Ballistic Glass

Uncle pointed out a few days ago that ballistic glass could be penetrated by a 12 gauge shotgun slug.  Alcibiades pointed out in the comments this site.   But holy polycarbonate penetration batman, do you see what a 45-70 government round does to it?  I remember a few years ago the antis pointed out that a .50 BMG could penetrate bullet proof glass, and showed it easily stopping an AK-47 round.  Interesting that one of the oldest metallic cartrdge loads is capable of doing the same thing.  It seems for penetrating ballistic glass, the best option is to be heavy.  I guess this comes back to what Joe Huffman said about momentum mattering more than energy.

4 Responses to “Ballistic Glass”

  1. Alcibiades McZombie says:

    Someone needs to hold a “Pierce-a-thon” in which ballistic materials are put to the test against an odd assortment of guns.

    (I suppose we could just ask scientists and engineers, but it’s clear that reporters don’t always listen to them. Thus, the need for the pierce-a-thon.)

  2. Nylarthotep says:

    Momentum matters more than energy? Sorry, I really need that explained. From a purely Physics point of veiw that is parsing things oddly.

    Does this contention refer to” high energy, low mass” projectiles typically having a lower penetration ability than a large mass projectiles with equivalent energy?

    Wouldn’t this contention be dependent on the ability of the projectile to maintain its integrity? A .50 caliber round has less penetration than a 9mm round in water, but has a much higher penetration in higher density material.

    Merely saying momentum matters more than energy is a bit simplistic, but with respect to polycarbonate it is accurate.

    I would like to see a discussion on this. It would also be interesting to hear discussions on ballistics also. I’ve got books on the topics, but it’s more fun discussing.

  3. NMM1AFan says:

    Great, now I have to buy a Sharps before someone tries to ban them.

    This is getting expensive.


  4. alex. says:

    Sharps? Nah. Nice gun, but for serious purposes get a Marlin Guide Gun. I’ve shot one quite a bit and it is a hell of a gun. Short, fairly light, and deadly. With 405 grain lead “cowboy shooting” loads it walks through just about anything. In one impromptu test it out-penetrated a .375 H&H with 300 grain solids (it’s great having friends with eclectic gun collections!). That was shooting through stacks of dry periodicals and through logs.

    This is nothing new, however. Back in 1955 Elmer Keith praised the penetration of the venerable .45/70 in his epic book Sixguns by Keith. On page 284 of my Wolfe Publishing reprint he talks of testing “imitation bear muscle” with various cartridges. The only one that went through 4 blocks of the stuff was the .45/70.

    Of course, bullet selection is paramount. The 300 grain hollowpoints should penetrate less. The 350 grain +P soft points by cor-bon and pmc, on the other hand, hit hard on both ends.