Quick Drop vs Danger Space

[RockAndSage]

5k ft DA changes can easily happen in a day, but you're right, it's not a make or break. Just another couple tenths of error. If you were already dealing with some error, it could put bump you out of the vitals. So maybe correcting within a day is a little over dramatic. But I personally have hunted 10k+ DA variations from one week to the next, so you might still be adjusting week to week.

DA and the ballistics calculations of all of this in precision rifle are still pretty foreign to me, I genuinely didn't/don't know how much it would need to be accounted for at 600yds and in, what causes changes in DA, etc.

 

[Kjc103]

I do practice quick drop. Question I have is why a bdc turret (ie one marked in yardage, not in angular measurements) is any more problematic than quick drop itself.

To me basic quick drop without a “correction factor” is simple and easy and makes perfect sense to me. What Im missing a bit is why a bdc turret is problematic in comparison, because all of the factors that add variability to a bdc turret, also add exactly the same variation to quick drop. So if you are willing to accept that quick drop is “close enough out to xx range”, why is a bdc turret any different? Is it simply that it prevents or makes it more difficult to utilize a correction factor? Or?

In either case a cartridge with more “danger space” will be more forgiving of any method that involves “close enough”. Seems a cartridge on the high-end of fitting into quick drop would be quantifiably better than a cartridge on the low end of fitting. At a minimum, from that perspective danger space seems relevant and beneficial to quick drop, at least to a point.

It’s pretty tough to argue with your logic here.

 

[Kjc103]

Another thing folks aren't discussing here is that cartridges with more danger space than a "good" QD gun would give are going to be high recoiling and/or have very limited barrel life and/or very restrictive barrel heating.

Any really fast 7 or 6.5 with high BC bullets kicks way too much for 98% of shooters to shoot well over and over again. Muzzle brakes mitigate this only on the surface, and make other aspects of shooting and communicating much harder (vs suppressors, which typically mean lower recoil cartridges).

A 6UM burns a barrel in under 1k rds, which I don't care about from a cost perspective, but from a simple reliability/usability perspective. You might be on shot 600 shooting fine and see the gun absolutely shit itself and throw grape shot groups by round 650. Next barrel might be good to 750 but you aren't sure and don't want to have it go out during a hunt, so you pull it at 600 just to be safe. At those round counts I would be doing a barrel every year or maybe every other year, which is simply too much hassle for me to tolerate. Or, I leave it alone and don't shoot it much - which to me is also unacceptable. I want to practice consistently with all my guns, since they are all different and require different input to shoot correctly.

22CM or some other fast 22 might literally be the only cartridge too good for QD that maximizes danger space and doesn't have any other horrendous drawbacks. Though barrel life is right on the line.

Good point.

I’m actually shooting mostly 308 right now simply for simplicity (QD) and barrel life.

 

[nm.otter]

DA and the ballistics calculations of all of this in precision rifle are still pretty foreign to me, I genuinely didn't/don't know how much it would need to be accounted for at 600yds and in, what causes changes in DA, etc.

Try some potential pressure altitude, temp and humidity scenarios in your ballistics app and see what happens to your charts.

 

[Macintosh]

Try some potential pressure altitude, temp and humidity scenarios in your ballistics app and see what happens to your charts.

The 270win Ive been using as my example has a .2mil change in dope at 600 yards between 0’ DA and 6000’ DA. Now, if we’re saying .1 or .2mil off from actual dope is acceptable as part of QD, then .2 isnt a lot. BUT it’s on top of any other error including QD’s +\- inherent “close enough” error, ranging errors, environmental, precision of gun, wobble, etc. FWIW my 6.5cm in the exact same situation has a .3mil change.

At the same time I think virtually no one goes up or down 6000’ in one hunt, that takes some serious elevation or a roughly 100-degree temp swing. It begs the question of how much change in DA is truly relevant vs just needlessly overcomplicating things; but also being cognizant that the error is additive and if you had .1 or .2 mil fudge-factor before, it may no longer be “ok” if that grows to .3 or .4+ without taking it into account. Also obviously if we’re accepting .1 or .2 mil error that is +\- meaningless at 300 yards, but probably meaningful at some longer range.

