View Full Version : 5.56 vs. auto glass test
We happened upon a piece of what I think is auto glass this morning. So I took the opportunity to do some informal research that I had been promissing to do in another thread.
I used stuff that we found out at the range since I wasn't planning on doing this test today. The 3/4" plywood was used to tape my targets to so I could guage any deflection, and get an idea of what kind of penetration the round would have after it passed thru the glass.
Weapon used had a 14.5 inch barrel. I fired from about 7 yards away.
The first round tested was Federal NT frangible. The stuff that you can get from Ammoman.com.
http://i210.photobucket.com/albums/bb201/trixiebud/hudson007.jpg?t=1215199735
The Frangible passed through the glass and appears to have broken into two main chunks that both penetrated the 3/4" plywood. No deflection at all.
http://i210.photobucket.com/albums/bb201/trixiebud/hudson008.jpg?t=1215200164
The second round is XM193. (second target taped to capture any deflection)
http://i210.photobucket.com/albums/bb201/trixiebud/hudson009.jpg?t=1215200374
The M193 didn't appear to break. But it didn't pass through the backstop cleanly at all. It's the second exit hole in the board (on the right of the original 2 holes)
Looks like it keyholed to me.
http://i210.photobucket.com/albums/bb201/trixiebud/hudson010.jpg?t=1215200488
The 3rd round I tried was an M855 green tip. Once again, no deflection.
http://i210.photobucket.com/albums/bb201/trixiebud/hudson011.jpg?t=1215200790
This round also failed to penetrate the board or the paper target cleanly. Another apparent keyhole. (it's the biggest gash in the center of the image, to the right of the first two exit hole clusters)
http://i210.photobucket.com/albums/bb201/trixiebud/hudson012.jpg?t=1215200877
The last round I tried was a .45 ACP ranger round. It penetrated the glass and the paper target cleanly. You can actually see the bullet hole in the paper. It's the nice round hole dead center of the MOA grid. :D
None of the rifle rounds on paper showed up very well in the images. It was hard to tell what I was getting with the camera because it was so bright out there. But none of the paper looked pretty where the rifle bullets impacted. Sloppy nasty keyholes. But all rifle rounds seemed to pass through the backstop with no deflection.
http://i210.photobucket.com/albums/bb201/trixiebud/hudson014.jpg?t=1215201019
Hey way to go!
So there's no deflection with the Frangible? Just curious to know and not that I'm in a position of any sorts to be shooting through automotive glass in a HRT or dangerous standoff, but what's the distance of your target from said glass? :cool:
I'd GUESS the target is at least 2 feet behind the glass, but not more than 3 feet. I tried to simulate a head sized target at the average distance behind a windshield.
This glass wasn't angled very much.. maybe only 20 degrees off of vertical so It would stand up while being shot.
Unfortunately I didn't have any of the Federal Bonded ammo that I wanted to test.
I'm wondering if one would put a dummy in a automotive seat and the glass in front to simulate a vehicle and then take a shot to see the "end" result? Of course maybe the test "subjects" could be from a junk yard.
Was this tempered safety glass or laminated windshield glass?
Looks like fun!
Was this tempered safety glass or laminated windshield glass?
Looks like fun!
I think laminated. Tempered would break into a bunch of tiny pieces wouldn't it?
It had no curve to it like a regular automobile windshield. It's almost like it was off of a bus or something with a flat piece of glass.
I have a profile shot of the glass that I can post later. It looked like two 1/8" pieces sandwiched together.
Yea, that was laminated glass. Did you have the glass positioned straight up and down, or was it leaning at an angle like most car windsheilds? I have wanted to do some testing like that for a while, just for shits & giggles. I thought about calling some of the autoglass replacement companies and getting a few windshields to use. I imagine the angle at which the bullet hits the glass plays a big factor in deflection.
I have also wanted to make up some mock walls of sheetrock, insulation & other materials to see how well what rounds penetrate.
Good job, and nice write up.
At a sniper match we hosted a few years ago, we set-up a stage where shooters would engage the driver of a vehicle from 80 yards, shooting the driver through the windshield of a motor vehicle from a second-story elevated position.
We obtained several dozen curved laminate automobile windshields, set them at angles typically found on automobiles, and positioned an IDPA target (for scoring purposes) behind the windshields at a distance representative of a driver seated in a vehicle. Each shooter (25 civilian, LE and military) fired 5 rounds at the driver for an attempted head shot with the ammo they brought for the day. No one knew beforehand what each stage would entail and each shooter started with a fresh windshield. Various configurations of ammo used that day included 5.56mm and 7.62mm match, ball, HP and TAP; mostly factory ammo, but some handloads. 5 range officers shot the course of fire beforehand; I used Hornady 5.56mm, 60 grain TAP Barrier rounds in a bolt gun with 24" barrel.
All rounds deflected, some more than others. We found that 5.56mm broke-up and deflected the most. But even 7.62mm couldn't be counted on to strike the target to point of aim. The same rounds from the same weapon wouldn't strike at the same point with any degree of certainty. Overall, 7.62mm was the better performer due to bullet mass, but bullet deflection was still a problem regardless of caliber. Many rounds missed the intended point of aim by several inches and some missed the head completely. This being the rule rather than the exception.
The conclusion from this stage is that neither 5.56mm or 7.62mm rounds can be fired at actual curved laminated windshields and be expected to strike the point of aim on target with any degree of certainty or expectation to end a conflict with only 1 shot. Nor can you predict with any degree of certainty the direction or amount of deflection. This is just one set of known variables and the results from that exercise.
I imagine the angle at which the bullet hits the glass plays a big factor in deflection.
