Hypothetical scenario about ballistics and range

[JohnnytheRipper]

I'm writing a book that involves a particular firefight between the protagonist and anti-hero, a rebel in a second Civil War torn United States, wielding a Zastava M76, and a US military designated marksman wielding a M21.

The scenario is that the two are in an undecided urban city, and are sniping at each other. The protagonist, let's call him Johnny, and the marksman, lets call him Matthew, start out at approximately 1.1km apart, and spot each other when Johnny's group assaults a squad. As the battle goes on and they keep trying to hit each other, they change positions, several times. but eventually they get close enough that Matthew fires a shot that destroys the ZRAK ON-M76 4x 5°10’ mounted on Johnny's M76. As a result, he is forced to use ironsights to fight Matthew.

My dilemma is at approximately what range would a 7.62x51 NATO bullet still shatter a metal and glass scope, but be stopped short of hitting the operator? I don't have the time or money to do range trials myself, so I'm asking members of THR to lend their wisdom on what range I should decide to handle this at? Some people may draw a parallel to Carlos Hathcock's amazing marksmanship that killed a Viet Cong through the scope, but the actual scene I'm taking this from is actually from a Japanese anime called Sword Art Online II.

I can provide more information as to the scenario if needed.

Thanks for the help!

 

[Inebriated]

at approximately what range would a 7.62x51 NATO bullet still shatter a metal and glass scope, but be stopped short of hitting the operator?

Pretty darn close...

 

[JohnnytheRipper]

Hmm. Well this wasn't done at long range, but I appreciate the insight. Perhaps if one knew the force required to shatter the scope lens, multiply it by two, and the compare muzzle energy of the ammo they give to designated marksmen I would have a decent grounded measurement.

 

[Inebriated]

Velocity and construction are what gets bullets through glass. Utilizing the same construction, as range increases, velocity decreases, and so do the chances of getting through the scope. So I don't know why you would need this test done at long range, if it didn't even get through at short range? Add to that the enormity of the scope you're talking about, and I think any further testing is... redundant.

 

[JohnnytheRipper]

I suppose so. I'll do some more research into it to be sure, and then I'll report back and cross check with other users on here regarding a few more questions about this scenario.

Thanks for the help!

 

[MistWolf]

With a little creative writing, you can have the bullet smash the scope without killing or injuring the protagonist, very believably, without worrying about range. The bullet could fragment, the shot is slightly off center, the bullet doesn't make it past the erector set, the bullet enters the objective, is deflected by the glass and exits the side of the tube, or the bullet enters the tube from the side and smashes a lens or the erector set. Make it simple and exciting without boring your reader with unneeded and unwanted details

 

[JohnnytheRipper]

Thanks for the tip. I just don't want the book to be scientifically inaccurate, and since I'm a stickler for detail and procedure, I wanted to ensure my knowledge of guns and engineering wasn't wasted. As I'm the student who in his first year of college did a report on ballistics of military rounds and went heavily into the subject to ensure proper procedure, safety, and control variables were set, I have an OCD about being believable when I write things.

 

[Bobson]

The trajectory is going to be a much more important factor than bullet energy. Even under 50 yards, the shot has to be perfectly lined up to completely pass through the scope and hurt/kill the operator behind it.

More importantly, I think, is making sure you don't make the battle leading up to this point too lengthy. A "designated marksman" with an M21 should be able to hit a still target at 1.1 km (roughly 3/5 of a mile) in 1-2 shots, and that's being generous. If it lasts for several shots, an informed reader might conclude that Johnny is facing the most incompetent designated marksman around.

Is this book going to be commercially available, or is it more of a project or personal pursuit? Sounds like a reasonably interesting (if not terribly unique) plot. I wouldn't be opposed to picking up a copy of it when available.

 

[JohnnytheRipper]

The book will *hopefully* be published commercially. I'm still writing and revising the first few chapters to 'glue' them together cohesively. After I establish how the flow is and have first drafts of each chapter, I'll have to meticulously comb over them for mistakes and such. Depending on the complexity I may need to hire a professional editor for it.

The aim of the book is to be a psychological thriller with some very strong themes presented throughout the story. If you're into games of any sort, the visual novel Chaos;Head apparently bears strong similarity to the writing style I'm going after, so I'm told. Never played it though.

