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CALIBER CHOICES

 
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  #15  
Old 06-13-2002, 08:36 AM
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Re: CALIBER CHOICES

Hello to all.

I wanted to get my 2 cents in here too.

JonA

On the ballistics you gave for the 180 gr (3450FPS) and the 240 (2950 fps)

Heres what my Oehler program with a graph printout shows.
Energy level at 100 yards (stating out)
180 gr---4223 FP
240 gr---4824 FP

At 1000 yards 180gr---1790 FPS---1281 FP
240 Gr--1764 FPS---1654 FP

At 1100 yards 180 Gr--1659 FPS--1100 FP
240 Gr--1665 FPS--1478 FP

At 1200 yards 180 gr--1536 FPS--944 FP
240 gr--1571 FPS--1316 FP
Clearly the 240 is the superior bullet as per energy and it catches the 180 at a tad less then 1100 yards.

As per the velocity in "longer" barrels.
I get 3150 FPS and 3200 FPS(50 degrees) with my Tomahawk and a 34" barrel and with the 240 gr bullet. I'm not sure if you were refering to 34" barrels when you mentioned "Longer Barrels".

Now program that speed against the 180 gr at 3450 and you will find that the 240 will catch the 180 at 500 yards.

If I were a short range hunter and hunted big game such as elk, I would want the superior bullet which is the 240 at ANY range I hunted. For smaller game like deer
the 180 would be fine.
For longrange and above 500 yards, I would use the 240 everytime. It's hard to match up a bullet with a BC of only .540 (180 Gr) to one that has a .711 BC (240)

Another interesting fact is, the time of flight in your scenerio is 1.2 Seconds at 1000 yards for either bullet and 1.5 Seconds for both too at 1200 yards.

I'll take the 240 any day, but then again, that's a longrange hunter's point of view.
Higher BC bullets will retain their velocity and energy level MUCH better then the lighter lower BC bullets will at almost any range.

The Tomahawk is an improved 300 RUM with a 35 degree shoulder that holds about 8 grs more powder.

Boyd has a 36" barreled 300 RUM that I am quite sure he will get 3100 FPS with the 240 gr.
He "won't" beat the Tomahawk even though I have 2" less barrel. [img]images/icons/grin.gif[/img]

Later
DC [img]images/icons/smile.gif[/img]

[ 06-13-2002: Message edited by: Darryl Cassel ]
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  #16  
Old 06-13-2002, 08:46 AM
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Re: CALIBER CHOICES

Jon A,

I'm not sure why they don't list this bullet on their site, but here is a link to it on Sinclair's:
http://www.sinclairintl.com/cgi-bin/...073&type=store

I think in their catalog it is listed as have about 0.508 BC

HTH,

Monte
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  #17  
Old 06-13-2002, 10:17 AM
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Re: CALIBER CHOICES

Wind drift as I understand it:

Time Of Flight (TOF) has a significant effect of wind drift.

Example:

1300fps, 155grain .30 cal .5BC bullet, 10mph full value wind, TOF to 500 yards 1.377sec, wind drift 36.2 inches.

2600fps, 155grain .30 cal .5BC bullet, 10mph full value wind, TOF to 500 yards .708sec, wind drift 20.6 inches.


another to be checked by anyone interested:

Two bullets of different caliber (significantly different) with identical BC's. shot to the same distance in identical wind, theoretical result should equal essentially the same wind drift (disregarding sail area).

When all else are equal weight has no effect on wind drift.
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  #18  
Old 06-13-2002, 03:48 PM
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Re: CALIBER CHOICES

A pilot told me that a 747 and a supercub will both drift ten miles off course in one hour in a ten mile per hour full value wind. How in hell does that relate to BC's and time of flight? If you guys can keep the answer in words of less than than five letters and numbers under 10 I would be appreciative. [img]images/icons/wink.gif[/img]
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  #19  
Old 06-13-2002, 09:59 PM
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Re: CALIBER CHOICES

Ian, your pilot friend was right, for as accurate as he could measure. Both planes take off into a sea of flowing air and are moved allog with it at the same speed as the wind. The difference is how quickly the planes "accelerate" from a laterial speed of zero up to match the 10 MPH cross wind. The lighter cub would actually get up to that wind speed quicker than the 747, but they will both eventually reach that speed and then follow parallel paths. The difference is in the acceleration sideways due to the wind. There will be a difference, but we are talking a few seconds compared to an hours flight time. The difference can't be measured by the pilot.

In our world of LRH the flight time is so short that we hit the target (hopefully [img]images/icons/smile.gif[/img] ) before the bullets are up to that speed. Therfore we see and measure the difference. We are just using a much finer measuring scale than your pilot friend.
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  #20  
Old 06-13-2002, 11:33 PM
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Re: CALIBER CHOICES

Exactly like RBrowning said. Don't think of a plane as something moving along with a crosswind flowing against it. Think about driving your car down a road...and the road is moving sideways as you drive!

Wind drift is kind of like that, but like he said, the time of flight is so short that the bullet won't match the crosswind speed until it's way, way WAY out there. Probably farther than any of us shoot.

Time of flight is important, definately. The point I was trying to make was it isn't as important to wind drift as it is to drop.

In the prior example, the 180 and the 240 have virtually the same time of flight out to 1550 yds. The 180 drops about 55" less. But it drifts about 60" more in the same crosswind.

BTW, my numbers differ from Darryl's because I printed the tables out in haste and by default they were corrected to 4400 ft elevation. [img]images/icons/wink.gif[/img] Things shoot flat up high. [img]images/icons/grin.gif[/img]
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  #21  
Old 06-14-2002, 08:07 AM
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Re: CALIBER CHOICES

JonA

I always choose a bullet that gives me the highest retained energy level to make clean kills at extreme range. This means I need the highest BC bullet in any diameter/caliber I choose.
The 180 will only give 683 Foot pounds at 1500yards and 600 at 1600 yards.
This bullet is out of the question at that range. Anything over 1200 yards with the 180 is out of the question.

The 240 will retain the energy and velocity better then any lower weight 30 cal at extended range.
Now if you program the 240 gr at what I shoot them at (3150 to 3200 FPS) you will see a complete difference in retained energy and velocity at ANY altitude.
Program in the 220gr which has a BC of .655 at 3200 fps and it too will beat the pants off the 180 Gr.

As you can tell, I like a heavy bullet with a high BC as I have seen what the difference is at yardages from 500 out to 2100 yards.

The 300 gr 338 (.800 BC) is my favorite so far but, I don't have the 408 on line yet. The action I want is the hold up for that one.

Velocity and energy are important and I think you will find that the heavy bullets with a high BC will retain both much better and perform the best on game at almost any range over 500 yards, especially on elk.

Another example of a lighter bullet was the 200 Gr I use to shoot in my 37" barrel, heavy actioned 30/378. I ran that bullet at 3600 fps and we made kills at 1360 on elk with it but, my self imposed yardage limit was 1400 yards as the energy level was down to 1068 foot pounds.
At 1400 yards with a 180 gr you only have 771 Foot pounds left.
That's why I gave up on the lighter bullets because I wanted to reach out further and not wound an animal and have him get away from us. The heavier, high BC bullets will kill faster, it seems, at most any range.

Darryl Cassel
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