Bullet Drop

[Rivenoak]

At what point is bullet drop enough (in terms of inches on target) to account for? I understand that there are multiple factors that effect bullet drop such as caliber, zero, grain weight, ECT... I'm talking real world hunting situation for big game. Obviously you want to hit exactly what you are aiming for every time and only take clean ethical shots. For example if you are going to be about 2.5 inches low at a given distance on an animal would you try and account for it or just aim center of vitals?

 

[mcb]

Many hunters calculate and sight in for a maximum point blank sight-in. Depending on the bullet (ie ballistic coefficient), muzzle velocity and sight height over bore you can calculate a sight-in range that will give you the maximum range where the bullet's deviation from the line of sight is always within a specified offset. This is usually set at 3-inches but can be larger or smaller depending on your needs.

There are online calculators that can do the math for you. One example:

http://www.shooterscalculator.com/point-blank-range.php

Within this calculated maximum point blank range you just point and shoot. Beyond this range you need to start compensating for bullet drop in some way.

 

[Random 8]

Depends on a few things. Size and species of game animal, angle of shot vector through the vitals, precision capability of shooter/rifle/ammunition/conditions (we'll call it "system" going forward).

Lets take a common example, Whitetail deer with a .270 win. Ample power for the game even with a tough shot angle. Lets say, you're shooting from a permenant blind with a solid rest, and capable of 1.5MOA precision with the system. Despite all the internet cloverleafs people post, I'd call this best case real world precision from a hunting rifle. I'd say your vitals on a level shot are 7" top to bottom. Thats 3.5" from center. Subtract 1.5" of precision from the system, and you get a 2" margin for elevation error at 100 yards. Now subtract 3" precision, and you have almost no margin at 200 yards, you need to cheat a little high or zero your rile accordingly to get back into the Goldilocks zone. At 300 or more, you'd better have a good dope card made up. If you start getting into lower powered rounds or lower impact velocities at extreme range, I would shrink the margin of error somewhat.

Now lets take a higher shot angle, say 15 degrees. I'm not going to do the trig, but I'm thinking conceptually that your vertical margin for error has increased slightly as you're intercepting a wider cross section of heart/lung area.

Now interpolate that to your specific cartridge, game, angle and precision of your system, and see what works for you.

 

[horsey300]

At what point is bullet drop enough (in terms of inches on target) to account for? I understand that there are multiple factors that effect bullet drop such as caliber, zero, grain weight, ECT... I'm talking real world hunting situation for big game. Obviously you want to hit exactly what you are aiming for every time and only take clean ethical shots. For example if you are going to be about 2.5 inches low at a given distance on an animal would you try and account for it or just aim center of vitals?

Between range finders, ballistic apps, bdc scopes and mildots, holdovers are easy enough that you can adjust aim quickly, for 2.5 inches (assuming a 1.5moa shooter) at 200 yards (assuming deer sized game) you have a 9" circle to hit, center is 4.5inches from bottom, a 2.5 drop puts you 2 from bottom of vital circle, NOW factor in that 1.5 Moa group (1.5×2=3) and you could EASILY land outside the vital zone by 1"........as the distance grows, so does the group, yes, you should adjust your aim to put the bullet in center (i.e. find correct holdover to raise poi 2.5 inches or even a little higher)
Eta the truest answer is answered with the question, while 2.5 inches is not much, how far away can YOU hit the pie plate without adjusting poa, EVERY time?

 

[Rivenoak]

Between range finders, ballistic apps, bdc scopes and mildots, holdovers are easy enough that you can adjust aim quickly, for 2.5 inches (assuming a 1.5moa shooter) at 200 yards (assuming deer sized game) you have a 9" circle to hit, center is 4.5inches from bottom, a 2.5 drop puts you 2 from bottom of vital circle, NOW factor in that 1.5 Moa group (1.5×2=3) and you could EASILY land outside the vital zone by 1"........as the distance grows, so does the group, yes, you should adjust your aim to put the bullet in center (i.e. find correct holdover to raise poi 2.5 inches or even a little higher)
Eta the truest answer is answered with the question, while 2.5 inches is not much, how far away can YOU hit the pie plate without adjusting poa, EVERY time?

That makes sense. For my purposes a 2.5 in drop is at 200 yards which is the absolute longest shot I would consider taking at this point given experience and landscape I'm hunting. According to Hornadys ballistic calculator and personal experience with this rifle, scope and round I stay under a 1 in drop/rise until about 175 yards. Most of it is under 0.5 in. Would you still attempt to account for a half inch at say 100 yards? At that point I'm wondering if shooting ability is more reliable than estimating a half inch on an actual deer?

 

[horsey300]

Depends on a few things. Size and species of game animal, angle of shot vector through the vitals, precision capability of shooter/rifle/ammunition/conditions (we'll call it "system" going forward).

