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Thread: Bullet disintegration?

  1. #1
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    Default Bullet disintegration?

    Ok, first the setup. I have been picking up the components I will need to reload for my AR-15 (if it EVER gets here) and somehow I ended up with a box of Barnes .224 Varmint Grenade 36 gr HP bullets. I know I bought them at Boondocks but I'll be danged if I know why I picked up 36 gr bullets.

    I have been reading books, internet articles and individual posts on several shooting forums for at least 6 months now and during that time I've found several differing opinions about everything to do with reloading including which bullets are suitable for a barrel twist rate. The first thing I discovered is, just like many other times in life, everyone has an opinion and none of them are the same. If I am to believe everything I've read, this is what I've found out.

    a)The 36 grain bullet will either do just fine and is accurate as can be or,
    b) It it will disintegrate into dust by the time it's traveled 30 inches downrange.


    So, since I know you guys are more experienced and infinitely highly qualified on this subject than anyone else on the internet, I'm going to ask if anyone has fired these bullets through an AR with the same twist rate and if so, what were the results? Can these be fired through a 1:9 barrel and if so, is there a specific powder/charge range to avoid/recommend for this bullet?

    Second question that I just remembered. I have a bunch of Lake City .223 once fired cases. Is this the "military" brass they talk about that has the thicker cases? If so, do I need to keep the powder charges lower because of pressure issues?

    Sorry for the questions. I'm learning but it's going to take a while to catch up with the rest of you.

    Have I mentioned yet that my rifle is taking way to long to get here?

    .

  2. #2

    Default Try'em

    The Barnes varmint Grenades are a solid copper and as such are longer than a standard lead core type projectile. The stability will be determined by the rifleing of your firearm and initial velocity at which it is launched.
    The velocities developed by a 223 shouldn't damage the bullet. However the impact at velocity deffinately will.
    Enjoy that's half of the sport.
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  3. #3
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    Default lake city brass

    Yes, it's mil brass.

    Recommended to reduce powder by 10%. Never worked with mil brass so that's all I can say about it.

    itty bitty boolets..... load 'em up and shoot 'em. Just don't plan on recovering anything you hit with them but I agree that's the fun of that game.....

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    Default Twist rate? Greenhill

    Do a net search for the "Greenhill Formula - Ballistics"

    This is one of the first locations yielded:

    http://www.ebr-inc.net/articles_Greenhill_Formula.html
    or if the link does not work, paste this into your web browser
    ebr-inc.net/articles_Greenhill_Formula.html

    Ballisticians use the Greenhill Formula to determine the spin rate required to stabilize a bullet in flight so the flight path will be consistent, bullet to bullet which, of course, makes for tight groups. Greenhill dates back to when they first started putting rifling in barrels. There may be better formulas or models for supersonic and smaller bullets, but as I am not a ballistician, I have not put the effort into researching them.

    Bullets benefit by the gyroscopic stability given by rotation. The faster the bullet travels, the faster the spin and the tighter the twist rate, the faster the spin. Calculating the appropriate spin rate for a bullet of a given density and dimensions and velocity is often described as part science and part art. Basically it is physics, but the math is complex, so it looks like a black art. Nonsense. It is physics.

    But there are complications. If a bullet is very fragile, and spinning very fast, it may break up in flight from the centrifugal forces alone. This is also plain physics plus some materials science, but if your ballistics requires a faster spin rate (to stabilize your bullets' flight) than your bullets' strength can stand, you are in an untenable situation. You either accept a spin rate that is not enough to stabilize your bullets and they tumble in flight or you spin the bullet fast enough to stabilize the flight path, but tears the fragile bullet apart with cetrifugal force.

    Most bullets have a speed/spin performance envelope where they perform well. If they didn't, they would not sell many bullets.

    Good Luck

    Lost Sheep.

    Remember, only believe half of what you see and one quarter of what you hear. That goes double for what you get from the internet. Even this post. Maybe especially this post.

    Do your own independent, confirming research when ANYONE gives you new facts on the web.

    Also remember, even the idiotic stuff might have a kernel of truth buried in there somewhere.

