May 4th, 2017

Get Most Popular Ballistics App for iOS at Half Price

Ballistic AE Moble App Ballistics Program solver JBM iphone, iPod, iPad

Ballistic AE Moble App Ballistics Program solver JBM iphone, iPod, iPadNeed a top-notch Ballistics App for your iPhone, iPad, or iPod? Start with Ballistic AE, the number 1 (i.e. most installed) App for iOS systems. Ballistics AE (Advanced Edition) is the most popular iOS ballistics program for many good reasons. Full-featured and easy to use, Ballistics AE has been refined over many years, and it supplies rock-solid solutions derived from JBM Ballistics solver (created by James B. Millard). Unlike some other Apps, Ballistics AE is STABLE on iPhones (with various OS levels). What’s cool is that Ballistics AE is now on sale for $12.99.

We’ve used the Ballistic AE program on an iPhone 5S, iPhone 6, and iPad, and it performed well. Here are some of the features we liked:

  • 1. Mirrors output from online version of JBM Ballistics we often use for initial calculations.
  • 2. Controls are simple to use and (mostly) intuitive.
  • 3. Handy comparison feature lets you compare ballistics for different projectiles side by side.
  • 4. Advanced Wind Kit allows you to account for complex wind situations.
  • 5. Projectile and BC Database is very comprehensive.
  • 6. Software is regularly updated to match Apple OS changes.

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Ballistic AE Moble App Ballistics Program solver JBM iphone, iPod, iPad

Comprehensive Projectile Info and BCs
Ballistics AE has very complete data libraries. The program includes 5,000 projectiles, factory loads, military loads, and performance data points from leading manufacturers, military testing, and performance testing.

Ballistic Coefficient libraries include the latest commercial BC data, plus Applied Ballistics’ (Bryan Litz) custom G7 BCs, plus G7 military coefficients from Aberdeen Proving Grounds.

Ballistic AE Moble App Ballistics Program solver JBM iphone, iPod, iPad

These Videos Explain How to Set Up and Use Ballistic AE:

Permalink Bullets, Brass, Ammo, Gear Review, Hot Deals 1 Comment »
February 17th, 2015

Brain Teaser: Do You Know the Rule of the Square?

wind drift wind reading 6mmbr rule of the squareHorizontal Wind-Drift vs. Distance
OK, here’s a challenge question for you.
Let’s see if you get it right.

Q: If the wind is blowing 10 mph from 9 o’clock and if my horizontal wind deflection is 0.7 inches at 100 yards, what is the horizontal drift at 1000 yards?

You may be thinking, “Well, since the target is ten times more distant, the wind-drift should be around 7 inches, maybe a little more since the bullet will be slowing down.” That sounds reasonable, right?

WRONG.

As you move from near to far, the increase in lateral deflection (from a 90° crosswind) is (roughly speaking) a function of the square of the multiple of distance. If your target is two times farther away, you use the square of two, namely four. If your target is five times farther away, you use the square of five, or twenty-five. In this example, the increased wind drift (from 100 to 1000 yards) is at least 0.7″ times (10 X 10) — over 70 inches (give or take a few inches depending on bullet type). We call that the Rule of the Square. This Rule lets you make a quick approximation of the windage correction needed at any yardage.

Precision Shooting and the Rule of the Square
I was going through some back issues of Precision Shooting Magazine and found many references to the Rule of the Square. This made me curious — I wondered how well the Rule really stacked up against modern ballistics programs. Accordingly, I ran some examples through the JBM Ballistics Trajectory Calculator, one of the best web-based ballistics programs. To my surprise, the Rule of the Square does a pretty good job of describing things.

EXAMPLE ONE — .308 Win (100 to 400 Yards)
For a 168gr Sierra MK (.308), leaving the muzzle at 2700 fps, the JBM-predicted values* are as follows, with a 10 mph, 9 o’clock crosswind (at sea level, 65° F, Litz G7 BC):

Drift at 100: 0.8 MOA (0.8″)
Drift at 200: 1.6 MOA (3.3″)
Drift at 400: 3.4 MOA (14.4″)

Here you can see how the Rule of the Square works. The rule says our drift at 200 yards should be about FOUR times the drift at 100. It the example above, 0.8″ times 4 is 3.2″, pretty darn close to the JBM prediction of 3.3″. Quoting Precision Shooting: “Note that the deflections at 100 yards are typically a quarter of those at 200; lateral deflections increase as the square of the range”. Precision Shooting, June 2000, p. 16.