Realistically I don't even know what publisher may publish it, as it contains strong violence, is told from the point of view of a young man who, in the midst of the second Civil War undergoes a psychological break, and depicts many atrocities that happen in the outbreak of the war in gory, realistic detail.

 

[Bobson]

So is this sort of your attempt to get into the world of commercial fiction, then?

If so, I wish you luck. Definitely not easy to get started, unless you're willing to fund yourself.

 

[JohnnytheRipper]

I make enough money through server administration that I don't necessarily need this to succeed, it is more of a test for me I suppose, an exercise in discipline and patience.

 

[taliv]

More importantly, I think, is making sure you don't make the battle leading up to this point too lengthy. A "designated marksman" with an M21 should be able to hit a still target at 1.1 km (roughly 3/5 of a mile) in 1-2 shots, and that's being generous. If it lasts for several shots, an informed reader might conclude that Johnny is facing the most incompetent designated marksman around.

that seems highly unlikely to me. most DM i know have very little precision rifle training and equipment that is adequate for shooting E types at that distance. I'd wager anyone remotely competent at designated marksmanship would be far more competent at moving and making use of cover. that means it's likely that the only shot they get on the other is either a moving target or a very small portion of a target. further, if you've ever walked between buildings in an undecided urban city, the wind is funneled and quite strong, but very localized so nearly impossible to detect the dozen or more different winds the bullet would encounter over that distance.

not easy shots.

btw, the carlos hathcock shot through the scope thing is so over done, reactions will probably range from eye rolling to vomiting. i'd probably put the book down at that point.

 

[d2wing]

The Zavasta is typically a 2.5 MOA at best and the M21 would be about 1-1.5 MOA maybe better. The M21 shooter should be able to make a head shot at 6-800 meters under good conditions. The Zavasta about 1/2 that. This is just guessing. A scope shot makes me groan. If you insist on it, the range to damage it could be anything. I doubt that you can shoot anyone in the eye through a scope, but it would be hard to hit the scope without hurting the guy behind it. Your rebel guy should be dead end of story. BTW I have shot an off the rack M-14 that shot 1/2 MOA issue ammo at a range. Several of us could hit man size pop-up targets out to 600 meters from prone with standard M-14s. Your Rebel guy would be dead long before he got in Zavasta range.

 

[Warp]

btw, the carlos hathcock shot through the scope thing is so over done, reactions will probably range from eye rolling to vomiting.

Seconded

 

[JohnnytheRipper]

As I said, I am not copying the Carlos Hathcock event from Vietnam. I am using it as a lead in to the climax, to instill fear in Johnny as he will know at that point he stands substantially outclassed. This is similar to, and a nod to Sword Art Online II, where deuteragonist Sinon faces a masked killer and also has her scope ruined. As the protagonist engages him in close range in a sword fight, she manages to fire a shot using her iron sights in order to give the protagonist the upper hand.

The first draft of the concept is mostly finished. Johnny and co, after arriving in the city in order to assault an enemy position, are soon gunned at by this marksman at roughly 1.1 kilometres from their target. He breaks off from the group to find a vantage point, from there he and the marksman exchange a few rounds, one of which shatters the scope. Due to deflection in the scope, the bullet exits out the right side of the rear, grazing him on the forehead. It is at this point that instinct takes over for him, and he abandons the position, ordering his crew to pin him down with fire from their DSHK machine gun while he moves closer. After a few light engagements on the streets using only the iron sights, he finds a partially destroyed apartment building to get a vantage point in, due to the smoke obscuring the marksman's vision. At roughly 500 metres, he fires several shots at the marksman, finally felling him with a shot to the lung.

I'm not going to divulge anymore because what happens next is in a state of flux, no concrete decision on how to handle the next part.

 

[chuckpro]

I applause you trying to be as technically accurate as possible. I think tho can make this go either way you want. But if you want at least some techinacl knolide watch this youtube video https://www.youtube.com/watch?v=D1U8YVWyMYY

I think there was a later video in which they used WW2 vintage scopes and got a pass through.

