Parallax adjustment

[sand rat]

I have a problem I'm hoping you gentlemen can help. I understand parallax and how important it is. All my scopes have side focus parallax adjustment.

But here is my problem, I've settled in, squeezed the rear bag to get on target, and now I need to adjust parallax. That is when my head pressure on my cheek weld pushes the scope sight picture high and off target when I let go of the rear bag. This is becoming really flustering. To compound the problem C7 vertebra is fused in my neck, so I have a hard time floating my head to keep pressure off the stock.

Any suggestions would be a great help.

Sand rat

 

[Topstrap]

Re: Parallax adjustment

I made oval shaped bags from suede leather of varying sizes and filled them with plastic pellets and made them very firm. Since using these I never use a squeeze bag anymore. Been much more consistent. Roll it till it's close then settle the gun into position then you don't have to keep pressure from your hand to maintain position. Don't have to worry about constantly squeezing as the media inside settles slightly and lets the gun drift off.

Just an idea, been working great for us but hard to get used to if you are used to a squeezy bag.

Topstrap

 

[ShtrRdy]

Re: Parallax adjustment

A couple thoughts:
What if you were to use your trigger hand to control the rear bag while you adjust parallax? Or you can use your rear bag hand to make a little adjustment on the parallax knob, then go back to the rear bag. I think I tend to use the second method - I'm still learning.

 

[sand rat]

Re: Parallax adjustment

I've been thinking about a rear mono pod. This would be solid and wouldn't let the butt drop. But I really dont want to use one, because I here they are slow to use. Then again it might be faster than all the fighting I'm doing at the present time.

 

[Sterling Shooter]

Re: Parallax adjustment

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sand rat</div><div class="ubbcode-body">I have a problem I'm hoping you gentlemen can help. I understand parallax and how important it is. All my scopes have side focus parallax adjustment.

But here is my problem, I've settled in, squeezed the rear bag to get on target, and now I need to adjust parallax. That is when my head pressure on my cheek weld pushes the scope sight picture high and off target when I let go of the rear bag. This is becoming really flustering. To compound the problem C7 vertebra is fused in my neck, so I have a hard time floating my head to keep pressure off the stock.

Any suggestions would be a great help.

Sand rat

</div></div>

You should attempt to adjust NPA for the desired sight picture without squeezing anything. Upon shouldering the rifle, move the entire body, relaxing when the target/sight relationship is as desired from bone/artificial support. No muscular effort should be required to maintain the sight picture as the firing tasks are being executed.

 

[stranded]

Re: Parallax adjustment

^^^^ This. Anything else you can end up with vertical, horizontal, & wtf goupings.Gets hard to diagnost.

 

[Cserv]

Re: Parallax adjustment

Am I doing it wrong by adjusting parallax before settling in for my string? I adjust parallax then my npa and aquire my sight picture. I figure parallax is adjusted according to target range and only changes if engaging multiple ranges. Is this correct?
Eric

 

[Lowlight]

Re: Parallax adjustment

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cserv</div><div class="ubbcode-body">Am I doing it wrong by adjusting parallax before settling in for my string? I adjust parallax then my npa and aquire my sight picture. I figure parallax is adjusted according to target range and only changes if engaging multiple ranges. Is this correct?
Eric</div></div>

yes that is correct, Sterling is an Iron Sight and low magnification shooter and not explaining parallax in the context we use it.

NPA has nothing to do with parallax, the only thing close is establishing your cheek weld first, as cheek weld can have an impact, if not set correctly. What he is saying is, by using the support hand with the rear bag, you are creating muscular tension, which is not right, he doesn''t use a rear bag so he is missing the trick there. You adjust the tension on the rear bag to adjust the height so you can line up on the target. There is really no tension, you just squeeze the bag to reshape it and move it up or down, some of you can leave it that way, some of you just hold it in place, and do not squeeze so hard you cause problems. (although people do develop or have a sympathetic squeeze because of their rear bag technique)

You focus on the target, correct the parallax then adjust your NPA... Parallax is part of sight picture and is done then, not during NPA, you need a sight picture first before you adjust your NPA. Because he is slung, and not using a bipod or rear bag, he adjusts his barrel height in the front, not the back like we do.

 

[Bigwheels]

Re: Parallax adjustment

Here's a question I have never heard answered. Does the elevation, & windage adjustment change the parallax adjustment? In other words, will the adjustment change before the elevation is dialed in vs. after it's dialed in? I have been adjusting the elevation, & then parallax. I think since the reticle moves inside the scope, that should change the parallax adjustment.

