Mathematically, the maximum error in parallax you could cause with a 40mm scope that is fixed for 150 yards, when shooting at 500 yards is 0.36 MOA or 1.8".
Fixed parallax for the range, bad choice?
- Thread starter gyppo
- Start date
Mathematically, the maximum error in parallax you could cause with a 40mm scope that is fixed for 150 yards, when shooting at 500 yards is 0.36 MOA or 1.8".
Awesome scope you got there.
Just use the parallax dial to make the target as clear as possible then both parallax and focus are set.
To try it. Take your .222 and aim at something small at 25 yards with 16X zoom and you will see a noticeable difference when you dial the parallax up and down. When at the 25y setting the target will be clear and and at 100yd it will slightly out of focus but probably still very useable.
Cheers
I lay my rifle on the bags (or bipod) and shift my head left and right to see the reticle move on the target. I then adjust the parallax until that no longer occurs. For me at least, that seems superior to judging solely based on focus, which tends to have a wider acceptable range.
Thanks. I didn't actually calculate anything just used 1MOA as it was easy. How did you calculate your numbers? Doesn't also the length of the scope and the distance of one's eye is to the ocular lens come into play? I would think so
Would be cool to figure that out.
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- Location
- Western Manitoba
I am sort of like this - I think "parallax error" and "target focus" are two different things, caused by different (related) systems within the scope - I think some scope manufacturers would want you to believe they are the same thing. When I want to check for parallax error, I do as above. And then separately fuss about the target focus - I do not think they are one and the same thing - but some modern scopes might make it appear to be so - whatever works for the shooter, is what counts. That shooter's explanation for his success, might not be correct, though.
Unfortunately I have nowhere to shoot further than 200 yards so I don't have much concern about parallax. I always make sure to position myself behind the rifle to obtain a natural point of aim. Mostly I use the sidefocus with my .22s at 25yrds or my main centerfire rifle at 100 when I want the clearest image possible for load development testing.
- Location
- Western Manitoba
There was a thing at one time to install 1" centre fire scopes onto .22 rifles - their parallax settings often were 150 yard - usually, though, they had MUCH brighter and maybe clearer images than you would see through the small diameter 22 scopes of the day. However, after installing a few - that parallax error was very evident on 20 or 25 yard targets, if you checked for it - even though the "customer" did not appear to know anything about it - his claim was usually how well the thing worked, compared to what he was using before.
It is possible that those dudes had really consistent "cheek weld" on their rifles - hence any parallax sighting error would be the same every time - and as a result, their bullets would always be going to where they wanted them to.
A few summers ago, I had a "new", directly out of the box, Leupold fixed four power rimfire scope - the pamphlet said the "parallax" was set for 60 yards. On sandbags in my shop, looking through it at a knot in a nearby tree through the garage doors - the knot was perhaps the size of a golf ball - about size of a squirrel's head, I thought - the knot was perhaps 15 yards from the scope - by moving one side to start to see black, then going other way to see black, I could move those cross hairs completely off that knot - either way. That is my understanding what parallax sighting error is about - where your cross hairs align on the target, is a function of where your eye is behind that scope, if you are not at precisely that "parallax free" distance. If your target is big enough, or if you look through the scope consistantly enough - then that error probably won't matter to you.
It is possible that those dudes had really consistent "cheek weld" on their rifles - hence any parallax sighting error would be the same every time - and as a result, their bullets would always be going to where they wanted them to.
A few summers ago, I had a "new", directly out of the box, Leupold fixed four power rimfire scope - the pamphlet said the "parallax" was set for 60 yards. On sandbags in my shop, looking through it at a knot in a nearby tree through the garage doors - the knot was perhaps the size of a golf ball - about size of a squirrel's head, I thought - the knot was perhaps 15 yards from the scope - by moving one side to start to see black, then going other way to see black, I could move those cross hairs completely off that knot - either way. That is my understanding what parallax sighting error is about - where your cross hairs align on the target, is a function of where your eye is behind that scope, if you are not at precisely that "parallax free" distance. If your target is big enough, or if you look through the scope consistantly enough - then that error probably won't matter to you.