Lets take a common example, Whitetail deer with a .270 win. Ample power for the game even with a tough shot angle. Lets say, you're shooting from a permenant blind with a solid rest, and capable of 1.5MOA precision with the system. Despite all the internet cloverleafs people post, I'd call this best case real world precision from a hunting rifle. I'd say your vitals on a level shot are 7" top to bottom. Thats 3.5" from center. Subtract 1.5" of precision from the system, and you get a 2" margin for elevation error at 100 yards. Now subtract 3" precision, and you have almost no margin at 200 yards, you need to cheat a little high or zero your rile accordingly to get back into the Goldilocks zone. At 300 or more, you'd better have a good dope card made up. If you start getting into lower powered rounds or lower impact velocities at extreme range, I would shrink the margin of error somewhat.

Now lets take a higher shot angle, say 15 degrees. I'm not going to do the trig, but I'm thinking conceptually that your vertical margin for error has increased slightly as you're intercepting a wider cross section of heart/lung area.

Now interpolate that to your specific cartridge, game, angle and precision of your system, and see what works for you.

With a 225 yard zero (my systems all run 225ish zeros for easily compensated holdovers) a .243 launching a 90 gr tgk (5000 ft elevation pretty average dry climate) at 3020 fps will show a rise of 1.65 inches at 200 yards with a 15 degree slope, on a zero degree field it's a 1.35 change, so not a lot of help to a 1.5 moa shooter not adjusting poa.

 

[horsey300]

That makes sense. For my purposes a 2.5 in drop is at 200 yards which is the absolute longest shot I would consider taking at this point given experience and landscape I'm hunting. According to Hornadys ballistic calculator and personal experience with this rifle, scope and round I stay under a 1 in drop/rise until about 175 yards. Most of it is under 0.5 in. Would you still attempt to account for a half inch at say 100 yards? At that point I'm wondering if shooting ability is more reliable than estimating a half inch on an actual deer?

Your shooting ability IS the biggest factor, if I shoot past 200 on game, I guarantee I'm prone on a pod (with my hand loads that puts me sub moa way past 500 yds) .5 drift at 100 yds is no big deal on a deer, but honestly for directed to your uses input we need the scope you're using (any holdover marks at all?) Bullet (preferably b.c. and weight) and mv. In GENERAL a zero at 175-225 will keep MOST hunting rounds in the vitals from 50 to 250 yds, hitting 2-3 inches high at 100 and 1.5 low at 250 where you should start worrying more about wind drift and group size to plan for the what ifs that commonly happen in the field. At 200 yds a 1.5 moa shooter is already soaking up .33 to .5 of the vital zone, 15 mph crosswind and you're sideways 3 more inches with the CENTER of the group. If you're planning 200 yds here, you should set your scope and practice accordingly. Any time I take out hunters on pronghorn or deer I ask what range they normally practice at, and have to date, pissed off several by not allowing them to shoot further than their current skill set dictates. 200 yds is not hard, not even for a mediocre farm kid with an iron sighted .30-30 but knowing where to hold every time you let one loose is the difference between ethics as just poking holes in random stuff.

 

[Varminterror]

For example if you are going to be about 2.5 inches low at a given distance on an animal would you try and account for it or just aim center of vitals?

Correcting 2.5” is nothing of consequence - hold or dial, and deliver. 2.5” drop with a 2700-3200fps bottleneck cartridge is a chip shot.

Bottom line - If a shooter doesn’t know their trajectory at a given range, they shouldn’t be shooting that range.

Three things come into play for me when determining my maximum effective range - the shorter of the two always is the limitation:

1) Field position precision
2) Gross trajectory at range
3) sufficient impact velocity upon delivery

Expounding upon these:

Field Position Precision - in general, I don’t like to take shots on game beyond which I can deliver a heart shot. This means I abstain if I can’t deliver a 5” group for a whitetail deer from my field position, unless the shots are thoroughly planned prior to the hunt. If I’m laying prone, that might mean 600-700 yards with a high velocity bottleneck centerfire. I typically won’t own a rifle which doesn’t shoot sub-MOA from the bench or prone. If I take a standing shot, supported on a shooting stick, that might only be 200yrds. But if I don’t KNOW my group size would fit entirely within the size of the heart, I don’t like taking the shot.

Gross trajectory at range - game animals move. LRF beams are big, and accurately pinging game in the field can be a challenge. Knowing the EXACT range of an animal at the time of the shot can be difficult. I typically consider any range in which my load is falling over an inch per yard to be almost unmanageable on game, a half inch per yard is a challenge. Any range where you get to a “click per yard” is an exceptional challenge. It’s simply too easy to have an error of 2-3yrds in measured range when you get way out there, so compounding a POA error of 2” at, say, 600yrds, with a measurement error of 3 yards, meaning an inch of error in trajectory correction, plus the fact we can’t hold perfectly or dial perfectly to match our trajectory (a click at 600yrds is an inch and a half for a MOA scope, 2.2” for an mead scope), it’s far too simple to miss a deer’s heart. Wind is pretty simple here - if wind estimation error of +/-2mph can push me off target, then the shot is too risky.

Impact velocity - pretty simple. I need sufficient velocity upon impact, whether for reliable bullet expansion, or for penetration, it has to hit hard enough on the business end.