    Lost Sheep

    disclaimer: I do not know you, so if my advice seems over-obvious or simplistic, take into account my ignorance of your experience level. Also, other readers of all experience levels are reading.

  5. #5
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    Default

    Quote Originally Posted by Lost Sheep View Post
    ... Remember, only believe half of what you see and one quarter of what you hear. That goes double for what you get from the internet. Even this post. Maybe especially this post.

    Do your own independent, confirming research when ANYONE gives you new facts on the web.
    I have some data in the Barnes book for this bullet. The only difference is that I think they used a different twist rate. 1:12 maybe, but I don't know for sure until I go pull out the book.

    I guess I'll load some up and, when I get to the range, fire one off and then look at the target. If it has the appearance of being hit with a load of 71/2 birdshot I'll have my answer.

    Of course, all of this depends on WHENEVER ROCK RIVER DECIDES TO SHIP MY %@&$ RIFLE!

    Thanks for the answers guys.

  6. #6

    Default

    I have shot ground squirrels with the 50 gr version of the Barnes Varmint Grenade. Used a Cooper Model 21 with 1 in 12 twist (don't quote me on the twist rate - it may be 1 in 14).

    The bullets performed exactly as advertised. They are a sintered material if I understand correctly, and are designed to fragment upon impact. They do.

    As a matter of curiosity, I have calculated twist rates and velocities for .223 loads. About 180000 rpm or just a little more is the number that comes up over and over.

    You have the combination of a light bullet, and high twist rate which will have it spinning faster. I don't know if, in your case, they will fragment in flight due to excessive centrifugal forces. Unless you find someone who has tried it, you will just be getting opinions. For all we know, the sintered bullet may hold together better than a jacketed bullet as far as centrifugal forces go.

    Why don't you call Barnes and ask?

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    Default

    Quote Originally Posted by Nutjob View Post

    Why don't you call Barnes and ask?

    Excellent idea! I don't know why I forgot about that option. Maybe they have tried firing these through a barrel with 1:9 twist. I was hoping though that someone here had tried it but hey, maybe I'll be the one to give it a "shot", so to speak.

  8. #8

    Default O.K - fine

    Bookseller,

    I got this info from Barnes:

    the 36gr. and 52gr. Varmint Grenade bullets have a copper/tin core in a guilding metal jacket and are designed to hold together at high level velocities and the latest (2009) lots are designed to be used in firearms of 1-10 twist or faster with no problems. Hope this helps.

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    Default

    Quote Originally Posted by mauserboy View Post
    Bookseller,

    I got this info from Barnes:

    the 36gr. and 52gr. Varmint Grenade bullets have a copper/tin core in a guilding metal jacket and are designed to hold together at high level velocities and the latest (2009) lots are designed to be used in firearms of 1-10 twist or faster with no problems. Hope this helps.

    Wow, thank you sir. I appreciate all the info from you guys. Hopefully, I'll be able to post some answers to others here once I gain a little more experience.

  10. #10
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    Default

    Quote Originally Posted by Bookseller View Post
    a)The 36 grain bullet will either do just fine and is accurate as can be or,
    b) It it will disintegrate into dust by the time it's traveled 30 inches downrange.
    The Barnes VG is not a solid copper bullet. It is a thin jacketed hollow point with highly fragmentable core material. It will not fly apart on it's way to your target. I have shot it as high as 4300 FPS in my .204

    In the .204 it is a 26gr bullet. I was very disappointed in accuracy during load development in my rifle. I tried two powders and several charges with speeds ranging from 3780 to 4300fps. I tried several seating depths in a .090 range from my best results with other bullet types.

    I ended shooting over 150 bullets in the grenade and finally gave up. My rifle likes 32 and 39gr Blitz Kings, 40gr A-Max's and 30 and 35gr Berger's just fine. It would not produce good results with the Varmint Grenade in my testing.

    I realize that you are loading for a .223 and your bullet selection will be a bit heavier in the grenade. I hope it works out for you. If not give Blitz Kings a try, they are incredible it my rifle.

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    Default

    Thanks for the info Marshall. Once I finally receive my AR I'll resurrect this thread and post the results. At least it should be fun trying to find out what my rifle will like by trying all sorts of differing loads.

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