For you folks who use and have a lot of field experience with quick drop, where are your parameters as far as what is max “quick drop” range for a 1st shot at an animal (ie not for a follow up on an already-wounded animal), and how much change in dope does it take to cause you to make corrections to your qd math for environmentals?

It strikes me that a gun with higher “danger space” might be a tough fit for QD in the first place, but might be more forgiving of the max range where qd can legitimately be used, and of changes to your QD math. Those things alone seem valuable, maybe?

 

[solarshooter]

At the same time I think virtually no one goes up or down 6000’ in one hunt, that takes some serious elevation or a roughly 100-degree temp swing. It begs the question of how much change in DA is truly relevant vs just needlessly overcomplicating things; but also being cognizant that the error is additive and if you had .1 or .2 mil fudge-factor before, it may no longer be “ok” if that grows to .3 or .4+ without taking it into account.

Just as an example, say you wake up at 2000ft and 30deg (500ft DA). Then you climb another 2000ft throughout the day, and it warms up to 70deg (5500ft DA). That's a 5000ft DA change in one day, and an extremely common scenario (for me at least, where I hunt in the weather I can get during hunting season).

For you folks who use and have a lot of field experience with quick drop, where are your parameters as far as what is max “quick drop” range for a 1st shot at an animal (ie not for a follow up on an already-wounded animal), and how much change in dope does it take to cause you to make corrections to your qd math for environmentals?

However, that's only a 0.1-0.2mil error vs standard QD even out to 600+ yds. I would generally look at where I'm hunting and the predicted weather and check a range of conditions in my ballistics app to figure out if I need to incorporate or modify a correction factor. Both of my main guns are very close to perfect QD guns with no correction factor, and so I don't need to react unless it's a BIG change. But last year, I went from 7000ft mean altitude and 60-70deg down to sea level and 45deg from one weekend to the next, and that required an adjustment. Which again is just a mental correction factor.

My guns are such good QD matches that I can shoot to 700+ with negligible error using QD. However, due to the drastic and nonlinear reduction in hit rates on vitals sized targets beyond 500yds for most hunting scenarios, I work hard to avoid shots beyond 500yds. And QD is more than adequate to that range for me. So I do not consider it a limitation at all.

Here's a plot showing how my 284 shooting a Berger 175 EH at 2670fps tracks QD:

This is with no correction factor. Within about 3" outright. Within 2" from ~300 to 800+yds. The jog in the curve from ~150 to ~250yds is because I just override and hold 0.5mil in this range. This amount of error is trivial compared to the other sources of error in the shot, and therefore you will barely be able to even detect this in practice. And to be clear I am talking about shots under pressure on game sized vitals from imperfect positions in novel terrain and wind.

 

[RockAndSage]

Try some potential pressure altitude, temp and humidity scenarios in your ballistics app and see what happens to your charts.

I will. What app would you recommend?

 

[nm.otter]

Any of them will work -- AB, Shooter, GeoBallistics, 4DOF, etc.

 

[B_Reynolds_AK]

I will. What app would you recommend?

The Revic app is great and what I use now, as it’s needed for my BR4 RF anyhow.

 

[24valve]

The 270win Ive been using as my example has a .2mil change in dope at 600 yards between 0’ DA and 6000’ DA. Now, if we’re saying .1 or .2mil off from actual dope is acceptable as part of QD, then .2 isnt a lot. BUT it’s on top of any other error including QD’s +\- inherent “close enough” error, ranging errors, environmental, precision of gun, wobble, etc. FWIW my 6.5cm in the exact same situation has a .3mil change.