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Resetting the parallax for rimfire distances is actually quite easy on most fixed power scopes.
At the objective end if you look closely there is usually a fine line a small distance from the end. On a Leupold its everything in front of the gold ring (which is just a spacer.) This is more or less a thread protecting cap that the objective lens carrier hides behind. Getting it off is the hardest part, but if you can get a grip on it hand pressure is usually enough. Once that's off you'll see a threaded tube with 2 or 4 slots on the end. Turn that out to shorten the distance that the scope is parallax free at; or in the lengthen the distance. It doesn't take much; a 1/4 turn is a big adjustment. Replace cap and you're done.
Now that is some interesting INFO . Thanks for that . RJ
Yeah; I’ve had to use a strap wrench too at times. Another trick is to wrap it with masking tape then twist a length of tape til its like a loose sticky rope, then wrap that. All kinds of grip then; whether by hand or a nylon strap wrench. If you need a little extra help adjusting the carrier a hacksaw blade makes a decent tool; just lay it back first across the slots. Usually it’ll come by hand though.
All this should be used with a “first do no harm” mentality. If things don’t come with a reasonable force it might be a good idea to quit and forget about it.
Some random thoughts: its one thing to use the technique to repurpose a scope to rimfires, muzzleloaders or short range arms. It is useful for finding a better compromise across the range of distances it’ll be used at. On the other hand, if your scope has always been good and then went sour it might be a good idea to view it as a symptom of something coming apart inside. Those pieces never turned themselves. A bit like adjusting carb idle screws; small changes to optimize things are fine; large changes just to get it to idle are a sure sign of other issues. Those screws don’t turn themselves either.
Thanks for all the replies everyone. There is a LOT of excellent info here. I'm not a bench shooter, I shoot off hand standing for the most part so it's great to read more about it.
I've read through the whole thread a couple of times, there is a lot to work on. But a repeatable cheek weld, a more consistent rest (bipod?) and maybe a rear bag, and some focus on breathing and trigger control is what I'm taking away here. We'll also try to dial the magnification down to 8-10 next time out.
As I said I'm not much of a marksman so it's hard to tell how much is the rifle/scope combo and how much is the shooter. Next time out I'll bring out some hand loads and see if there's any improvement with any of them. I'm trying Hornady 55 grain SPs with H335, I also got some CFE223 to try out.
To be continued.
I've read through the whole thread a couple of times, there is a lot to work on. But a repeatable cheek weld, a more consistent rest (bipod?) and maybe a rear bag, and some focus on breathing and trigger control is what I'm taking away here. We'll also try to dial the magnification down to 8-10 next time out.
As I said I'm not much of a marksman so it's hard to tell how much is the rifle/scope combo and how much is the shooter. Next time out I'll bring out some hand loads and see if there's any improvement with any of them. I'm trying Hornady 55 grain SPs with H335, I also got some CFE223 to try out.
To be continued.
- Location
- Blaster land, Okanagan BC
Fundamentals of marksmanship are the key most of the time, it crosses over regardless of what you are shooting. Stance, grip, sight picture, trigger press, follow through, we’re what I was taught in a beginner’s pistol class. Did it ever make a difference in my shooting, for rifles I’d add breathing in there before trigger press.
Whenever I start rushing or notice groups going to shít, it’s usually me not taking the time to make sure I’m consistently repeating my fundamentals and doing my part. That is if my rifle/rings/scope is set up correctly and I’m using ammo the rifle shoots well, I’m the weak link usually.
I remember taking a friend to the range to sight something in, he was fairly new to shooting so I ran him through the fundamentals and he was able to shoot some decent groups and get sighted in. Halfway through the day I was watching him blast away and notice groups open up, he was rushing and not taking the time to follow through and re align his sights before allowing the trigger to reset. Groups went back to normal once he did his part, after awhile the fundamentals become second nature but you need to spend the time to beat them into your brain.
Once I’m out in the bush hunting or shooting it’s second nature as I’ve spent my range time doing the fundamentals, I don’t have any issues with the fixed parallax scopes I hunt with because I have a solid repeatable cheek weld and grip. I just don’t have to think about it, it just is.
