Quick Drop vs Danger Space

[solarshooter]

to add to this, dispersion hasn't been mentioned yet as a source of error if compounded.
a 1.44" solid zero group is .4 Mil cone of fire, or 1.08" = .3 Mil.
Extrapolate that out to range and start adding fudged corrections, variables and other errors.

I would say that it's precisely BECAUSE of all the other dispersions/errors present that QD works well in hunting scenarios on hunting sized targets. All that other noise means the loss in precision from QD has a much smaller or harder to detect effect on the overall achieved precision. Range error, wind error, position error, aiming error, environmental error, stress error, we suck error, all combine to turn your 0.4mil benchrest system into a 0.8-1mil plus system in hunting scenarios under pressure. Another 0.1-0.3mil variable dispersed in there doesn't materially change the overall cone of fire.

That's also why QD does not work as well or is not as recommended for precision/competition shooting on smaller targets. You would notice the error much more/it would make more of a material difference in hit rate.

 

[Chris in TN]

Look at the cold bore challenge hit rates.

My premises are these:
Shooters suck
Danger space calculates the size of permissible error on the shot that will still result in a kill.
At 400, 2 moa field efficiency means roughly an 8” group.
At 500, 2 moa is 10”.
Past 400 the danger space shrinks quick enough that available range of error diminishes quickly.
Quick drop adds uncertainty to the equation.
Using good dope reduces calculation errors.

Conclusion:
When it comes to quickly shooting, MPBZ is the go to method for realistic shots you can make quickly.

Get a flat shooting cartridge for longer MPBZ and for larger “danger space”.

Use a ballistic calculator, it can be done as fast as ranging plus waiting a half second for the dope.

.....and to top that off, mark yardages (or meters if that's how you do it) on your elevation turret.

 

[longrangelead]

I would say that it's precisely BECAUSE of all the other dispersions/errors present that QD works well in hunting scenarios on hunting sized targets. All that other noise means the loss in precision from QD has a much smaller or harder to detect effect on the overall achieved precision. Range error, wind error, position error, aiming error, environmental error, stress error, we suck error, all combine to turn your 0.4mil benchrest system into a 0.8-1mil plus system in hunting scenarios under pressure. Another 0.1-0.3mil variable dispersed in there doesn't materially change the overall cone of fire.

That's also why QD does not work as well or is not as recommended for precision/competition shooting on smaller targets. You would notice the error much more/it would make more of a material difference in hit rate.

at range QD is most often applied by those that know their limit, I'd agree.
I just wanted to point it out as the error we all start from, that and we suck under pressure.
We tend to obsess over the minutia of data, scope tracking, etc, but the hard errors like base accuracy and skill don't get talked about as much, more lately, but the other sources get mentioned far more it seems.

 

[Macintosh]

Well, yeah, thats precisely why I mentioned it, and its also in part why I asked how far people were stretching QD. I know few of us can say our dope is PERFECT, I cant. Nor is my gun perfect given I havent met one yet that one-holes every shot. Any error we introduce by virtue of using a “close enough” shortcut is going to be adding to our imprecision. And my own error is on top of all that. Personally, I count on all of these errors being cumulative. That is certainly the worst case, but you can rely on that happening some portion of the time.

 

[Chris in TN]

Well, yeah, thats precisely why I mentioned it, and its also in part why I asked how far people were stretching QD. I know few of us can say our dope is PERFECT, I cant. Nor is my gun perfect given I havent met one yet that one-holes every shot. Any error we introduce by virtue of using a “close enough” shortcut is going to be adding to our imprecision. And my own error is on top of all that. Personally, I count on all of these errors being cumulative. That is certainly the worst case, but you can rely on that happening some portion of the time.

The cumulative error of using QD or a yardage marked turret at some middle level of DA on most hunts wil be maybe +/- one scope click at 600 yards.

That’s probably not a problem at 500 with a steady position. It’s a caution light at 600 - slow down and consider whether your immediate DA and shot angle call for dialing short or long. I see it as being ‘red’ at 600+. Stop and fully assess the shot and work the math or don’t take it.

And I say that as someone who doesn’t want to shoot game past 400-500 anyway.

 

[Macintosh]

Zero it at 145 yards and do that math.

