When is an adjustable parallax scope necessary?

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gunsrfun1

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I recently bought a bolt action .223 that I plan to try to get some distance on. The longest nearby range is 300 yards, so that is going to be my max (for now).

I have an AR that I shoot out to 200 yards, topped with a 2-7 scope pre-set at 100 yards parallax. No problems with parallax at that range, that I can tell.

I have a Vortex Crossfire 4-12 scope that I can probably use on the bolt action. It's also set at pre-set at 100 yards parallax. However, I am thinking of buying a Burris E1 Fullfield 4.5-14, for the extra bit of magnification and the more precise reticle. Plus, it has adjustable parallax. Also considering a Vortex Crossfire 4-16 with adjustable parallax.

My question: At what range does an adjustable parallax come in handy? Once I go to 300-500 yards, is the adjustable parallax a necessary item, or can I stick with a scope pre-set at 100 yards parallax?

Thanks
 
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Using an online parallax error calculator, a 40mm objective set at 100 shooting at 300 will have a maximum parallax error of +/-1.575” of error. So shifting full right vs full left in the eye box would mean adding a full MOA to your group size due to parallax error.
 
Sorry, you're talking a bit over my head. Are you saying that at 300 yards I would be off by up to 3 inches, right? So basically my POA (point of aim) at 300 yards could have a POI (point of impact) up to 3 inches off?
Thanks
 
You could “be off” by up to 1.575” in any direction due to parallax error at 300 yards. But one shot could be off left and the next shot off that far to the right, so your total spread in a group due to parallax error could be an extra 3” of group size. For a single shot, you could be up to 1.575” off of desired center.
 
All scopes with fixed focus have, by necessity, fixed parallax, too. This is compensated for with either an adjustable objective lens or a side focus. I have and use both and find I prefer the side focus.
If you look through the scope at, say 200 or 300 yards (not the parallax distance of the scope), and you shift your head while doing so, you will see the reticle appear to move on the target. Bob your head and the reticle bounces, too. With a side focus or AO, if you move the adjustments while bobbing your head you will see the movement of the reticle slow and, when you hit the right spot, stop all together. That is when the parallax is corrected. AND NOT NECESSARILY WHEN THE IMAGE IS IN PERFECT FOCUS! Perfect focus can be affected by a lot of things, not the least of which can be your eyes or corrective lenses. So correct the "moving" reticle. If the image is slightly out of focus, so be it. That's my take on it. and worth everything you paid for it...:scrutiny::D

Because I compete in High Power (and Smallbore) Silhouette, being able to adjust the focus (parallax) is very important. With all rounds fired offhand without support, a small parallax error on the 500 meter rams could easily be a clean miss. Especially for me as I am only an 'A' Class shooter and am happy to hit the steel. (The Master Class guys can usually tell you where they hit the animal!)
And yes, not being able to adjust the parallax can, and probably will, affect your groups at any distance that is NOT at the fixed parallax distance of the scope.

I hope this helps.
 
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If you just look through the center of the scope it matters none at all. I have some of both types. As long as I'm using good technique I can't see any difference.
 
Got it, thanks all of you. So basically, with a scope with fixed parallax of 100 yards, the further away I get from 100 yards, the worse things will get (potentially) as far as POA/POI. I've got a couple "100-yard parallax" scopes that seem to serve me well up to 200 yards (one on my AR as mentioned above, and one on a hunting rifle). Both are "minute of gong" at 200 yards. But I have never gone further than that with either rifle. As jmr notes, I do try to look through the center of the scope, so that helps
However, since I want this new rifle to be a "precision" rifle to some extent, it sounds like I should mount a scope with adjustable parallax, just for some extra assurance.
Let me know if I have missed anything.
Thanks again.
 