 

[Lowlight]

Re: Parallax adjustment

No t really, windage and elevation do not move the reticle forward or backwards enough... though I can see where part of the reticle would be out of parallax a bit if the erector is maxed out. The center should be good... (which is why using hold over reticles on the far edges will sacrifice precision do to distortion.)

Parallax is the relationship between the shooter's eye, the reticle and the target, they need to be on the same focal plane, that is not a left right but front to back.

If changing the elevation or windage changes the parallax I would suggest sending it in for repair. I bet it would be pretty hard to detect, it has to be minimal if it was that visible I would suspect a problem.

Side focus scopes have a focus lens pretty close to the erector.

Ian has images here

 

[hlee]

Re: Parallax adjustment

Because parallax adjustment adjusts the relationship between the focal plane of the target image and that of the reticle (bringing them into the same plane) this adjustment is done perpendicular to the windage and elevation adjustments. And, as it is perpendicular, one should not have an effect on the other.

 

[Sterling Shooter]

Re: Parallax adjustment

OP,

The title is "parallax" but your problem seems to be more to do with position consistency and perspective of aim brought about by your misunderstanding of how to properly use the rear bag for support. I've got to tell ya, most shooter's do not know how to use any sort of artificial rest for proper support; and, thus the support is not the aid it is sought to be. Frank is of course correct in his instruction on how the rear bag should be used for the best results. What I suggest is begin by shouldering the rifle, cognisant for the 5 factors of a steady position but without regard to a target/reticle relationship, just allow NPA to come about for where ever the rifle wants to point. Then, adjust NPA for the target/reticle relationship which is desired. Next, pull trigger smoothly and follow through. Executing the two firing tasks in this step by step procedure will help you to get maximum usefulness from all your aids, ie scope, bipod, and rear bag.

 

[sand rat]

Re: Parallax adjustment

I made up a new rear bag last night, using smaller beads for filler, and stuffing it full. This made the bag harder than my previous one. I also made it an inch taller. Now the rifle sets pretty still. The new bag doesn't have as much fine adjustment, but I think there is plenty, at least the rifle sets still while adjusting parallax.
By rotating the bag form lets say a 45 deg to the 90 deg it looks like I can gross adjust it, and the rifle will set still, and I can adjust parallax without the butt sinking. At least that is what I saw on the living room floor. Now for a range testing.

I pray none of you have to deal with the spinal problems I have to deal with. I have to keep reminding myself each and every shot, buck up be a man and squeeze the trigger.

 

[Topstrap]

Re: Parallax adjustment

I see your location says Midwest, if you're around Ohio you're more than welcome to join us out at Rayners for a practice/tweak day. We usually can go about anytime, they are limited to distances and have steel from 234 to 1000 yards which still keeps it pretty challenging with varying wind directions.

http://www.raynersrange.com/

Topstrap

 

[sand rat]

Re: Parallax adjustment

I sure would like to take you up on that, thanks for the offer. That would be a long drive for me. I'm in Kansas. Finally after a long long years of waiting, one of our shooting sports friends has set up a monthly event on his ranch with different stages each month. We shoot to 1400yrds currently. That stage is always the same, steel plate 16x18in. Starts at 300 progresses to 1400 two shots per target and move on to the next. We usually get in about 4 different stages each match. Long range, movers, hostage, and like last month shooting carbines form a moving vehicle. Different stages each month to keep things interesting.

Started out the year pretty sorry, but have been improving every month by leaps and bounds. Thanks to the guys on Snipers hide. I'm not a bad shot, just not a master shooter.I never will be this late in life, and busted up as I am. But I keep the younger crowed on their toes, so to speak.

 

[Topstrap]

Re: Parallax adjustment

Know what you mean, I'm 58 but in still pretty good shape. Sounds like a great place to shoot, similiar to our matches where we move to different stages and the targets on some stages are different sizes and worth different point values. Lets you gamble some on how small you wish to go for and if it's worth the higher point value. We have old wooden benches and also places for the prone shooters.

Takes about a year to get things figured out then you'll be whoopin butt every match. When I was younger and competing I was told to watch out for the old guys, good chance they have put a lot of rounds downrange and will hand it to you at a match.

Have fun, good luck with next seasons matches.

Topstrap