You’ll have useable solution out to 700 yards without remembering any little adjustments.

Assumption:
2.1 bore height
6300 DA

Follow up on this.

My 20” 6.5cm which has more drop than basic qd formula allows, becomes pretty close to spot-on with a 140 yd zero. My sight height and DA are quite different than yours, but it still works, and it works across a wide range of DA.

My 270/lrx combo, no amount of fiddling with zero distance helps. On an extremely cold morning at sea level (ie DA of +\- -4000’) its ok, but as soon as I go up in DA to normal shooting/hunting it goes south fast. Zero distance does not seem to help this gun.

Regarding the give and take between qd and danger space (remember that?) it seems manipulating the zero distance is more of a trick for guns that are slower than is “qd ideal”, not so much for a flatter shooting gun. So this does not seem to be a trick that would allow having your QD cake, and eating it too (high danger space).

 

[Macintosh]

The cumulative error of using QD or a yardage marked turret at some middle level of DA on most hunts wil be maybe +/- one scope click at 600 yards.

That’s probably not a problem at 500 with a steady position. It’s a caution light at 600 - slow down and consider whether your immediate DA and shot angle call for dialing short or long. I see it as being ‘red’ at 600+. Stop and fully assess the shot and work the math or don’t take it.

And I say that as someone who doesn’t want to shoot game past 400-500 anyway.

Im not sure I agree on all counts.

The error from QD alone, if it lines up well, is .1 or .2mil. .2mil at 600yds is a little over 4”. That’s already completely off an 8” plate. Even if you give yourself a 10” or whatever size target, that leaves very little “budget” for much further error as the range approaches and exceeds 500, and you know for certain you can expect other error. It only takes .3mils of TOTAL error for a shot to be completely off of a 10” plate at 500 yards.

Given its never going to be the only source of error, Im curious what others think is an acceptable amount of error on target for their QD?

 

[solarshooter]

Im not sure I agree on all counts.

The error from QD alone, if it lines up well, is .1 or .2mil. .2mil at 600yds is a little over 4”. That’s already completely off an 8” plate. Even if you give yourself a 10” or whatever size target, that leaves very little “budget” for much further error as the range approaches and exceeds 500, and you know for certain you can expect other error. It only takes .3mils of TOTAL error for a shot to be completely off of a 10” plate at 500 yards.

Given its never going to be the only source of error, Im curious what others think is an acceptable amount of error on target for their QD?

Your hit rate on an 8" plate at 600yds will already be abysmally low. You are thinking only about the laser beam shot to POA, but if you instead picture a large cloud of shots, with only 20-30% hitting that target, and move that cloud off-center by 0.2mil, you might then only have 15-20% hitting the target. But the affect is relatively small, 5-15% reduction in hit rate, to the point that you would need a lot of shots to even confidently see that difference.

 

[Chris in TN]

Im not sure I agree on all counts.

I'm not going to respond to your QD points. I was speaking very generally and will let others chime in there if they want. But within the realm of scopes with 1/4moa elevation clicks and shots inside of 600 yards with moderate DA variations (which is how/what I actually shoot), it's a non-issue. At 500 yards it's a coin toss as to whether DA will ever change your solution by a full click, and on steep angles, app data indicates (and I don't live anywhere that I can flesh this out like I'd like, but generally trust app solutions) that you can ignore the first 5 degrees then drop a click of elevation for every additional ~5 degrees, up to a point.

Again, if you want perfect solutions, that ain't it, but that'll cover an awfully wide range of scenarios.

(ETA: And yes that ~5 degree figure varies between calibers/loads of course, but you can easily work out a figure that works for your rifle/load inside of maybe 30 degrees or less)

 

[solarshooter]

Your hit rate on an 8" plate at 600yds will already be abysmally low. You are thinking only about the laser beam shot to POA, but if you instead picture a large cloud of shots, with only 20-30% hitting that target, and move that cloud off-center by 0.2mil, you might then only have 15-20% hitting the target. But the affect is relatively small, 5-15% reduction in hit rate, to the point that you would need a lot of shots to even confidently see that difference.