gunsrfun1 said:
Got it, thanks all of you. So basically, with a scope with fixed parallax of 100 yards, the further away I get from 100 yards, the worse things will get (potentially) as far as POA/POI. I've got a couple "100-yard parallax" scopes that seem to serve me well up to 200 yards (one on my AR as mentioned above, and one on a hunting rifle). Both are "minute of gong" at 200 yards. But I have never gone further than that with either rifle. As jmr notes, I do try to look through the center of the scope, so that helps
However, since I want this new rifle to be a "precision" rifle to some extent, it sounds like I should mount a scope with adjustable parallax, just for some extra assurance.
Let me know if I have missed anything.
Thanks again.
Click to expand...
Kinda, if your shooting at the distance where the fixed parallax is set, you can be off on your technique, and still make POA hits. Anywhere outside that setting, you can still hit POA, if you are looking dead center through your scope, or have a way of dialing out the parallax by either a side focus or AO.
 
jmr40 said:
If you just look through the center of the scope it matters none at all. I have some of both types. As long as I'm using good technique I can't see any difference.
Click to expand...
Setting the scope distance from the eye, so the full view is visible from normal scope-to-eye distance, will make adjusting parallax easier, or if it's not adjustable, will minimize its effects because it makes centering the eye more noticeable in the image.
 
Gordon said:
Repeatable proper cheek weld is an important technique that will help immensely.
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Bingo. As other posts noted above, if your eyesight is always perfectly centered (is the reticle centered in the field of view?) then fixed parallax isn't a problem. And it's cheek weld that determines where your eyeball is wrt to the scope's lense. This becomes a problem (at least for me) for differences in shooting posture between standing offhand and seated at bench w/ supported rifle.
 
Based on your title, I thought in a whole different direction. Then that's where my experience with parallax lies.

With air-guns and .22 rimfires shooting under 100 yards is another application for parallax adjustment. The difference between 10yds and 100 is a whole power of 10 and when stalking those wily, black stripped, brown rats it's almost required.
 
I have found that scopes with a fixed parallax at 100 yards don't work all that well for the shorter ranges normally encountered with rimfire and air rifles. I have also had issues with the same scopes when pushed to farther distances of 600 yards or more. It very well could be my eye sight too. I always buy scopes with adjustable parallax. I have an older Bushnell Elite 6-24 MIL-DOT with an adjustable objective and the rest of my scopes are side focus. I definitely prefer the side focus scopes.
 
gunsrfun1 said:
...I am thinking of buying a Burris E1 Fullfield 4.5-14, for the extra bit of magnification and the more precise reticle.
Click to expand...
My strong recommendation is to get the adjustable focus because it offers a functional benefit, especially when shooting targets. You will like being able to see the target as clearly as possible and are unlikely to want to return back to a non-adjustable scope for anything other than hunting large animals or target shooting at distances that match the fixed parallax setting.

Also, the Burris Fullfield II and Fullfield E1 in 4.5-14x42 are great scopes. I have three of each, have compared them carefully against a bunch of more costly Leupold, Sightron, Weaver, Vortex, and Clearidge scopes, and the Fullfields are simply very good (none of the others are really better, IMO). They were great when they sold for $300, but now that you can (temporarily?) buy them for about $150, they are a huge bargain. Side Focus is the way to go, IME, for convenience/ergonomics, so I'd get the E1. Having compared both of the Fullfields using an optical resolution target, I can't tell any meaningful difference between the optical quality of the two.
 
Thanks l6turbo, I am leaning toward the E1 at this point. I have an E1 in 2-7x35 and really like it.
 
gunsrfun1 said:
Got it, thanks all of you. So basically, with a scope with fixed parallax of 100 yards, the further away I get from 100 yards, the worse things will get (potentially) as far as POA/POI. I've got a couple "100-yard parallax" scopes that seem to serve me well up to 200 yards (one on my AR as mentioned above, and one on a hunting rifle). Both are "minute of gong" at 200 yards. But I have never gone further than that with either rifle. As jmr notes, I do try to look through the center of the scope, so that helps
However, since I want this new rifle to be a "precision" rifle to some extent, it sounds like I should mount a scope with adjustable parallax, just for some extra assurance.
Let me know if I have missed anything.
Thanks again.
Click to expand...
i do believe that most factory scopes are parallax free at 150 yards. that may be why your 200 yard shots are not affected. parallax adjustment on a scope is always nice to have.

luck,

murf
 
I can say, parallax isn’t just prevalent when you are shooting farther than the internal setting, but also when shooting shorter.

