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Old January 23, 2013, 11:01 AM   #1
tpcollins
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Lead versus all copper accuracy

Probably posting in the wrong sub-forum but I'm looking for some technical knowledge. I want to come up with a light recoil bullet/sabot load for my grandson in the muzzleloader I just bought him. The Hornady 10mm XTP in 155 grains is .555" long. The same 155 grain Barnes all copper TAC-XP is .732" long. The longer Barnes will facilitate loading easier since it will stick out of the sabot more.

But will the longer Barnes all copper bullet accuracy be less, more, or about the same as the shorter lead XTP bullets? I would think the longer Barnes would "tumble" less. Thanks.
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Old January 23, 2013, 11:05 AM   #2
Jimro
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I would expect a normal variation between those two bullets, some rifles preferring one or the other.

In theory the monolithic construction should be better from a bullet balance point of view. In practice I wouldn't bet on it.

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Old January 23, 2013, 11:12 AM   #3
Unclenick
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Tpcollins,

You have it backwards. Greater length gives air pressure a longer lever arm with which to try to turn the bullet and make it tumble. For a given rifling twist rate, length is the single most influential factor on bullet stability. Weight comes second, and is only able to predict stability among bullets of similar construction because it then tends to predict length for a given weight. Muzzle velocity is the least significant influence.

Bottom line, whether or not you can get that Barnes to stabilize will depend mainly on your rifling twist rate, and to a lower extent on your muzzle velocity. There is a stability estimating calculator on this site if you scroll down to the bottom of the page.
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Old January 23, 2013, 12:45 PM   #4
tpcollins
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I have that stability formula saved. The Hornady 155gr .555" bullet has a SG factor of 3.100+, the 155gr Barnes TAC-XP .732" bullet comes in with a SG factor or 1.5-1.6 when plugging in a 1600-1880 velocity. I called Barnes and their sending me a few samples. I'll compare theory with reality later. Thanks.
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