EXAMPLE TWO — .284 Win (100 to 1000 Yards)
For a .284 Win load, with the slippery Berger 180gr Target Hybrids, the Rule of the Square still works. Here we’ll input a 2750 fps velocity, Litz G7 BC, 10 mph, 9 o’clock crosswind, (same 65° temp at sea level). With these variables, JBM predicts:

Drift at 100: 0.5 MOA (0.5″)
Drift at 500: 2.5 MOA (13.3″)
Drift at 1000: 5.9 MOA (61.3″)

Again, even with a higher BC bullet, at 1000 yards we end up with something reasonably close to the 100-yard deflection (i.e. 0.5″) multiplied by (10×10), i.e. 50 inches. The Rule of the Square alerts you to the fact that the effects of crosswinds are MUCH greater at very long range. In this example, our JBM-calculated drift at 1000 is 61.3″ — that’s over 100 times the 100-yard lateral drift, even though the distance has only increased 10 times.

Note that, even with a 5 mph 90° sidewind, the “Rule of the Square” still applies. The 1000-yard lateral deflection in inches is still over 100 times the lateral deflection at 100 yards.


Why This All Matters (Even in the Age of Smartphones)
wind drift wind reading 6mmbr rule of the squareNow, some would say, “Why Should I Care About the Rule of the Square? My iPhone has a Ballistics App that does all my thinking for me”. Fair enough, but knowledge of this basic Rule of the Square enables a shooter to make an informed guess about necessary windage even without a come-up sheet, as long as he knows the distance AND can fire a sighter at 100 or 200 yards as a baseline.

For example, if I see empirically that I need 1″ windage correction at 100 yards, then I know that at 600 yards I need at least roughly (6 x 6 x 1″) or 36 total inches of drift correction, or 6 MOA. (To be precise, 1 MOA = 1.047″ at 100 yards). I can figure that out instantly, even without a ballistics chart, and even if my Smartphone’s battery is dead.

*Values shown are as displayed on the JBM-figured trajectory tables. The numbers can be slightly imprecise because JBM rounds off to one decimal place for both inches and MOA.

Permalink Shooting Skills, Tech Tip 2 Comments »
February 1st, 2015

Over-Shooting the Berm — When a Mere 5 Degrees Can Be Deadly

In our Shooters’ Forum, there was an discussion about a range that was threatened with closure because rifle over-shoots were hitting a farm building over two miles from the firing line. One reader was skeptical of this, asking “how’s that possible — were these guys aiming at the stars?” Actually, you may be surprised. It doesn’t take much up-angle on a rifle to have a bullet land miles down-range. That’s why it’s so important that hunters and target shooters always orient their barrels in a safe direction (and angle). Shooters may not realize how much a small tilt of the barrel (above horizontal) can alter a bullet’s trajectory.

How many degrees of muzzle elevation do you think it would take to hit a barn at 3000 yards? Ten Degrees? Twenty Degrees? Actually the answer is much less — for a typical hunting cartridge, five to seven degrees of up-angle on the rifle is enough to create a trajectory that will have your bullet impacting at 3000 yards — that’s 1.7 miles away!

Five degrees isn’t much at all. Look at the diagram below. The angle actually displayed for the up-tilted rifle is a true 5.07 degrees (above horizontal). Using JBM Ballistics, we calculated 5.07° as the angle that would produce a 3000-yard impact with a 185gr .30-caliber bullet launched at 2850 fps MV. That would be a moderate “book load” for a .300 Win Mag deer rifle.

Gun Angle long range

Here’s how we derived the angle value. Using Litz-derived BCs for a 185gr Berger Hunting VLD launched at 2850 fps, the drop at 3000 yards is 304.1 MOA (Minutes of Angle), assuming a 100-yard zero. This was calculated using a G7 BC with the JBM Ballistics Program. There are 60 MOA for each 1 degree of Angle. Thus, 304.1 MOA equals 5.068 degrees. So, that means that if you tilt up your muzzle just slightly over five degrees, your 185gr bullet (2850 fps MV) will impact 3000 yards down-range.

Gun Angle long range

Figuring Trajectories with Different Bullets and MVs
If the bullet travels slower, or if you shoot a bullet with a lower BC, the angle elevation required for a 3000-yard impact goes up, but the principle is the same. Let’s say you have a 168gr HPBT MatchKing launched at 2750 fps MV from a .308 Winchester. (That’s a typical tactical load.) With a 100-yard zero, the total drop is 440.1 MOA, or 7.335 degrees. That’s more up-tilt than our example above, but seven degrees is still not that much, when you consider how a rifle might be handled during a negligent discharge. Think about a hunter getting into position for a prone shot. If careless, he could easily touch off the trigger with a muzzle up-angle of 10 degrees or more. Even when shooting from the bench, there is the possibility of discharging a rifle before the gun is leveled, sending the shot over the berm and, potentially, thousands of yards down-range.

