Online version of Field Ballistics

About a year and half ago I upgraded my Windows hosting service from ASP.NET 3.5 to 4.5. This broke http://field.modernballistics.com.

I checked log files and, as I suspected, almost no one was using it. So I didn’t bother to fix it. I was using a beta version of Field Ballistics (or maybe even released it) and it was so much better that I didn’t even use the web version myself.

Today someone at a manufacturer of airgun pellets sent me an email saying they really liked it (I think they were referring to that version, English isn’t their native language) and wanted to know how much it would cost to support them. I asked about what sort of support they needed and then poked around on my website some. It turns out it was trivial to get it working again. So… in case anyone is interested here is a mobile friendly web based exterior ballistics calculator intended for use in the field.

Shooting a rifle upside down

Ry pointed out this thread to me on ARFCOM. Probably many people will want to stop at the picture and move on after that but the more interesting part to me is solving the sighting problem.

UpsideDownRifleShooting

Here is my thought process on the problem:

The drop is the same regardless of the gun orientation. Keep in mind that drop is independent of point of impact (POI) relative to point of aim (POA).

To solve this problem in general look up the drop for this range on the ballistics table for your ammo.

With the gun zeroed for this range the barrel is angled up such that it compensates for both the drop and the height of the sight (Sight Height or SH) above the bore.

Suppose the drop is 2 inches and the sight height is 1.5 inches. Hence the angle of the barrel is such that the bullet rises, relative to the muzzle, 3.5 inches between the muzzle and the target.

When you invert the gun you have the angle of the barrel giving 3.5 inches additional “drop” to the gravity induced drop for a total of 5.5 inches.

But you have the sight below the barrel which means you “get back” twice the sight height of the total. So the gun will be shooting -5.5 + (2 x 1.5) or 2.5” low.

Hence, the general solution for a gun zeroed at a given range when you turn it upside-down it will have a POI of:

POI = POA + SH – 2 x Drop

Or probably more useful is the POA relative to the POI:

POA = POI + (2 x Drop) – SH

1000 yard shot with 9mm

Update: From the comments I discovered Miculek used a 400 yard zero for his revolver, not the 200 yard zero I hypothesized. I have updated the post accordingly.


The other day Say Uncle posted this video of Jerry Miculek shooting at a balloon from 1000 yards away with a 9mm revolver:

First off, as Rivrdog noted, he didn’t hit the balloon. He hit the steel and the splatter from the bullet fragments popped the balloon.

Second, I decided to run the numbers on those shots. Using Modern Ballistics, the bullet Miculek said he used, with a muzzle velocity of 1000 fps (Hornady factory ammo with a four inch barrel is 975 fps but I added some extra velocity because Miculek probably has a longer barrel and a custom load), with a standard deviation of 10 fps, a bullet delivering a five shot group size of 1 MOA under ideal conditions, a wind estimation error of 0.2 MPH, sea level, at 59F, and a 400 yard zero. We end up with the following results.

The bullet took 5.11 seconds to travel the 1000 yards. It reached a height of 110 feet at 583 yards from the shooter. It arrived at a velocity of 377 fps.

This first graph shows the height in inches from the point of aim. At the target the bullet is hitting over 2900 inches low. That is over 240 feet below the point of aim!

Drop10To1000

In this graph the rate of descent at the 1000 yard mark is shown. That is nearly 11 inches of additional drop for each yard of travel.

Drop990To1010

Here we have the odds of getting a hit if the shooter knew the exact ballistics and compensates perfectly for every shot. The random variation of the muzzle velocity, wind variation (Gaussian distribution with a standard deviation of 0.2 MPH), and inherent variations in the bullet contribute enough error that only about a third of the bullets would hit a target 30 inches wide and 50 inches tall.

TargetView

The image below is what the shooter would see with a red-dot sight shooting a tracer bullet with the same drag. I added some wind to make the perspective a little better. At 1.6 yards the bullet crosses the near zero and you can see the red-dot of the sight just before the track of the tracer starts. The tracer ignites at 2 yards. Everything is to scale so change the size of the image such that the base of the 9mm bullet looks the same in the image as a 9mm bullet would at 1.6 yards and you can see what the 30 x 50 inch target would look like at 1000 yards.

TracerView

Jerry is at the peak of human shooting ability but he had some serious luck on that shot.

Windows Phone app reviews

My two Windows Phone apps have some reviews now. All are five stars!

For As the Crow Flies:

  • by Antonio
    5/18/2014

    Thank you for this app. Useful for me as a firefighter because I can only live a certain distance from the firehouse “as the crow flies” so this app very useful. Simple but worked perfectly.

  • by Kevin
    4/12/2014

    Very accurate, easy to use.