Could be. My piece of glass was set about 20 degrees off of vertical. This was so I wouldn't bust it up if it fell over after each shot.
My lack of deflection goes against what MX5 has seen. So it might be because I was shooting almost straight into the glass. I put the paper targets on the wood for the specific reason of documenting the location of the bullet impact. Like I said, I just happened upon the glass so I wasn't set up for an ideal test.
Composition of the laminate, curvature of windshield and angle to the target will all have significant effects. The results from our exercise is only one possible outcome based on the set-up we employed. Ours was a shooting challenge based on one possible scenario that could be encountered. I've found that results on target are much more predictable if the shooter is standing on the same surface that the vehicle is on and shooting into the vehicle through the windshield at a relatively close distance. The shooter and target are on the same relative plane with the glass curvature becoming the primary factor. Ricochet, bullet fragmentation, glass splinters and glass powder are to be expected.
At a sniper match we hosted a few years ago,. . .I used Hornady 5.56mm, 60 grain TAP Barrier rounds in a bolt gun with 24' barrel.
"24" feet/foot barrel? Wonder how one would be able to maneuver such a rifle?
Anyways, we know what you mean. :p Very informative experience you've related. :cool:
MX5's comments are right on. Angle and composition of glass is a critical factor, as is distance the target is away from the glass. In this type of testing, it is important to calculate not only the degree of deflection, but also capture the wound track of the projectile to determine how badly the terminal performance was degraded.
MX5's comments are right on. Angle and composition of glass is a critical factor, as is distance the target is away from the glass. In this type of testing, it is important to calculate not only the degree of deflection, but also capture the wound track of the projectile to determine how badly the terminal performance was degraded.
For sure! This was just Hill Billy researsh though. Indeed the glass was not angled enough to typify a passenger car windshield. And I have no idea of the composition of the stuff.
I honestly hoped my beloved M193 would make it cleanly through the glass, although previous L.E. accounts had me doubtful. :p
The real reason for the test was just to see if the frangible would retain any mass after the glass. The other rounds were fired just cuz I had them.. and the glass in front of me.
For sure! This was just Hill Billy researsh though. Indeed the glass was not angled enough to typify a passenger car windshield. And I have no idea of the composition of the stuff.
I honestly hoped my beloved M193 would make it cleanly through the glass, although previous L.E. accounts had me doubtful. :p
The real reason for the test was just to see if the frangible would retain any mass after the glass. The other rounds were fired just cuz I had them.. and the glass in front of me.
If you MUST bust glass, Federal Tactical Bonded 62gr is about the only way to go other than Corbon DPX. I prefer the Federal load though because the soft nose will contour to the glass and there will be less deflection, also, there are no "petals" to break off and you get a better mushroom, albeit less penetration (still over 12" in gel after the windshield).
The best LE .223 loads for intermediate barrier penetration are the 62 gr Federal bonded JSP Tactical (LE223T3) and the similarly performing 55 gr Federal bonded JSP load. The Swift 75 gr Scirocco bonded PT and 60 gr Nosler Partition JSP bullets are also good choices. The all copper Barnes TSX bullets can work reasonably well, although the expanded "petals" shear off sometimes when penetrating glass intermediate barriers. None of the OTM bullets, even the heavy 75 - 100 gr loads, offer acceptable performance through automobile windshield glass. FWIW, contrary to what many believe, 62 gr M855 FMJ also is not very good against glass. For military use, the M995 AP is the best choice for vehicles and glass.
FWIW, contrary to what many believe, 62 gr M855 FMJ also is not very good against glass.
I would echo that for sure just based on what I shot above. I've read in the gun rags where it'll say something like... "the author carries M855 in magazine "X" incase he needs to get better penetration through auto glass"
PRGGodfather
07-13-08, 01:11
The best LE .223 loads for intermediate barrier penetration are the 62 gr Federal bonded JSP Tactical (LE223T3) and the similarly performing 55 gr Federal bonded JSP load.
Dr. Roberts is spot on as usual, since he IS one of the foremost authorities on ammunition ballistic testing and is intimately familiar with the FBI Protocols using 10% ballistic gelatin.
I have had the privilege of participating in about six ballistic workshops by Winchester, Hornady and ATK (Federal) in the last 4-5 years, and in all of the workshops attended, we tested a variety of .223/5.56 configurations on auto windshield glass.
Each time, the laminated windshield glass was placed in a frame that held it canted up and down (about 45 degrees) and left to right (about 45 degrees). A block of ballistic gelatin was placed behind it no more than 18" to simulate a suspect driver.
In many cases, significant deflection was noted, yet other times, there was no deflection. Based on this limited experience, I would suggest that bullet deflection after passing through glass is VERY unpredictable.
In virtually all of the cases, the terminal ballistic performance of the .223/5.56 was significantly reduced, because so much energy was used to penetrate the glass. There really was not much energy left behind. While some of the rounds penetrated the gelatin as much as 11 inches or so, penetration after laminated glass was 30-40% less than the documented penetration on bare or clothed gelatin.
Having attempted getting a bullet through different types of glass -- the best thing I have read about this was,
"We should remember that glass is made of sand. Depending on impact velocities, sand stops many rifle bullets very effectively."
In a sense, such results should not be a big surprise, inasmuch the .223 just is not that heavy to start.
Given some of the inherent capabilities (or lack thereof) of this patrol rifle caliber, the only appropriate response to a motorized threat heading towards you (provided an escape route does not exist) is continued follow-up shots to the suspect driver until at least one good round gets through without interference.
Be safe, have fun and shoot straight!
Alan
continued follow-up shots to the suspect driver until at least one good round gets through without interference.
Definitely!
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