At the same time I think virtually no one goes up or down 6000’ in one hunt, that takes some serious elevation or a roughly 100-degree temp swing. It begs the question of how much change in DA is truly relevant vs just needlessly overcomplicating things; but also being cognizant that the error is additive and if you had .1 or .2 mil fudge-factor before, it may no longer be “ok” if that grows to .3 or .4+ without taking it into account. Also obviously if we’re accepting .1 or .2 mil error that is +\- meaningless at 300 yards, but probably meaningful at some longer range.

It does take a significant amount of DA change to have a noticeable effect within 600 yards, but it is possible as @solarshooter explained. You are correct in that compounding environmental error with potentially imperfect QD error does have the possibility to become unacceptable. I don't have any hard rule-of-thumb on how much DA is relevant, and address on a case-by-case basis.

Here is the way I handle it when I am hunting. Each morning, I'll check and set DA in shooter, then verify my quick drop. For this example, I'll start at 2,000' DA, and would use base +0.1 for QD. Note this is within 0.1 mil to 550.



DA is very easy to check with a chart or kestrel, so I do if there's a significant change in elevation and/or temperature since I set it that morning. I'll then input the new DA into shooter, and run it to compare the drop chart to what I am using for QD. To continue with my example, I gain elevation and it warms up so I check DA to be 5,000', and update shooter accordingly.



If it's different than before, I just mentally note a new QD. In this case, my QD remains base +0.1, but is now within 0.1 mil out to 600 yards.

To take it a step farther, let's say the DA is now 8,000'.



At this point, I would adjust my mental QD of the gun to be base with no modification. This will be within 0.1 mil of my calculated drop out to 675 yards.

This is lengthy to write up, but relative quick to perform once you understand when to check and what you are checking. Usually the morning of I set DA for the average elevation and temp I expect for the day and do not have to change QD for my gun.

For you folks who use and have a lot of field experience with quick drop, where are your parameters as far as what is max “quick drop” range for a 1st shot at an animal (ie not for a follow up on an already-wounded animal), and how much change in dope does it take to cause you to make corrections to your qd math for environmentals?

I usually just see at what point QD diverges too far from the calculated values, I prefer within 0.1 mil past 500 yards. You'll notice in my above example, when establishing QD for the given environmentals I will note "base out to 675". This is how far out it is close enough to QD and the maximum range that you're referring to.

Please note that rest of the situation factors in far more than QD max range when determining max shot distance for a given situation. The only way this factors in is if an animal is on the edge of max QD and there's a possibility of it moving past max QD and ballistics must be looked up or calculated.

It strikes me that a gun with higher “danger space” might be a tough fit for QD in the first place, but might be more forgiving of the max range where qd can legitimately be used, and of changes to your QD math. Those things alone seem valuable, maybe?

They would be more forgiving of max QD range and changes to QD if they didn't have the inherent problem of not matching up to QD in the first place, and unfortunately they only match up less with more distance.

 

[24valve]

I will. What app would you recommend?

+1 for Shooter. It's easy and simple to use, there's no weirdness with certain bullets like on some other apps, and uses DA.

 

[43.6N]

I will. What app would you recommend?

If Strelok Pro ever becomes available again, I really liked using that one.

Between Shooter App, and Applied Ballistics, I think Shooter is more straightforward, and probably the best once you learn how to navigate. It hasn’t steered me wrong as long as I remember to update DA.

Applied ballistics has a ton of features that I think go a little beyond the type of shooting that we typically do as hunters. Their custom bc profiles have some issues. The WEZ is a nice visualization of statistical probability. 100% a Bryan Litz thing.

The key is just being able to make range tables with drop, correction, wind, and velocity.

I haven’t found a good app besides Strelok that will compute for the transonic and subsonic ranges very well. But that is so far into the weeds, I hesitate to even bring it up.

The Revic app is nice, but unless using one of their rangefinders, probably wouldn’t be my first choice. Their custom profiles have lined up well with my real life dope.

Hornady 4DOF is pretty buggy, and not worth using given the current options available.

I think that’s all the major players out currently.