For Field Ballistics:

  • by Bryan
    5/1/2014

    Seriously a cool app for shooters.

“Messin’ around shooting” with carry pistols

My friends and I, as a natural matter of course, sometimes try our carry or service pistols at 100 or even 200 yards. It’s always seemed to me an obvious thing to try. Why wouldn’t you?

And so when Oleg and I were out “messin’ around shooting” at various rocks, dirt clods, sticks and whatnot at various random distances, we did some 100 yard pistol shooting with our carry pistols (a 9 mmP and a 10 mm Auto).

I haven’t commented on this phenomenon before, but I’ve noticed that the point of hold for 100 yards with a Glock 20 isn’t much different from that at 25 yards. It was when Oleg, without any prompting, made the same observation regarding his 9 mm carry pistol that it occurred to me to say so in a post. Well here it is.

Oleg was striking a roughly 8″ square plate at 100 yards with successive shots from his 9mm Glock.

I don’t know what utility this sort of pistol shooting might have in defense, but it is good to know you can do it.

Cut lead bar verses round ball

I’d not heard of cut lead bar being used in lieu of ball. The use of “findings” in a fowling piece or a blunderbuss, sure, but not this. Interesting.

If you can melt lead or a similar metal or alloy (and who can’t?) and pour it into a slot between some boards, you have buckshot for your scattergun, or bullets for your “smooth rifle”.

I wouldn’t try it on the line at Boomershoot though. Well OK I might, but I wouldn’t expect any detonations, much less hits, from 400 yards.

1939 LA County sheriff’s revolver club

From an e-mail.

The PC police would of course disapprove of the cigarettes and cigar. OK they’d disapprove of everything.

Also they handle lead with their bare hands at the range, shoot stuff out of other people’s mouths and ears which our litigious society now largely prevents, and they still for some reason thought the human heart was all in the left side of the chest. It appears that the price of their cast lead bullet reloads was a penny per round (presumably with the deposit of your spent brass).

They had someone else to clean your gun for you. That I do not approve– It’s not only elitist, but dumb from the standpoint of being able to understand and monitor the condition your own hardware. You should clean your own gun as an integral part of the craft.

They did have rotary, progressive loading machines.

I understand the desire for efficiency at a range, and of having some kind of standards for evaluating the skills of your deputies, but the highly controlled (and therefore highly limited) nature of the training/practice experience at such a range leaves me somewhat cold. I suppose it makes me something of an outlier, but I think you should to get out and simply “play” at it now and then, making up your own scenarios, picking non-standard targets at un-measured distances and so on. I’ll call this “messin’ around shooting”.

I once had a retired LA cop (which means he should very well know better from more than a little personal experience) tell me that his 45 ACP could “shoot through an engine block”. When I got back into shooting after being a hippie for a while, one of the first things I did, of course, was to try various calibers on an old chainsaw at a friend’s house. A 9 mm Para would break the aluminum fins off the cylinder, a 10 mm would strip the fins down clean, and a 7.62 x 39 would punch through the light aluminum and severely dent or tear the steel parts. There’s no way your 45 is going to “shoot through an engine block”. The messin’ around shooter already knows this from direct experience.

So while the gelatin testers, the organized range shooters and the gun magazine readers are talking about the performance of this or that bullet or load, the hunter who does his own butchering, and the messin’ around shooter, are often scratching their heads laughing at them.

I know people who are far more concerned about keeping the grass at the range looking nice than having year-round access for shooters, and they hate people like me. If it’s your own private club and your dime, fine.

Man; I got a little distracted there, huh?

Ammo for 3-D printed guns

The plastic guns being made have been tested with conventional ammo intended to be fired in conventional guns. Why not load up some low pressure rounds specifically intended to work with the plastic guns?

Even if the bullets had muzzle velocities half that of conventional guns you aren’t going to get volunteers to be bullet backstops. Choose a common cartridge which already has a fairly low pressure then tweak the bullet weight and powder charge to get something that the plastic is much more capable of handling.

Here is a list of max pressure recommendations in PSI for various cartridges with the obvious high pressure cartridges removed:

380 Auto 21,500
25 Auto 25,000
32 S&W Long 15,000
38 Auto 26,500
38 S&W 14,500
38 Special 17,000
44 S&W Spl 15,500
45 Auto 21,000
45 Colt 14,000

I’m a “respected Idaho based shooter and author”

Apparently I’m now “a respected Idaho based shooter and author.”

The background story is that I and several other bloggers were asked by the folks at AmmoForSale.com which of the three major calibers, 9mm, .40 S&W, and .45 ACP, was the best. I answered, via the blog post, and they just posted an article that incorporates some of my response.

I appreciate the kind words but I’m not sure I have all that much respect as a shooter compared to a lot of other people and I’m a “software author”, blogger, and occasional magazine article writer. I’m not really an “author” in the most common sense.