Gotta love WEZ, though I can't input an elevation adjustment or aiming error. But this illustrates my point:

 

[Macintosh]

Your hit rate on an 8" plate at 600yds will already be abysmally low. You are thinking only about the laser beam shot to POA, but if you instead picture a large cloud of shots, with only 20-30% hitting that target, and move that cloud off-center by 0.2mil, you might then only have 15-20% hitting the target. But the affect is relatively small, 5-15% reduction in hit rate, to the point that you would need a lot of shots to even confidently see that difference.

We’re saying the same thing. Im specifically saying you CANNOT think of it like a laser beam. I’ll leave quantifying that to you or others. No idea what your inputs are there, but the point remains that at some point your dispersion (ie including all other sources of error) is marginal already for making reliable hits, and at that point introducing another random tenth or two is going to matter. Fact is people ARE taking 600 yard shots with XX hit rate assuming good dope…and adding another .1 or .2 of error into the mix IS going to affect that. 15% is a big reduction imo. Hence my question about how much error from QD people think is acceptable.

 

[Formidilosus]

Follow up on this.

My 20” 6.5cm which has more drop than basic qd formula allows, becomes pretty close to spot-on with a 140 yd zero. My sight height and DA are quite different than yours, but it still works, and it works across a wide range of DA.

My 270/lrx combo, no amount of fiddling with zero distance helps. On an extremely cold morning at sea level (ie DA of +\- -4000’) its ok, but as soon as I go up in DA to normal shooting/hunting it goes south fast. Zero distance does not seem to help this gun.

Regarding the give and take between qd and danger space (remember that?) it seems manipulating the zero distance is more of a trick for guns that are slower than is “qd ideal”, not so much for a flatter shooting gun. So this does not seem to be a trick that would allow having your QD cake, and eating it too (high danger space).

Do not change your zero to make QD work- that is absolutely opposite of the point of it, and is right back to fug fug games.


The simple answer for you is- it doesn’t line up for your local and combinations: don’t use it for that location and combinations. It is about a perfect panacea everywhere. I am still completely baffled as to why you are fighting with this so much- it’s doesn’t work for your location and guns; no big deal. It will/may work for the guns if you travel somewhere else. There are combos it doesn’t work with- so what? Understand how to use it, use it when it does work, and use it to get quick hits, or quick second round hits with random guns that you don’t have data for.

 

[Macintosh]

Do not change your zero to make QD work- that is absolutely opposite of the point of it, and is right back to fug fug games.

Can you explain why in some detail? To be honest that makes no sense at all to me. I zero at 100 yards instead of 200 yards because I get a better zero, but it’s not SO different, and the difference between 100 and 140 is not the same as 100 and 200. Whether I’m zeroed at 100 or 140 yards seems irrelevant, the difference on target is inside the guns dispersion anywhere inside the zero distance, the data in my calculator is still the data in my calculator, and if it lines up perfectly with quick drop, then I have super easy second shots or on the fly adjustments. Even if it will need an adjustment if Im heading to 10,000’…other than having a 1cm @ 100 yard zero offset, if I’m not traveling between very different areas on a regular basis what is the actual down-side?

The simple answer for you is- it doesn’t line up for your local and combinations: don’t use it for that location and combinations. It is about a perfect panacea everywhere. I am still completely baffled as to why you are fighting with this so much- it’s doesn’t work for your location and guns; no big deal. It will/may work for the guns if you travel somewhere else. There are combos it doesn’t work with- so what? Understand how to use it, use it when it does work, and use it to get quick hits, or quick second round hits with random guns that you don’t have data for.

The reason I’m trying to understand better, is because based on you and others making such a big deal about it I’ve practiced with it relatively extensively for the past couple seasons, and where it lines up I found it to work quite well at moderate ranges. I LIKE it. Then I went and chopped my barrel for a suppressor, and here we are. So I want to continue practicing with it to become more proficient, but since my practice happens so far away from where Id most use it hunting, there is some requirement to have it work both at very low and very high DA. I’m trying to understand where the boundaries of it are and what my options are to work with that. Thats all. If I had unlimited range time Id figure it all out for myself. But I dont. And Ive intentionally whittled myself down to a couple rifles, so I dislike the idea of just adding a rifle for this without exhausting options. Seems perfectly legit to me, but Im genuinely sorry if its been a drag for folks or taken this off topic.