 

[earplug]

Testing at the range

Set up two pieces of target paper, space them the same distance as the scope is long. Put them down range at the distance your marksman is shooting.

The bullet will be coming down from its ballistic flight. I'm betting that the bullet would not be able to traverse the length of the scope due to the angle of entry.

 

[d2wing]

Sounds ok. I guess everyone is used to Hollywood shoot outs and those ranges for those weapons are reasonable. Keep at it and good luck. Sounds like an interesting story. Sometimes the mentality, training and experience makes all the difference. A DM with a more accurate weapon isn't likely to be a pushover.

 

[Nom de Forum]

If you want your book to remain credible I would reject the whole shooting through the scope thing. You will be just parroting a story that has become stale from other sources. Even the original source of the story has little remaining credibility.

 

[denton]

Without testing, it is impossible to say for sure, but it is likely that with some bullets, you get more penetration at lower impact speeds. It sounds backwards, I know. But if you look at a graph of hunting bullet penetration on the vertical axis vs. impact speed on the horizontal axis, the surprising thing is that the graph generally slopes downward to the right for hunting bullets.

At low impact speeds on big game, the bullet fails to open, and just pencils on through. You get a 30" skinny wound channel. At around 1800-2100 FPS, the curve flattens out and you get about 14-16" of penetration, and for common cup and core bullets, at around 2800 FPS the curve slopes down again because the bullet comes apart.

Mythbusters started with hollow point bullets, which are a very poor choice for penetration. In handguns, hollow points are needed so that the bullet will open. But rifle bullets are generally moving much faster, and the situation is very different. In rifles, hollow points open too much, too fast and come apart as they did in the Mythbusters video. Rifle hollow points are for target shooting only.

Military bullets tend to be non-expanding, full metal jacket and will behave more like the armor piercing bullet Mythbusters used toward the end.

 

[Warp]

Without testing, it is impossible to say for sure, but it is likely that with some bullets, you get more penetration at lower impact speeds. It sounds backwards, I know. But if you look at a graph of hunting bullet penetration on the vertical axis vs. impact speed on the horizontal axis, the surprising thing is that the graph generally slopes downward to the right for hunting bullets.

At low impact speeds on big game, the bullet fails to open, and just pencils on through. You get a 30" skinny wound channel. At around 1800-2100 FPS, the curve flattens out and you get about 14-16" of penetration, and for common cup and core bullets, at around 2800 FPS the curve slopes down again because the bullet comes apart.

Mythbusters started with hollow point bullets, which are a very poor choice for penetration. In handguns, hollow points are needed so that the bullet will open. But rifle bullets are generally moving much faster, and the situation is very different. In rifles, hollow points open too much, too fast and come apart as they did in the Mythbusters video. Rifle hollow points are for target shooting only.

Military bullets tend to be non-expanding, full metal jacket and will behave more like the armor piercing bullet Mythbusters used toward the end.

The part in bold is not quite true.

 

[denton]

Hmmmm..... searching my mind for an exception to the statement. I couldn't think of any at the time I wrote that. So, I'll bite: What's the exception? Maybe thinking of Barnes bullets?

 

[Warp]

Hmmmm..... searching my mind for an exception to the statement. I couldn't think of any at the time I wrote that. So, I'll bite: What's the exception? Maybe thinking of Barnes bullets?

There are a number of OTM and BTHP rifle rounds (I am most familiar with those in .223 and 5.56) that are very good choices for defensive use. Specific example: Hornady's 75gr BTHP in .223/5.56

And of course Barnes/TSX type hollow points.

 

[denton]

I think we agree on the Barnes exception, but disagree on the BTHP from Hornady.

Hornady lists it as a match bullet.

I'm sure that you could effectively defend yourself with the BTHP if you had to, but it's not designed for that use. Penetration is likely to be poor, as is bullet integrity after impact.

 

[allaroundhunter]

Denton, look up Hornady TAP FPD (for personal defense). A 75 gr BTHP is one of the bullets in the lineup. Also, the 77gr OTM round has proven to be a much better anti-personal round in the middle-east.

Also, there are plenty of hollow point rifle bullets used by varmint hunters. My coyote round is actually a 75 gr HP .243 Winchester.