Still, I think they did a good job on their article even if they did give me more credit than I think I’m due.

More on “Barrel Harmonics”

There is incontrovertible proof that those who talk about barrel harmonics do not know what they’re talking about, and that proof is in the very term they use to talk about it.

First; the term “harmonic” is a very specific term for an integral multiple of a fundamental vibration frequency. Since a barrel is (usually) a somewhat irregular object tethered at one end, I question whether most of them have a harmonic overtone series at all (like a guitar string or the air column inside a flute) or a primarily inharmonic one, like a bell or a cymbal. “You keep using that word…”

Second; the fundamental frequency of the “resonating” barrel is being ignored (by the language at least) yet the fundamental is often, or probably, more significant, i.e. it probably has a higher amplitude than the higher frequency vibrations. That’s usually very much the case with a vibrating body unless it’s being dampened at the fundamental. So why, particularly, are we discussing overtones (harmonic ones or inharmonic ones) and not the fundamental?

Third; don’t even talk to me about barrel harmonics, or barrel fundamental vibration, or inharmonic barrel overtones (A.K.A. “partials”) on an AK or a 30 Carbine, et al barrel. Just don’t.

I once had to do this with a class of music majors during a seminar I did at the U of Idaho. We were talking about advanced tweaks, the last one percent, of what goes into the design and structure of a musical instrument to make it a really fine one, and the students were responding as though I were talking about major issues. My fault. I should have been more clear at the outset.

So here it is; you don’t address the last one percent on your AK. It’s not a beanfield rifle. Please. There are several other factors that totally overwhelm the last one percent (like the previous 99 for example) and so if you address the last one percent as though it were “the issue” you’re ignoring the issues that matter.

Low-speed heavy bullet expansion

I was pondering my earlier experience with bullet performance, and got to wondering about the other end of things, with low-velocity rifle bullets. When shooting at very long ranges, or when using a subsonic cartridge like a 300 Blackout / Whisper, what heavy .30 cal bullets expand reliably at around 1000 fps? Obviously something like a 200 grain Nosler Partition will hold together, but will it mushroom at all at low velocity? They only brag about expansion down to 1800 fps on their Ballistic Tip, which only goes to 180 gr. Their “long range” Accubond recommends greater than 1300 FPS. Now, with a BC of .730 in a 210 gr Spitzer it’s still going to hurt what it hits, but if you want to maximize energy transfer, punching a neat hole isn’t the way to do it.

Any thoughts, experience, recommendations, or rumors?

Field Ballistics bug fix

I fixed a minor bug in Field Ballistics. The new version is 1.1.1.0. It is available on the Windows Phone store now.

The bug was that under certain situations you could delete the last target. Other places in the app required that at least one target exist at all times. After deleting the last target the app would immediately crash.

As a side note: I submitted the changed version Sunday evening. It made it through Microsoft certification in less than three days.

Field Ballistics update

I released a new version of Field Ballistics for Windows Phone earlier this week and it made it through Microsoft’s test gauntlet this morning.

Here are the changes in version 1.1:

A crash that occurred when measuring inclines has been fixed.

Auto conditions retrieves air pressure from the weather service and allows manual input of air pressure independent from altitude for user defined conditions.

Target range can now be set in the range edit box in addition to moving the target push pin on the map.

Probable bug in Windows Phone 8

I found what appears to be a minor bug in some Windows Phone 8 devices.

It showed up in my Field Ballistics program. I have code that looks like this:

// Can we focus only on the target?
if (this.cam.IsFocusAtPointSupported)
{
    this.cam.FocusAtPoint(0.5, 0.5);
}
else
{
    this.cam.Focus();
}

On someone’s phone this raised a “System.InvalidOperationException” on the call to “FocusAtPoint”.

What appears to have happened is that the phone reports IsFocusAtPointSupported as “true” but doesn’t actually support it. It’s not all that big of deal but it does mean I’ll be releasing an update a little sooner than I had planned.

Hat tip; theBlaze

Happy Independence Day.

He probably complied too much, and should have stood his ground on the “Am I being detained” part. I don’t know what I will do when my time comes, but I have been through a similar incident before and it left a bad taste in my mouth. In that case I was in fact in violation, by having studded tires after the deadline for removing them. If I were totally innocent, who knows what would happen? I’ve seen the dog trick before too. It’s bullshit. I do know for sure that I will be asking the criminal posing as a cop to get out a pad and pencil and jot down “18 USC 241″ and “18 USC 242″ and informing him that he is putting himself at risk for prosecution.

A dashcam would be a good investment about now, to document the crimes committed by corrupt police, if for no other reason than posterity, so future generations can see how and when our republic fell into the shithole.