 HD onto it knowing it does not parallax all that well at 50 yards but figuring I could get by with it. I sighted it in off of the bench and was shooting under .5. Before I left I decided to shoot a few off of a barricade and the group shifted 1.5 inches high and .75 right, but still shot a tight group. I went back and forth to check, and sure enough, the POI kept shifting to the exact same places. I was short on time so I did not have time to mess with it any more.
After I got home the only thing I could figure was the parallax was off by quite a bit even though the scope focused well but would you expect that much of a POI shift?

My guess is it isn't the parallax setting. How was the gun resting when you were shooting off the bench? Bipod? I'm guessing there is some type of torque being applied differently from the bench and the barricade. Check the rifle over good. Look to see if the barrel is touching the stock at different positions and make sure the action is torqued properly.

Gjmen22

 

[BuckeyePrecision]

I just replaced the trigger for him, torqued it back down and just now checked it again so I know that is good. When he first bought it I looked it over close and checked that the barrel cleared the stock everywhere while it was at rest, I have never checked it with the bipod loaded so I will have to check that out tonight.

 

[Near miss]

How good cheek weld did you get?
Was it comfortable?
Consistent?

 

[jbell]

The 4 MK5 5-25 scopes I have owned all have completely corrected parallax down to about 32-35 yards, so I anticipate yours should also. However if parallax is off the POI shift will be determined by how far your head is out of alignment with the center of the scope and how far you are shooting. Meaning, it is hard to say how much of a POI shift you will get.

 

[BuckeyePrecision]

I spent a little time at the range yesterday playing around with it and I am starting to believe it is a combination of issues. The parallax was part of it, the scope was clear, but if i moved my head position I could see the crosshairs moving around the bull. I switched out the Mark 5 for a Viper Gen II that I know is good at 50 yards and it was hitting closer to where it should, but still a bit high when off the barricade compared to the bipod. I tried shooting the rifle without loading the bipod at all, hit high and the same place as off the barricade. I double checked all of the torque settings and they are good and the barrel does not touch the channel loaded or unloaded. I have to assume at this point it is a bedding issue.

Last ditch effort to prove what I think the issue is I am going to swap it into the Bravo off of my centerfire and try again.

 

[Gleedus]

I expect it has more to do with the position change then anything else. 1-1/2" shift due to parallax wouldnt be possible at 75 vs 50 yards.
If you have the buttstock set incorrectly for positional shooting you can create more movement then you may expect. Also your grip especially with a "soft" fore end.
Parallax maybe adding to it if your cheek piece is set wrong.

 

[OneMoreNoMore]

Rifles Only Accuracy podcast had a leupold employee (Michael) that explains how parallax effects close range more than long range.

 

[PowellSixO]

Rifles Only Accuracy podcast had a leupold employee (Michael) that explains how parallax effects close range more than long range.

I agree a lot with that statement. I can move a group an inch easy with parallax set even just a little off at 50 yards. Here’s a perfect example from my last time out. My first groups were with cci, and the targets on the right. I thought I had the parallax set correctly but I didn’t. Every group was right. I adjusted it and everything went back to normal.

 

[Williwaw]

Rifles Only Accuracy podcast had a leupold employee (Michael) that explains how parallax effects close range more than long range.

Referring to that podcast here is the math as they presented it. If your parallax is out by a factor of two you can miss by half of your objective diameter. IE. set at 25 yds, shooting 50 yds, 50 mm objective ....equals 25mm miss maximum, that is an inch. Use percentages to calculate your mileage and it will be close.