 

[Formidilosus]

Can you explain why in some detail? To be honest that makes no sense at all to me. I zero at 100 yards instead of 200 yards because I get a better zero, but it’s not SO different, and the difference between 100 and 140 is not the same as 100 and 200. Whether I’m zeroed at 100 or 140 yards seems irrelevant, the difference on target is inside the guns dispersion anywhere inside the zero distance, the data in my calculator is still the data in my calculator, and if it lines up perfectly with quick drop, then I have super easy second shots or on the fly adjustments. Even if it will need an adjustment if Im heading to 10,000’…other than having a 1cm @ 100 yard zero offset, if I’m not traveling between very different areas on a regular basis what is the actual down-side?

First- answer why a 100y/m zero is optimum. As soon as you answer that in full- you have all the answer your need.

But, second- if you make QD work by zeroing at 140 yards; then you can just add .1 mils to base QD and you have the same thing. It doesn’t change anything.

Zeroing one gun at “x” range, and another at “y” range, but another still “z” range- oh and one at “p” range……. It’s all a bunch of nonsense bafukery. Zero everything at 100y and go from there.

The reason I’m trying to understand better, is because based on you and others making such a big deal about

I haven’t made “such a big deal about it”. I don’t build rifles around matching it- that’s other people doing so…. Though I understand why they do.
“Quick drop” is about being able to make relatively easy calculations in your head without external sources. That’s why it is taught at the base level as “average gun”, “bad gun”, “good gun”. And then, corrections for specific rifles.

Quick drop is at its core- a skill, not a product or a thing. I use ballistic LRF binos, I use ballistic apps, I’m the one that showed people here to set your drop table for the day as the lock screen on your phone- etc, etc. Quick drop is a skill that is possible because of mils and because Jesus loves tens- it was never intended or taught as the way to correct for elevation.

it I’ve practiced with it relatively extensively for the past couple seasons, and where it lines up I found it to work quite well at moderate ranges. I LIKE it. Then I went and chopped my barrel for a suppressor, and here we are. So I want to continue practicing with it to become more proficient, but since my practice happens so far away from where Id most use it hunting, there is some requirement to have it work both at very low and very high DA. I’m trying to understand where the boundaries of it are and what my options are to work with that. Thats all. If I had unlimited range time Id figure it all out for myself. But I dont. And Ive intentionally whittled myself down to a couple rifles, so I dislike the idea of just adding a rifle for this without exhausting options.

You will have to change gun, change cartridge, or change bullets to do that. But n your 6.5cm load 130gr for where you are, and shoot 140 or 147gr out west. Otherwise, it’s a correction factor for QD.

Seems perfectly legit to me, but Im genuinely sorry if it’s been a drag for folks or taken this off topic.

Not at all- you’ve spoken to me. It just seems like you are trying to force a square peg in a round hole.

 

[RockAndSage]

First- answer why a 100y/m zero is optimum. As soon as you answer that in full- you have all the answer your need.

But, second- if you make QD work by zeroing at 140 yards; then you can just add .1 mils to base QD and you have the same thing. It doesn’t change anything.

Zeroing one gun at “x” range, and another at “y” range, but another still “z” range- oh and one at “p” range……. It’s all a bunch of nonsense bafukery. Zero everything at 100y and go from there.





I haven’t made “such a big deal about it”. I don’t build rifles around matching it- that’s other people doing so…. Though I understand why they do.
“Quick drop” is about being able to make relatively easy calculations in your head without external sources. That’s why it is taught at the base level as “average gun”, “bad gun”, “good gun”. And then, corrections for specific rifles.

Quick drop is at its core- a skill, not a product or a thing. I use ballistic LRF binos, I use ballistic apps, I’m the one that showed people here to set your drop table for the day as the lock screen on your phone- etc, etc. Quick drop is a skill that is possible because of mils and because Jesus loves tens- it was never intended or taught as the way to correct for elevation.






You will have to change gun, change cartridge, or change bullets to do that. But n your 6.5cm load 130gr for where you are, and shoot 140 or 147gr out west. Otherwise, it’s a correction factor for QD.





Not at all- you’ve spoken to me. It just seems like you are trying to force a square peg in a round hole.