So... two extremes in my world: I hunt often with a 45-70 and often with 243win/6 creed/6 Dasher. My 45-70 is a 1.5 minute rifle from my shooting sticks in the blind, and it’s only running 1795fps. Impact velocity is low no matter what, but the big Gov’t doesn’t need much speed to punch hard and deep. It’s dropping 1/2” per yard by 300, also delivering about 5.5-6” groups in the field, such 250-300 is my manageable limit for that rifle. Alternatively, my 6 creed is a 1/2moa rifle shooting prone in the field, which means I could run it to about 1,000yrds on a 5” heart just based on group size. However, my gross trajectory is such I’m dropping about 3/4” per yard at 1000, every click in my scope is 3.6”, my crosshair stadia covers just under an inch of target... The wind is the kicker here. 2mph at 1,000yrds should be about 12” of drift, far too much to risk, for me. My impact velocity is also down in the mid 1600’s, below the reliable expansion window for the bullets I typically use - without enough bullet to reliably kill without expansion. Velocity and wind influence dominate here. So I pull that one back to about 600-700 yards in manageable wind, where I’m only dropping about .1” per yard, each click is only 2.5”, my crosshairs only cover about 1/2”, and the wind error is only about 5” of play - and my impact velocity is still over 2,000fps. If I can’t get prone, however, I shoot about 1moa from a hedge post with that rifle, such I’m stuck at about 400yrds, so my field group size becomes the rule.

Every unique combination of shooter, rifle and load, environmental condition, and field position is a law unto itself. These variables stack differently together to develop the shooting solution.

 

[Rivenoak]

Your shooting ability IS the biggest factor, if I shoot past 200 on game, I guarantee I'm prone on a pod (with my hand loads that puts me sub moa way past 500 yds) .5 drift at 100 yds is no big deal on a deer, but honestly for directed to your uses input we need the scope you're using (any holdover marks at all?) Bullet (preferably b.c. and weight) and mv. In GENERAL a zero at 175-225 will keep MOST hunting rounds in the vitals from 50 to 250 yds, hitting 2-3 inches high at 100 and 1.5 low at 250 where you should start worrying more about wind drift and group size to plan for the what ifs that commonly happen in the field. At 200 yds a 1.5 moa shooter is already soaking up .33 to .5 of the vital zone, 15 mph crosswind and you're sideways 3 more inches with the CENTER of the group. If you're planning 200 yds here, you should set your scope and practice accordingly. Any time I take out hunters on pronghorn or deer I ask what range they normally practice at, and have to date, pissed off several by not allowing them to shoot further than their current skill set dictates. 200 yds is not hard, not even for a mediocre farm kid with an iron sighted .30-30 but knowing where to hold every time you let one loose is the difference between ethics as just poking holes in random stuff.

Shooting a Savage axis .308 with a Bushnell banner scope. No holdover indicators. Round is Winchester deer season xp 150 grain. Bc is .392. muzzle velocity 2820fps. Zeroed at 50 yards. Always shooting from seated position in a ladder stand with gunbar. According to the ballistic calculator I don't get to an inch drop until 175 yards. Don't plan on pushing past 150 yards but watched a doe through the scope yesterday morning at about 225 and did not consider it an ethical shot. Killed 3 with this setup in the past 2 years with longest shot being about 45-50 yards. Honestly prefer keeping it close bc it feels more like hunting and less like shooting.

 

[horsey300]

Shooting a Savage axis .308 with a Bushnell banner scope. No holdover indicators. Round is Winchester deer season xp 150 grain. Bc is .392. muzzle velocity 2820fps. Zeroed at 50 yards. Always shooting from seated position in a ladder stand with gunbar. According to the ballistic calculator I don't get to an inch drop until 175 yards. Don't plan on pushing past 150 yards but watched a doe through the scope yesterday morning at about 225 and did not consider it an ethical shot. Killed 3 with this setup in the past 2 years with longest shot being about 45-50 yards. Honestly prefer keeping it close bc it feels more like hunting and less like shooting.

Alright, well, you'll have to calculate your own angle for your height above target but with that combo (Idk if you're a 1 Moa or 4 moa shooter so you're on your own there) zero .5 high at 50, and that should put you 1.6 high at 100, 1.5 high at 150 and dead on at 200 no holdover required for deer.

 

[Varminterror]

Don't plan on pushing past 150 yards but watched a doe through the scope yesterday morning at about 225 and did not consider it an ethical shot.

If it’s not ethical for you with your current state of experience, then it’s good you held off.

In proper hands, given that load and rifle delivering no more than 1.5moa from seated with a gun bar, that round and bullet would easily have dropped that doe at twice that distance.

 

[Rivenoak]

I appreciate the information and I'm not trying to oversell my ability shooting but I feel with some practice and changing my zero for a longer distance I could achieve a 200 yard shot way more easily. I realize the rifle is extremely accurate and has plenty of knockdown past 400 yards. But currently I only have visibility for clean shots up to about 175. This one was mostly passing through dense cover and never stopped for a good broadside shot. Given this current setup I figured a 50 yard zero would only make holdover an issue at about 175, which should be my first drop over about 3/4 in. Do you agree with this zero or think a longer zero and holding low would be more beneficial? Most of my < 150 shots here have much more clear visibility.

 

[Varminterror]

100yrd zero.