Hopefully this article has shown folks that a very small amount of barrel elevation can make a huge difference in your bullet’s trajectory, and where it eventually lands. Nobody wants to put holes in a distant neighbor’s house, or worse yet, have the shot cause injury. Let’s go back to our original example of a 185gr bullet with a MV of 2850 fps. According to JBM, this projectile will still be traveling 687 fps at 3000 yards, with 193.7 ft/lbs of retained energy at that distance. That’s more than enough energy to be deadly.

Permalink Shooting Skills, Tech Tip 13 Comments »
October 19th, 2014

How Altitude and Air Pressure Influence Ballistics

Suunto AltimeterOne of our readers asked “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.

Forum member Milanuk explains that the key factor is not altitude, but rather air pressure. Milanuk writes:

“In basic terms, as your altitude increases, the density of the air the bullet must travel through decreases, thereby reducing the drag on the bullet. Generally, the higher the altitude, the less the bullet will drop. For example, I shoot at a couple ranges here in the Pacific Northwest. Both are at 1000′ ASL or less. I’ll need about 29-30 MOA to get from 100 yard to 1000 yards with a Berger 155gr VLD @ 2960fps. By contrast, in Raton, NM, located at 6600′ ASL, I’ll only need about 24-25 MOA to do the same. That’s a significant difference.

Note that it is the barometric pressure that really matters, not simply the nominal altitude. The barometric pressure will indicate the reduced pressure from a higher altitude, but it will also show you the pressure changes as a front moves in, etc. which can play havoc w/ your calculated come-ups. Most altimeters are simply barometers that read in feet instead of inches of mercury.”

As Milanuk states, it is NOT altitude per se, but the LOCAL barometric pressure (sometimes called “station pressure”) that is key. The two atmospheric conditions that most effect bullet flight are air temperature, and barometric pressure. Normally, humidity has a negligible effect.

It’s important to remember that the barometric pressure reported on the radio (or internet) may be stated as a sea level equivalency. So in Denver (at 6,000 feet amsl), if the local pressure is 24″, the radio will report the barometric pressure to be 30″. If you do high altitude shooting at long range, bring along a Kestral, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 feet.”

You can do your own experimental calculations using JBM Online Ballistics (free to use). Here is an extreme example, with two printouts (generated with Point Blank software), one showing bullet trajectory at sea level (0′ altitude) and one at 20,000 feet. For demonstration sake, we assigned a low 0.2 BC to the bullet, with a velocity of 3000 fps.

Trajectory of Bullet fired at Sea Level

Trajectory of Bullet fired at 20,000 feet

if you want to learn more about all aspects of External Ballistics, ExteriorBallistics.com provides a variety of useful resources. In particular, on that site, Section 3.1 of the Sierra Manual is reprinted, covering Effects of Altitude and Atmospheric Pressure on bullet flight.

Permalink Tech Tip 5 Comments »
January 7th, 2013

G1 vs. G7 Ballistic Coefficients — What You Need to Know

The better, up-to-date ballistics programs let you select either G1 or G7 Ballistic Coefficient (BC) values when calculating a trajectory. The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. You’ve probably seen that G7 values are numerically lower than G1 values for the same bullet (typically). But that doesn’t mean you should select a G1 value simply because it is higher.

Some readers are not quite sure about the difference between G1 and G7 models. One forum member wrote us: “I went on the JBM Ballistics website to use the web-based Trajectory Calculator and when I got to the part that gives you a choice to choose between G1 and G7 BC, I was stumped. What determines how, or which one to use?”

The simple answer to that is the G1 value normally works better for shorter flat-based bullets, while the G7 value should work better for longer, boat-tailed bullets.

G1 vs. G7 Ballistic Coefficients — Which Is Right for You?
G1 and G7 refer both refer to aerodynamic drag models based on particular “standard projectile” shapes. The G1 shape looks like a flat-based bullet. The G7 shape is quite different, and better approximates the geometry of a modern long-range bullet. So, when choosing your drag model, G1 is preferrable for flat-based bullets, while G7 is ordinarily a “better fit” for longer, boat-tailed bullets.