All the detail and explanations are very helpful for me personally, from everyone, it's appreciated.

 

[24valve]

We’re saying the same thing. Im specifically saying you CANNOT think of it like a laser beam. I’ll leave quantifying that to you or others. No idea what your inputs are there, but the point remains that at some point your dispersion (ie including all other sources of error) is marginal already for making reliable hits, and at that point introducing another random tenth or two is going to matter. Fact is people ARE taking 600 yard shots with XX hit rate assuming good dope…and adding another .1 or .2 of error into the mix IS going to affect that. 15% is a big reduction imo. Hence my question about how much error from QD people think is acceptable.

I'll preface this response with the bigger picture of first round hit rates in complex terrain on an 8" circle at 600 yards are quite low as @solarshooter showed with WEZ to the point that a very small minority of even skilled, practiced, shooters should be shooting at game that far (myself excluded). So assuming someone is that skilled, we are taking QD to the extreme edge of it's capabilities, when it's most useful at medium ranges, say 2-450 yards.

Something else to keep in mind with the WEZ percentages is that while 15% seems like a lot, put it in the frame of reference of you shooting one shot in 100 different situations where the target size and distance happen to be the same. That is very different than shooting the same situation 100 times, and 10% is probably the start of possibly seeing a tangible difference in real hit rates in the field.

With that being said, I believe the point he was trying to make was that .1/.2 mil error is mostly swallowed in all the other error. To demonstrate that, I accounted for that .1/.2 by adjusting the range error in WEZ (which is 2SD, so it goes both ways). The drop chart below shows that a 5 yard error on WEZ (the default for normal ranging error regardless of QD) will reflect dialing 4.0 to 4.1 (-0.1 mil difference), and a 10 yard error on WEZ will reflect dialing 3.9 to 4.2 (-0.2/+0.1 mil difference).




A 0.1 mil difference is already built into the minimum realistic ranging error and is a non-issue even at this range.


A 0.2 mil difference results in a 5% lower probability, which is functionally unseeable in reality. The range/QD error is proportional to the rifles dispersion (1.5 MOA, which is quite good for field shooting), but wind is 5 times larger error than both in this analyses and subsequently the main reason for missing/source of error.

Let's look at a less extreme situation: 12 inch target at 400 yards, same inputs as before.


Once again, 0.1 mil error is lost in the normal ranging error and makes no difference.



And 0.2 mil difference results in a 6% less probability of hit - functionally unseeable in reality yet again. The error from range/QD at 0.2 mil is now greater than the error from rifle dispersion, but the error from wind is still three time greater, and subsequently still main reason for missing.

I’m trying to understand where the boundaries of it are and what my options are to work with that.

So to summarize all the math dork-nerd stuff, the 0.1/0.2 error in QD is not going to be the reason you miss. Provided your rifle's ballistics match it, the boundaries of quick drop are outside of the other boundaries of a given situation.

To use your boundary analogy, below is the order and (not necessarily proportional) magnitude of the boundaries that will determine whether you will hit or miss in a given situation (also assuming your rifle is correctly zeroed).

(-Shooter Skill-)
(---------Wind Call---------)
(---------------Quick Drop-----------------)

The reason I’m trying to understand better, is because based on you and others making such a big deal about it I’ve practiced with it relatively extensively for the past couple seasons, and where it lines up I found it to work quite well at moderate ranges. I LIKE it. Then I went and chopped my barrel for a suppressor, and here we are. So I want to continue practicing with it to become more proficient, but since my practice happens so far away from where Id most use it hunting, there is some requirement to have it work both at very low and very high DA. I’m trying to understand where the boundaries of it are and what my options are to work with that. Thats all. If I had unlimited range time Id figure it all out for myself. But I dont. And Ive intentionally whittled myself down to a couple rifles, so I dislike the idea of just adding a rifle for this without exhausting options.

I've bolded the key part above - it works great where it does, but it is not a one-size fits all solution. Your rifles are at opposing edges of QD which is likely why you're having trouble fitting them without significant correction, and your extreme changes in DA make it difficult to match closely at either end.

Im genuinely sorry if its been a drag for folks or taken this off topic.

No worries, this is what rokslide is for. I appreciate your genuine curiosity and desire to learn and understand.