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Is it possible to ruin a Bullet's BC?

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Is it possible to ruin a Bullet's BC?

Old 06-27-2006, 05:03 PM
  #1  
Nontypical Buck
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Default Is it possible to ruin a Bullet's BC?

Redclub wrote the following:

My Elk load last year was 115 grains of T7 wonder wad and a 348 powerbelt. Out of an Omega this was dead on at 118 yards,and 6" low at
160 yards and 20" low at 200 yards,I shot this load a lot to verify these drops.
I appreciate Red Club's comments for a couple of reasons. Primarily because he tested his load through a considerable range and KNEW where his rifle was shooting through the range. Had he used a ballistics calculator to "predict" where he'd be at the different ranges, he'd been way, way off. Also because it may shed some light on what may happen to a pure lead projectile when we push them hard.

Below I attached a trajectory which has a MV I would anticipate with the load and closely matches his results in the field. To approach his field performance, I had to reduce the B.C. of the 348 powerbelt considerably. Notice thatI used .10 for the BC. Ballistics published at the Powerbelt website http://powerbeltbullets.com/docs/PBB_Ballistic_Chart.pdfsuggest a B.C. of .206 at sea level. Notice also that their ballistics chart indicates 31% greater energy at 150 yards thanthe chart below. Also note that Redclubsenergy is 38% greater at the muzzle than 100 grains of pyrodex pellets.

I was very surprised to see Redclub's drop at 150 yards with a 118 yard zero. I think it possible, that 115 grains of 777 is flattening the front of the 348 PB's andruining the Ballistics Coefficient of the Bullet. When you think of it. One is accelerating the bullet to aMV in a time and distance span approximately equal to the span a Bullet is "decelerated in a game target" We know what kind of deformation takes place in an animal. It would be interesting to know howcharges deform the nose of the bullet into relatively differing ballistics coefficients. It may actually be possible for Redclub to reduce his charge and deliver more energy downrange.

Happy Hunting, Phil
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Old 06-27-2006, 05:05 PM
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Default RE: Is it possible to ruin a Bullet's BC?

I guess the attachment didn't work. I'll try again.

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Old 06-28-2006, 07:57 AM
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Default RE: Is it possible to ruin a Bullet's BC?

Well, I don't know if you could completely RUIN the B.C. of a bullet, but you can certainly damage it, and it doesn't take much of a change in the projectile's configuration, or even the slickness of the exterior surface, to reduce the B.C. noticeably.

In addition, some manufacturers have a tendency to claim higher ballisctic coefficients than their projectiles seem to have, when you test them (many are "calculated" based on shape,rather than determined empirically on an instrumented test range.....)
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Old 06-28-2006, 08:12 AM
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Nontypical Buck
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Default RE: Is it possible to ruin a Bullet's BC?

ORIGINAL: eldeguello
In addition, some manufacturers have a tendency to claim higher ballisctic coefficients than their projectiles seem to have, when you test them (many are "calculated" based on shape,rather than determined empirically on an instrumented test range.....)
Yes, which is why one shouldn'trely on published B.C. either for determining trajectory or energy at range. I'm notsaying that the BC with charge is .10, only that this B.C. approximates the trajectory curve Redclub experienced in the field. Thanks to Redclub for sharing data he has a considerable investment in gathering.

I wish I had two chronys.This interests me considerably.

Happy Hunting, Phil
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Old 06-28-2006, 09:20 AM
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Default RE: Is it possible to ruin a Bullet's BC?

At present. Iforget which forum I read it on, but they were discussing bullet BC's and SD's. It was discussed how (as eledguello pointed out) many manufacturers over state the BC's of a projectile. This might be a marketing ploy I would guess.

I would also think something as simple as the deformation of the nose of the projectile would also effect the BC of THAT bullet in its flight path. Which is why many projectile makers suggest a special loading jag to limit the amount of damage to the projectile while loading.

In Pglasgow's concern, I think I too have observed in many of the ballistic coefficient calculators, that the numbers the manufacturer provide are not in correlation to the findings in the field. It is for that very reason, many of us on these boards continually stress the importance of not relying on the black and white print out from the charts, but instead put in the range time and learn what the projectile will do in your rifle.

How many have noticed that a certain rifle in their collection does not shoot according to the charts? Also, how many have witnessedwhat one rifle does with a load and projectile is not duplicated by a secondrifle with an identical charge.

I do find the BC calculators very interesting and they do give one an idea of what the certain load will do or how it may perform. But I never hang my hat on those charts.
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Old 06-28-2006, 09:55 AM
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Default RE: Is it possible to ruin a Bullet's BC?

ORIGINAL: cayugad
I do find the BC calculators very interesting and they do give one an idea of what the certain load will do or how it may perform. But I never hang my hat on those charts.
I think it worth noting, that the charts can only be as good at the data which goes into their calculation. The trajectory chart is not a precise predictor unless all the data going into the calculationclosely approximates reality. Alot of factors affect the performance of a particular load and it is only the performance which matters. The performance is "real life".

What was neat about Redclub's data is that it allows us to do the opposite of what cayugad and myself have warned about. Instead of attempting to "predict" a real life experience, it gives us the opportunity to take a real life experience and then to analyze it for additional information.

Happy Hunting, Phil
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