Simple question: can a military sniper rifle fire through a glass pane and be expected to hit the target, or will the impact on the glass divert the bullet’s trajectory, or slow the bullet down? Will a sniper avoid shooting through a window or is it just another day at the office?
I assume that you are talking about firing through a window a short distance from the rifle, rather than near the target. Provided that the target is not too far past a window, the change in the bullet’s path would not be significant.
In the case of a window right in front of a sniper, it would definitely be avoided as the bullet’s trajectory would be greatly altered. I think there was a movie at one point where a dab of explosive was put on a window so that a split second before the rifle fired the window was shattered. Presumably the puff of air out of the muzzle of the gun would blow the glass shards enough to avoid changing the path of the bullet.
I was actually thinking about a window close to the target but a long way away from the sniper. That wouldn’t pose a significant difficulty?
Based on what I recall from John Plaster’s Ultimate Sniper: An Advanced Training Manual for Military and Police Snipers, shooting through glass will deflect the bullet. It will slow the bullet slightly, but also cause it to tumble instead of spiralling like it should be. If this happens at the shooter end (i.e. sniper concealed in a building, shoots through the window), then the shot will be very far off target. If the glass is at the target end then the shot will still be off, but not by as much (less distance to travel after being disrupted). However, the window could shatter, sending glass fragments into the room. So, long story short: Don’t shoot through glass if it’s at your end, don’t shoot through if there are people/things in the room that you don’t want injured/damaged.
Why do you wish to know, does your office have a good “view”? 
I will say first off that I am not a sniper (surprise!), so there may be one (sniper) out there that would shoot through a window but…
It would seem like a bad idea to do so.
Though glass provides (relatively) little resistance to a bullet travelling through it at 600 m/s (or whatever a sniper bullet would travel), keep in mind that you don’t need much force to affect the rotation of the bullet. Glass (or any change between media) can have this effect upon bullets. Once you change the rotation of the bullet it will alter tragectory accordingly. This may not happen all of the time (or to a significant degree) of course (maybe not even most of the time), but I think a sniper would wish to increase his odds in every situation.
As a side note, the shattering of the glass would give away a sniper’s position quite distinctly, also a bad idea (though I really don’t think this was the point of your question, it is important to the whole point of sniping).
Good shooting.
Hmmm, I was assuming the shooter near the window… probably not as big of a change in bullet tragectory if the glass is close to the target.
I’m pretty sure that I recall seeing this in The Negotiator. In the opening sequence, they take out the guy holding a girl hostage in his apartment. Good ole’ Samuel L Jackson comes in and draws him into the sniper’s line of fire, upon which they set off the explosive, shattering the window, and then they shoot him (in the leg? Or was it his shoulder?). Is this the film you’re thinking of?
Here’s an account of a Canadian (a Newfie, no less) sniper hitting an al-Qaeda gunman from a distance of nearly 2.5 kilometers. Here’s the kicker: the gunman was hiding behind a piece of corrugated metal. The sniper shot right through the metal with his MacMillan Tac-50.
-Apoptosis
Also of concern is the angle of the glass to the path of the round. If the pane is just in front of the target, and approximately at a right angle, normal window glass will have almost no effect. In fact, with a very powerful round, even more obdurate materials will have little effect, if there is a short distance, and a right angle to the shooter.
With a higher incident angle, deflection will be much greater, even in the case of glass. Once that deflection has occurred, distance from that point to the target is critical, although a distance less than a meter is less likely to cause a complete miss. Precision placement is not possible through obstacles.
More often than explosives, Sniper teams use two shots, one to shatter the glass, followed immediately by a shot for effect, which passes through the hole, to the target. Brittle materials like glass will leave a sufficiently large hole, even when reinforced by wire, or plastic. The second sniper shoots at the place where the hole will be, rather than waiting for the round to strike. His shot, if the team is well trained, will arrive before the target moves enough to cause a miss.
Tris
Pros don’t take chances. I can’t remember the book, but they work as a team. First man breaks the pane and the second fires immediately to take out the target.
There are types of bullets that are affected less by going through glass than others, but they are all affected to some degree.
In Patriot Games or Cardinal in the Kremlin, Clancy writes about this scenario, with one sniper shooting a fraction of a second before another, to break the glass for the second round. I don’t think this would be police SOP, for the simple reason that you just don’t know what that first bullet is going to do after it hits the glass. Doesn’t do you much good to drop the baddie, if you also put a 168gr SMK through the noggin of the hostage.
That’s in Cardinal, Brutus(just so you know), when the HRT is saving Al Gregory from his kidnappers. I was thinking of the exact same scene when I opened this topic.
Firing through glass isn’t good because glass can:
a) deflect the bullet
b) cause the bullet to fragment
Either one means that you’re not likely to hit or even seriously injure your target.
Sacramento dopers (believe it was in Sacramento) may well remember the hostage standoff at a Good Guy’s store a few years ago. When the front door was opened so a hostage could retrieve body armor the suspects demanded, the SWAT team made their move and a sniper took a shot through the open door at a suspect. Unfortunately, the door was closing and the bullet hit the glass, only wounding the suspect.
I’ve seen steel core 7.62 rounds from an AK-47 come apart going through standard window glass. It’s not a substance you want to shoot through when lives are on the line.
–Patch
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- A buddy was a sniper in the marines–he said it partly depends on the glass type, and partly on the angle you are shooting through the glass. Ordinary household window glass can be shot through at any old angle because it is so weak, it hardly matters. The “problem” glass is safety-laminated types, such as automobile front and rear windows, and the glass panels typically used in doors and see-through walls of modern office buildings. If you can shoot straight-through (perpendicular to) laminated glass, it isn’t much of a problem, normally–but if you have to shoot through it at an angle, it can deflect a 30-cal bullet enough that a human target standing only a few feet from the other side of it can be missed entirely (this is assuming that the glass is some distance away from the shooter, and the target is sanding a few feet on the opposite side of the glass)…
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- The exception when they don’t like shooting at all through glass is when the target is wearing body armor–as said, glass often slices up bullet jackets and causes bullets to tumble, and both these things can ruin their penetration through bulletproof armor materials where normally they would sail right through.
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