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Thread: OK math wizzes

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    OK math wizzes

    If you have a plate of steel that you lay at a 45 degree angle and from the floor up it has to reach 10 ft, how long does the sheet of steel have to be. Same thing if you changed the angle to 30 degrees?

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    Hate Math! Should be 15 ft for the 45 degree angle yes?
    Last edited by Lunk1; 06-13-2014 at 08:10 PM.

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    simple geometry

    Asq + Bsq = Csq

    So if A = 10
    and B = 10

    Then C must equal (100 + 100)sq = 200sq = 14.14213562
    not 15 ya dummy!

    and I'll let you do the rest of your geometry homework
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    ^this is for the 45 degree

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    ^^^^… what Roman said, provided it is a right triangle.
    Last edited by almostgone; 06-13-2014 at 10:24 PM.
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    So none of you smartys know the length at 30 degrees?

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    Quote Originally Posted by Lunk1 View Post
    If you have a plate of steel that you lay at a 45 degree angle and from the floor up it has to reach 10 ft, how long does the sheet of steel have to be. Same thing if you changed the angle to 30 degrees?
    If I'm reading it right, 30° would give you a hypotenuse of 20 feet....less the thickness of the steel plate. Depends if your long side is overlapping your vertical or butting up to it. Before cutting steel, lay out a string template and see how it looks....string is cheap.
    Last edited by almostgone; 06-13-2014 at 10:27 PM.
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    Quote Originally Posted by almostgone View Post
    If I'm reading it right, 30° would give you a hypotenuse of 20 feet.
    Got any experience with AR 400 or Ar 500 steel at 45 degree against big bores?

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    Quote Originally Posted by kelkel View Post
    What's wrong with you people.
    Math on Friday night.....
    Friday night = another work night.
    There are 3 loves in my life: my wife, my English mastiffs, and my weightlifting....Man, my wife gets really pissed when I get the 3 confused...
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    Quote Originally Posted by Lunk1 View Post
    Got any experience with AR 400 or Ar 500 steel at 45 degree against big bores?
    Not really, Lunk but I would expect one hell of a skip/ricochet......range?
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    Quote Originally Posted by almostgone View Post
    Not really, Lunk but I would expect one hell of a skip/ricochet......range?
    10-4. 2ft of granulated rubber ahead of the steel

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    Quote Originally Posted by Lunk1 View Post
    10-4. 2ft of granulated rubber ahead of the steel
    Range= distance.

    The rubber should buffer it a good bit, but I'm unsure of safety...would suspect it makes a good trap.???
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    Quote Originally Posted by almostgone View Post
    Range= distance.

    The rubber should buffer it a good bit, but I'm unsure of safety...would suspect it makes a good trap.???
    Its used often but trying to price what a real cost is vs hiring big companies. 45 degrees is a minimum but the lower you go the stronger the steel gets essentially because the deflection angle is greater.

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    Im superman so I will just stretch or compress it to make it the same.

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    Quote Originally Posted by Lunk1 View Post
    Its used often but trying to price what a real cost is vs hiring big companies. 45 degrees is a minimum but the lower you go the stronger the steel gets essentially because the deflection angle is greater.
    Does a big company bear the brunt of the liability if someone got injured (hope of never happens) and the design was lacking??...or does range insurance CYA?
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    Quote Originally Posted by almostgone View Post
    Does a big company bear the brunt of the liability if someone got injured (hope of never happens) and the design was lacking??...or does range insurance CYA?
    I'm sure both would share responsibility but if there is a failure it would help to have somewhere to point a finger.

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    Quote Originally Posted by Lunk1 View Post
    I'm sure both would share responsibility but if there is a failure it would help to have somewhere to point a finger.
    That was my line of thinking but wasn't really sure about it. Hope.your project goes well...always good to hear positive news regarding firearms/ownership and responsibility.
    Last edited by almostgone; 06-13-2014 at 11:46 PM.
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    The steel sheet would have to be 20 ft at a 30° for a right triangle.

    Any time you're shooting steel targets there is an element of risk from the inherent nature of the activity. The way that you mitigate the risk to an acceptable level is to use well designed and constructed targets.

    First and foremost, if you're shooting rifle rounds, you need AR-500 steel. AR-500 is the minimum hardness needed to fragment bullets safely. Anything less than AR-500 will crater and pock and will eventually send jacket back at you. AR-500 steel should ideally be cut with a water jet or underwater plasma. A cutting touch will make the steel lose it's temper around the edges. I speak from experience when saying that these don't hold up well and will fragment when hit.

    How the steel is mounted is another major consideration. Ideally, the mounting systems should have some "give" in it. By allowing the target to move when struck, you can dissipate some of the bullets energy by converting it to movement. The problem is that as the plates gets bigger, for instance moving from an 8" to 12", it moves less and you get less benefit from the movement. Also, the mounting system should direct the bullet fragments in a safe direction, which is generally into the ground underneath the target. The accepted optimal angle for this seems to be 15 degrees.

    Finally, you need too consider the distance the target is placed. Steel is damaged by velocity. A good guideline is 3000 fps. If the bullet hits the target at greater than 3000 fps, you'll see accelerated wear. Thus, if you shoot a 55 grain .223 bullet from a 24" barrel and a 77 grain .223 round from a 14.5" barrel, they will damage the steel differently. The 24" barrel may require 125-150 yards to minimize damage to the steel while the 14.5" barrel may be good at 75 yards. If you're shooting less conventional calibers, like a 22-250, you may need several hundred yards to keep the steel happy.
    Last edited by numbere; 06-14-2014 at 03:51 PM.

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    All very good information. How would this all apply if using a granulated rubber trap ahead of the steel. Since the granulated rubber essentially stops/slows down the round similar to a dirt berm, would AR 500 still be necessary? We are talking at 25yrds by the way.

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