Ballistics beyond 2000 yds : do we need/trust them?

[Michael Eichele]

Gustavo,

Keep up the good work. Someday, between all of us, one of us is bound to make a very usefull computer based shooting tool!

I am very sorry I have allowed myself to aid in the hijacking of your thread and entertain arguments. My apologies

I also apologize to Catshooter for "arguing" back and forth with you.

 

[Eaglet]

I think most people would agree that very rarely you can have two different loads with the same bullet, same MV's that the POI is the same and that they group the same.
That said, the external ballistics is showing me that something is different with the internal ballistics; then it just may be more than speculation the change in BC on the bullet from one load to the other. I would think this would even be more noticeable at long range. I'm just wondering!
I do agree and just makes a lot of sence to me what GG said:

[ QUOTE ]
Also, your bc will change throughout the barrel's life whether it be custom of factory. This is a major fault for range dials and reticles that have been calibrated for a certain bc.

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[Gustavo]

[ QUOTE ]
Gustavo,

Keep up the good work. Someday, between all of us, one of us is bound to make a very usefull computer based shooting tool!

I am very sorry I have allowed myself to aid in the hijacking of your thread and entertain arguments. My apologies

I also apologize to Catshooter for "arguing" back and forth with you.

[/ QUOTE ]

Michael, no need to apologize, your input is always welcomed!

Please try to keep the loop going.

 

[Michael Eichele]

Eaglet,

To go along with what GG said about the BC changing with the decay of barrel quality over time, you also add in ever changing components such as powder lot number and burn rate. Example, my 308 had an awesome load using the 155 AMAX and BENCHMARK powder. Velocity was 2850 (average). When that powder got used up, I bought more. I now shoot the same powder charge (because it is by far the most accurate) but the differance is I get only 2717 FPS on average now. 133 FPS differant. Trust me, the BC changes as well with that velocity change. Does it change enough for me to worry about at ranges I will be asking that load to perform at? No. If the velocity were much higher though and could utilize that load at say 1300+ yards, and had the same small change in BC, yeah, I would find out what it was exactly, plug that into my software, and hit my target with confidence.

Regards!

 

[Eaglet]

meichele,

Thank you, that makes sence to me!

 

[lerch]

[ QUOTE ]
Sure you can point out something you feel you need to. You just don't need to do it in bad tone. I think the two guys just misunderstood each other is all so no need to "DUHH" anyone, ever! . It's all about free communication but if some feel inhibited to speak for fear of being "duhhed" than people won't share anything at all

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EXACTLY!!!!!!!!!!!!!!!!!!!

 

[Coyboy]

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Sure you can point out something you feel you need to. You just don't need to do it in bad tone. I think the two guys just misunderstood each other is all so no need to "DUHH" anyone, ever! . It's all about free communication but if some feel inhibited to speak for fear of being "duhhed" than people won't share anything at all

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EXACTLY!!!!!!!!!!!!!!!!!!!

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X 3

 

[Coyboy]

Cat shooter,

Would it not be posible for the same bullet at the same velocity to have a different BC using different powder primer combinations?

I think it is possible, Red primer and red powder is a intesly hot burning combination and as it accelerates the Nosler partition down the barrel it erodes a couple of grains of the exposed lead away, from the rear of the bullet.

On the other hand purple primer and powder is a single based ball and does not erode any lead away. It creates the same velocity and pressure in the same barrel with the same bullet.

Yet the red primer powder altared the BC of the same bullet.

This is an example with a exposed lead base in the bullet. Though it may not exist in all bullets their is always the possibility that under the right conditions, that anything is possible.

So may-be this answered your question to Meichel. May-be it does not, either way it seems quite possible to me.

 

[CatShooter]

[ QUOTE ]
Cat shooter,

Would it not be posible for the same bullet at the same velocity to have a different BC using different powder primer combinations?

I think it is possible, Red primer and red powder is a intesly hot burning combination and as it accelerates the Nosler partition down the barrel it erodes a couple of grains of the exposed lead away, from the rear of the bullet.

On the other hand purple primer and powder is a single based ball and does not erode any lead away. It creates the same velocity and pressure in the same barrel with the same bullet.

Yet the red primer powder altared the BC of the same bullet.

This is an example with a exposed lead base in the bullet. Though it may not exist in all bullets their is always the possibility that under the right conditions, that anything is possible.

So may-be this answered your question to Meichel. May-be it does not, either way it seems quite possible to me.

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Hundreds of Thousands of military 30-06 FMJ, 7.62 NATO FMJ, and 5.56 NATO FMJ bullets have been recovered from test materials for study.

They all have exposed lead bases.

There has never been even a hint of melting. When retrieved, they show fresh tool marks.

Melting lead does not happen.

.

 

[Coyboy]

"Melting lead does not happen"

So why are gas checks put on solid lead rifle bullets?

 

[Coyboy]

Did you ever consider that the military loads use a cooler burning propelent to avoid excessive heat in their rappid fire barrels. Military lead alloy may also contain more tin thus making it withstand higher temps.

With your extensive background I would think you would consider all the variables.

 

[MagMan]

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"Melting lead does not happen"

So why are gas checks put on solid lead rifle bullets?

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If that were the case wouldn't they call them no-melt checks?

 

[Fiftydriver]

Catshooter,

Just wanted to add my 2 cents. No idea about lead melting in rifles but I know alot about the situation in big bore handguns.

Main reason for gas checks on lead bullets is to prevent leading by friction to the bore.

That said, on big bore revolvers with compensators such as the Ported Taurus and S&W handguns, lead forms on the ports of these handguns when using lead bullets. Not with gas checked bullets but it does with plain base lead bullets of even hard cast nature which says that there is some lead vapor coming off the base of these bullets to build up on the external surfaces of the porting.

Also, another handgun I am quite familiar with is the Magnum Research Desert Eagle. This is a big gas operated semi-auto handgun designed for the largest handgun magnum calibers of its time. You can get these chambered in 357 Mag, 41 Mag, 44 Mag and 50 Action Express.

In the owners manual it STRICTLY forbids the use of any bullet with exposed lead at the base of the bullet. This is because in less then a clip full of rounds with expose lead at the base, the lead vapor will build up in the delicate gas porting vents under the barrel and will turn the handgun into a $2K single shot!!! They are also unable to repair this because there is no way to get in and clean out the lead build up.

So, while I have no experience on rifles as far as testing this it does happen in big bore revolver and semi-auto handguns. If it happens with these applications I do not know why it would not in rifles but thats neither here nor there.

Just wanted to point out that in some applications, lead will melt off so some degree off the base of a bullet.

Back to the debate!! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

As far as BC changing, no comment, will sit this one out!!

Kirby Allen(50)

 

[CatShooter]

[ QUOTE ]
"Melting lead does not happen"

So why are gas checks put on solid lead rifle bullets?

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Because it was long ago discovered that the lead deposits on barrels came from "gas cutting" not lead melting. Lead melts at around 750 to 850 F, depending on the alloy.

If you ever shoot large old time cartridges like the 45-120 (I do), and use good lubes, you will find that even with naked lead, there is no leading "IF" the bullet is a few thou oversized.

But if the bullet is a few thou "undersized" then the first shot will start leading. If you ever shoot paper patched bullets, you will find the patches a few feet in front of the rifle, just slightly singed - the paper burns at 400+ F.

SO... if the leading does NOT happen with an oversized, but does happen with an undersized bullet, then it is obvious that it's gas cutting, and not melting that is the culprit.

.