G1 G7 Ballistic coefficients

Drag Models — G7 is better than G1 for Long-Range Bullets
Many ballistics programs still offer only the default G1 drag model. Bryan Litz, author of Applied Ballistics for Long Range Shooting, believes the G7 standard is preferrable for long-range, low-drag bullets: “Part of the reason there is so much ‘slop’ in advertised BCs is because they’re referenced to the G1 standard which is very speed sensitive. The G7 standard is more appropriate for long range bullets. Here’s the results of my testing on two low-drag, long-range boat-tail bullets, so you can see how the G1 and G7 Ballistic coefficients compare:

G1 BCs, averaged between 1500 fps and 3000 fps:
Berger 180 VLD: 0.659 lb/in²
JLK 180: 0.645 lb/in²

The reason the BC for the JLK is less is mostly because the meplat was significantly larger on the particular lot that I tested (0.075″ vs 0.059″; see attached drawings).

For bullets like these, it’s much better to use the G7 standard. The following BCs are referenced to the G7 standard, and are constant for all speeds.

G7 BCs:
Berger 180 VLD: 0.337 lb/in²
JLK 180: 0.330 lb/in²

Many modern ballistics programs, including the free online JBM Ballistics Program, are able to use BCs referenced to G7 standards. When available, these BCs are more appropriate for long range bullets, according to Bryan.

[Editor’s NOTE: BCs are normally reported simply as an 0.XXX number. The lb/in² tag applies to all BCs, but is commonly left off for simplicity.]

Permalink Bullets, Brass, Ammo, Reloading 20 Comments »
November 22nd, 2010

New .224-Cal Varmint Bullets From Hornady

We recently had a chance to chat with Dave Emary, Hornady’s Chief Ballistics Scientist. Dave told us that varmint hunters should definitely check out two new .224-caliber bullets from Hornady, the 35gr NTX and the 53gr V-Max. Both bullets offer high-BCs for their weight class, along with excellent terminal performance.

New Lead-Free NTX “California-Legal” Bullet
First is the new 35gr NTX® BT plastic-tipped bullet. This is a lead-free California-compliant design. Designed with a boat-tail and extended ogive, the new 35gr NTX has better ballistics than most other bullets in its weight class. This bullet can be pushed to very high velocities by a standard .223 Remington cartridge. As you can see from the factory illustrations below, the new 35gr NTX bullet is far more streamlined that the previous 35gr flat-base V-MAX, and the NTX’s BC is much higher. So the NTX gives you a lead-free alternative, that has better ballistics to boot.

Hornady NTX bullet

New High-BC, 53gr V-Max May Be a “Game-Changer” for .223 Rem Shooters
The second recently-released bullet is a new, High-BC, 53gr V-Max with a field-tested 0.290 G1 Ballistic Coefficient. That’s a very high BC for a .224-caliber bullet in this weight class. To demonstrate that point, the Berger 55gr BTHP Varmint bullet has a .210 G1 BC, while the Sierra 53gr FB MatchKing has a .224 G1 BC (above 2800 fps). How did Hornady achieve the higher BC? Emary tells us that this new bullet was designed with an extended ogive (nose section) to provide significantly better ballistics than other bullets in its weight class. Emary added: “With this .290 BC bullet and the higher velocities we get with the SuperFormance powder blends, the .223 Remington runs pretty darn close to a .22-250 with standard loads — you can run the ballistics numbers yourself.”

Hornady V-Max 53

Taking Up Emary’s Challenge — Running the Balllistics
Given Dave’s challenge to “run the numbers” — we did just that. Hornady claims 3465 fps from its new SuperFormance .223 Rem factory ammo loaded with the 53gr V-Max. At 400 yards, this load will drop 20.8 inches from a 100-yard zero, and drift 15.6 inches in a 10 mph crosswind. (Figures calculated with JBM Ballistics, for 500′ altitude, 70° F.) To compare, Hodgdon’s Reloading Data Center says a .22-250 can deliver 3713 fps with a 55-grainer pushed by a max load of IMR 4064. So, for the .22-250, assuming a .220 BC for the 55gr bullet, the drop at 400 yards (from 100-yard zero) is 20.4 inches, while the 10 mph wind drift is 20.2 inches (again according to JBM). So, it looks like Emary is right, assuming his .223 Rem velocities are real. At 400 yards, the .223 Rem with the 53-grainer has nearly identical drop and much less wind drift than a .22-250 shooting a conventional 55-grainer. Here are the numbers:

Cartridge Muzzle Vel Bullet BC Drop at 400 yds Drift at 400 yds
.223 Rem 3465 fps 0.290 BC (53gr) 20.8 inches 15.6 inches
.22-250 3713 fps 0.220 BC (55gr) 20.4 inches 20.2 inches

We asked Emary how the new 53-grainers hold up when driven at high velocities. Emary replied: “The 53-grainer has the tough V-Max jacket. You should be able to push it up to 4000 fps with no problems”.

Permalink Bullets, Brass, Ammo, Hunting/Varminting, New Product 6 Comments »