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**HELP** Need to understand trajectory(heavy VS light) in bullets.

 
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  #1  
Old 12-12-2010, 09:20 AM
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**HELP** Need to understand trajectory(heavy VS light) in bullets.

Here's my question Guys in same bullets(accubond/accubond, VLD/VLD etc.) with one at 130grn and the other at 140-150 which bullet would shoot the flatest at longer ranges(300-700yrds etc)? I've always thought the heavier bullet would have the better trajectory at longer distance being the lighter would run out of steam. EXAMPLE as I look at same bullet trajectories here at federals website the heavier bullet is the one that drops the most. I thought different at LONGER range.

Federal Premium - Rifle Ballistics

Explain to me why do we use the heavier bullets as opposed to the lighter for long range. In ending I do understand wind drift in the lighter VS heavier, but trying to understand what's stated up top thanks!
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Old 12-12-2010, 10:17 AM
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Re: **HELP** Need to understand trajectory(heavy VS light) in bullets.

The devil is almost always in the details.

Generally speaking:
Extremely light bullets start out very fast, then lose energy & speed, after which point they are a slow light bullet. Heavier bullets start out slower but with much more energy due to the added mass, which keeps the bullet from slowing down as fast as a very light bullet would (assuming similar shape). Also, the heavier bullet is apt to be more aerodynamic, which further helps the heavier bullet maintain energy & speed.

At EXTREME ranges you will see (in most cases) a point where the very light bullet will suddenly drop fast because of the lost speed & you will see where the heavy bullet suddenly is above the light on drop charts. If you never get to these ranges, you will not see this effect!

For hunting applications, residual energy, the energy at point of impact, is critical to determining how much damage a bullet is apt to do to an animal. For this reason many long range hunters prefer a heavier bullet for long-range big game hunting. For short to medium ranges a lighter bullet is often the better choice because of the flatter trajectory and reduced recoil, which leads to more accurate hits as ranging is less critical.

Remember, the devil is in the details. Look at the drop charts & residual energy for the loads you are considering & determine which is most advantageous WHERE YOU WILL BE SHOOTING. There is no universally "perfect" loading. If there were only one cartridge & loading would be in universal use.
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Old 12-12-2010, 11:25 AM
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Re: **HELP** Need to understand trajectory(heavy VS light) in bullets.

I'm no physics expert, but I think weight has something to do with mass in motion, yada yada Perhaps someone can explain the physics of all that... and, mass x velocity = energy which combined with expansion characteristics and bullet placement relate to terminal ballistics and lethality. ...and, then you get vastly different approaches such as the Berger vs Barnes debate.

None of which really has to do with flat shooting. Trajectory is mostly a function of muzzle velocity and BC.

In any case you have to keep in mind that for a given diameter bullet to be heavier, it either has to be (a) longer, (b) different shape ogive/tail, and/or (c) different materials.

Since you indicated "same bullets", I assume you really mean same materials/density. So, the shape/length changed affecting the BC with heavier (meaning longer) bullets often being of a higher BC although, you sometimes get longer/heavy/round nose bullets which are lower BC.

Also, you want to keep in mind that boat tails, etc have varying effectiveness at different velocities i.e. sub/super-sonic. Hence, some would say that an accurate trajectory curve would be characterized by multiple BCs.

We usually think of boat tails for long range and associate high velocity with boat tail/VLD. But, I think I read somewhere that boat tails aren't really helping above around 2000fps (or somewhere thereabouts). Hence, flat base bullets are preferred by benchrest shooters out to 200 yds. And, boat tails/VLD shine at longer ranges after their velocity has dropped somewhat.

I guess that's where the expression came from where people talk about VLDs "going to sleep" after about 200 yds.

...just my thoughts. I'd be keen to here from the experts.

thanks!
Richard
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Old 12-12-2010, 11:30 AM
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Re: **HELP** Need to understand trajectory(heavy VS light) in bullets.

I read about a guy shoot a long-ish (1900 yards !) shot with a 300 Ultramag using 210-grain VLD's... I wonder with a 150-grain, even a good-one if it would even remain supersonic at that range.
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Old 12-12-2010, 11:37 AM
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Re: **HELP** Need to understand trajectory(heavy VS light) in bullets.

Also, I beleive most of the external ballistics programs ask for the name/type/weight of the bullet. But, other than the environmental conditions the trajectory curve comes down to velocity and BC.

..where BC comes down to the shape of the bullet.

Also, Newton figured out that 2 objects of radically different weight fall at the same 9.80 meters per second squared.

Regardless of how far or fast two bullets travel, if they are fired at the same time with the muzzles parallel to the ground, the bulltes will hit the ground at the same time.

Therefore, weight doesn't do anything for/to trajectory except as to change the shape of the projectile and the shape has everything to do with BC and trajectory.

Again, that's just my understanding as layman.

thanks
Richard
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Old 12-12-2010, 11:42 AM
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Re: **HELP** Need to understand trajectory(heavy VS light) in bullets.

Well, you probably won't have anyone designing a lightweight bullet for extreme distance shooting because you get into other factors such as the internal ballistics associated with buring powder and launching the bullet and the retained energy at impact. etc...

But, I suppose it could be done on paper.
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Old 12-12-2010, 12:20 PM
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Re: **HELP** Need to understand trajectory(heavy VS light) in bullets.

Now about that idea of a bullet going to sleep, I am still on the fence about that one. But if you have the book called "precision shooting at 1000 yards", on page 224 he mentions the idea of a bullet going to sleep and says its hogwash and it always makes him laugh when someone mentions that. Also somewhere I saw, it might have been on the military channel, a sniper talking about how the bullet spin pulls a bullet back down towards earth. So there we involve the rate of twist in the barrel. So say if a barrel has a clockwise twist and that clockwise spin is truely causing the bullet to come back down or loss elevation, then why have barrel manufactures not experimented with a counter clockwise barrel twist??? I am no expert here but on my tv show I play one "ha ha ha"" but to me in some twisted sort of way it kinda makes sense. I hope someone with more experience will chime in here. Now I am going to have a headache just thinking about it.
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