I can notice, significantly, a hindrance in creating my reticle picture when shooting 15-25 yards even with an adjustable parallax rifle which only comes down to 50yrds. I bought a set of NRL22 targets for my home range and shoot some of the monthly matches for practice, and hitting that little 3/8” TYL swinger even at 25 yards is a bear - especially when you can’t bring the reticle in focus with the target concurrently because the parallax focus will not adjust low enough.
 
It’s necessary on a high quality rimfire rifle because I’ve been told so many times on the Internet. That’s why I have an AO scope on my CZ 512 .22WMR. In reality I set it at 50 yards the first time I shot it and not once have I ever changed it.

I believe the Fullfield to be a MUCH better scope than a Crossfire.
 
Varminterror said:
I can say, parallax isn’t just prevalent when you are shooting farther than the internal setting, but also when shooting shorter.
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I agree, it certainly helps my old eyes.

I still haven't convinced one of our guys at work it isn't a focus knob though, and I partly blame the scope makers who are calling parallax knobs a focus knob. I tried unsuccessfully to explain to him how to adjust his scope to his eye. He listened to me when I suggested a good scope at a good price, I guess he figured if I was getting one it was a good buy, and he needed one to put on his new 6.5 Creed for hunting a couple years ago. He loves it, says it's clear, and does great at dusk, but I can't convince him the parallax knob isn't a focus knob. But he might have gotten lucky, and the eyepiece is focused for him, who knows.
 
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Varminterror said:
I can say, parallax isn’t just prevalent when you are shooting farther than the internal setting, but also when shooting shorter.

I can notice, significantly, a hindrance in creating my reticle picture when shooting 15-25 yards even with an adjustable parallax rifle which only comes down to 50yrds. I bought a set of NRL22 targets for my home range and shoot some of the monthly matches for practice, and hitting that little 3/8” TYL swinger even at 25 yards is a bear - especially when you can’t bring the reticle in focus with the target concurrently because the parallax focus will not adjust low enough.
Click to expand...

I have to agree. It is nice having a scope that you can adjust the parallax down to 10 or 15 yards when using it on a rimfire rifle or air rifle. I have had issues with some scope that only adjust down to 50 yards when shooting at targets closer than that.
 
For many years my primary rimfire hunting rifle wore the only A/O scope I owned. As much as I loved it at the range I hated the thing in the woods as was well rid of it. Until...I realized recently that I had never been overly clever about pre-setting the parallax for woods carry.

More often than not I took to the squirrel woods set at 50 or 100 yards parallax free but putting critters in the crosshairs at 20 yards. I found that a hindrance, having to fiddle with the ring with animal watching.

Fast forward and I’m finding more and more value in adjustable parallax including nearly all of my hunting rifles going forward. Those i shoot purely for fun at the range now sport A/O and field rifles are fitted with side adjustment.

Knowing your environment ahead of time is key and no time is lost if distance is judged previously. That proved out Saturday when I reminded myself to return my setting from 200 yards back to 100 where most of my shooting is done afield. 94 yards unsupported and a DRT buck.
 
Number of years ago I had a nice custom-built XP-100 pistol that i put a 3-12X Burris LER scope on. Started to develop loads with it and i couldn't get it to group at all. Frustrated as hell I sat there at the bench thinking it over. So I finally checked parallax and it was as big as the group. When I adjusted the parallax out the next group was TIGHT. Packed it up and went loading/hunting. Have seen this sort of error more than once with parallax.
 
Back four or five lifetimes ago in my high school days (60’s), I had a .22-250 with a fixed 10x. The parallax was very noticeable. If I didn’t take care to center my eye, I could be clear off a groundhog at 300 yards
 
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