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Old January 25, 2013, 01:08 PM   #1
tpcollins
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Ballistically speaking . . . what's more accurate?

If we take for instance .45 caliber 200 grain bullets, with jacketed lead being the shortest due to density, versus an all copper bullet being a bit longer, and an all brass bullet being the longest - which of the 3 would shoot the best 100 yard accuracy? Thanks.
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Old January 25, 2013, 01:56 PM   #2
Jimro
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I can't answer that question in reality because there are too many variables.

I can answer hypothetically if we make some assumptions. Assumption 1: that all bullets of the same type are mathematically identical in shape and density. Assumption 2: that all bullets have perfect balance. Assumption 3: that bullet length alone determines ballistic coefficient in this case.

With these assumptions (that cannot be replicated in reality) then the longest bullet with the highest BC will be the "most accurate."

This is only because the effects of wind will be smaller due to more retained velocity.

In reality, there is no such thing as a perfectly balanced bullet in a perfectly uniform lot so your best bet is to buy 100 of each and see how they perform in your firearm.

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Old January 25, 2013, 04:58 PM   #3
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Assuming all match grade quality I would give the nod to the longer brass bullet but for all practical purposes at close range like 100 yards you will be hard put to find any of them inaccurate. It would be more telling if you tried them at 200 yards or more.
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Old January 25, 2013, 07:33 PM   #4
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"Ballistically speaking . . . what's more accurate? "

The ones that go into the tightest cluster. Other than that, none of us can tell you what your rig and loading skills can produce with anything.
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Old January 25, 2013, 07:50 PM   #5
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The first thing I thought of was which would have the best twist rate for it's length.
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Old January 26, 2013, 09:46 AM   #6
tpcollins
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Thanks for the replies. Here is a pic comparing Hormady XTP versus the all copper Barnes TAC-XP. On each end is a jacketed lead 155gr XTP. left to right in the middle are the 125gr, 140gr, & 155gr Barnes TAC-XP. I have some Barnes samples in the 140gr and 155gr on the way - we'll see what groups the best.

When I plug my data into the Miller stability chart, the 155gr Barnes seems the best bet for my application.



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Old January 26, 2013, 10:07 AM   #7
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Wncchester had the best reply. If you want to get technical, the longer a bullet is, the greater the length of the lever arm by which aerodynamic forces try to turn the direction of the bullet off its trajectory and make it tumble. In general, length is the most critical factor. Sectional density of the bullet is the second most critical factor, as putting more mass into the spin and more inertia into plowing into the atmosphere makes the bullet harder to turn. However, mass does not trump length. A bullet that's twice as heavy and long and has twice the sectional density, will be harder to stabilize than its half-length lighter counterpart because length trumps weight in importance to stability.

That said, .45 handguns have more twist than is required for long range stability. So the chances are your whole selection will shoot. That's why it comes back to what Wncchester said.

There is a free stability estimator if you scroll down to the bottom of this page. It requires bullet weight, length, rate of rifling twist in your barrel, muzzle velocity, and atmospheric conditions to figure air density from. However, it will likely just give you very high stability factor numbers for all the bullets you have, so you once again get back to having to try them to see what seems to work best from your gun.
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Old January 26, 2013, 11:36 AM   #8
tpcollins
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Thanks again for the advise. Actually - I'm wanting to use these bullets in plastic sabots to shoot in a youth sized .50 caliber muzzleloader for my very young grandson. My goal is to find something that will shoot good at 50 yards with a light recoil as to not frighten the youngster.

I do have some really short 135gr XTP 10mm but they look more like a patched ball.
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Old January 26, 2013, 06:23 PM   #9
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Follow the link to that calculator. You will need to know your twist rate. You then have to assume the bullet spins up at that rate and that it doesn't slip inside the sabot. I don't know how you can be certain of that without trying, though.
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