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Light, high BC bullet

 
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  #15  
Old 07-26-2001, 06:49 AM
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Join Date: May 2001
Location: Arco, ID 83213
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Re: Light, high BC bullet

txhunter,

It will be difficult using drawn-jacket, lead-core, swage technology to get a BC to .800, let alone above .900 or 1.00. There are limits to where these techniques can take you. We have .338 BCs in the high .800s, now, 30 cals. in the .900s and some new 50s way above 1.00. The tangential ogives used in those older methods are inferior ballistically at supersonic speed. Secant ogives are superior to Mach 5, or hypersonic velocities where cone ogives become superior. We can computer model a projectile to optimize it and when I have what I want I can input it to the big CNC and 5 minutes later I have that bullet in my hand to go test. If it needs adjustments I can do that very easily. I can do several design, manufacture and fire tests in an hour. Do you have any idea what the cycle time for drawn jacket technology is to do that same thing? It is weeks to months.

The difficulty is in the firearms, specifically, the barrels. Barrels have been refined for many, many years to shoot drawn jacket lead core bullets very accurately. Some of the things that make a barrel shoot lead core bullets very well, make shooting solid bullets difficult. For example, it is well know among barrel makers that to get top level benchrest accuracy you make the barrels to squeeze down on the bullet more than normal. You make a minimum dimension or subminimum dimension bore and groove. In .308, for example, you make a bore that is .300" or less and a groove that is .3076" or less. These tolerances cause me no end of headaches. I can get sub-quarter-minute groups at 400 and 500 yds with standard run-of-the-mill barrels, but when you use one these top of the line benchrest barrels the accuracy is terrible. Convincing the top barrels makers to start doing things differently than what they have learned, is also difficult. Custom fitting bullets for each barrel is time consuming. Eventually we will get there. I have proven to myself with several projects, the .408 being one, that this is the way of the future. The projectiles are simply superior.

The second thing that will have to be changed is the limitations of magazines and SAAMI specifications. Most of the limits on what can be done with a bullet and cartridge are set by the receiver that will be used. This too will changed with time.

Expect in the next 10 to 20 years that long range shooting will be done commonly with bullets that have BCs above 1.00.

[ 07-26-2001: Message edited by: Warren Jensen ]
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  #16  
Old 07-26-2001, 09:34 AM
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Join Date: Jul 2001
Location: San Antonio, Texas
Posts: 244
Re: Light, high BC bullet

Shot down again. Another idea gone down in flames. Oh well, the next one will be a ringer. I just know it. [img]images/icons/grin.gif[/img] [img]images/icons/grin.gif[/img]

Thanks for your time Warren! I know you probably have much more important things to do than to answer our questions and I don't know if you realize how much we apreciate your presence here. Having some one to bounce all of our hairbrained ideas off of is really nice if not convenient. Again Thanks.

PS. Are you sure that the laws of physics can't bent a little. Just this once. Please [img]images/icons/grin.gif[/img]

[ 07-26-2001: Message edited by: txhunter ]
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  #17  
Old 07-26-2001, 10:00 AM
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Join Date: May 2001
Location: Arco, ID 83213
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Re: Light, high BC bullet

Txhunter,

I think that stuff from burnt cookies that David mentioned may pierce the limits of known phenomena. I am pretty sure that some of that secret tank armor was made from such materials.
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  #18  
Old 07-26-2001, 12:53 PM
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Join Date: Jul 2001
Location: San Antonio, Texas
Posts: 244
Re: Light, high BC bullet

I just assembled the first round of 27/300 Ultra Mag. This thing looks like an intercontinential ballistic missle. That burned cooky heat shield material may come in handy after all.
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  #19  
Old 07-26-2001, 04:22 PM
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Join Date: Jun 2001
Location: Calgary, Alberta, Canada
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Re: Light, high BC bullet

So what is more important, BC or muzzle velocity?

Obviously having both factors fairly high will always result in a superior long-range projectile but if one has to compromise, which should take precedence?

I did a bit of informal research into BC and muzzle velocity. Both generally peak in the middle of the calibre range with conventional bullet designs. Off the top of my head I believe it was the .264 Mag that had the highest velocity with the highest BC bullet.

Peter Cronhelm
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  #20  
Old 07-26-2001, 07:58 PM
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Re: Light, high BC bullet

I'm of the belief that if you are going to keep your shooting inside 500 yards or so, you can get away with going for velocity and shoot lower BC bullets (within reason). If you are going long range, greater than 500 yards or so you need to seriously consider high BC bullets and sacrifice a little velocity.

Run several charts comparing one cartridges' bullet selections. Run light lower BC high velocity in comparison to heavy high BC lower velocity. (Actually weight is not the consideration, BC is what we need to compare but is hard to break the weight/BC bonding ritual.)
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  #21  
Old 07-26-2001, 09:47 PM
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Location: Calgary, Alberta, Canada
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Re: Light, high BC bullet

Isn't that the thing though? Every factor is related to every other factor and you can't gain in one without losing in another.

While BC is related to weight, weight has a stronger relation to muzzle velocity. More weight (usually) means a higher BC but it also means a lower MV.

In my case, I lucked out and found a 6mm bullet that had a high BC and weighed 12 grains less than the big 107gr MK.

The Berger 95 grain VLD has a BC equal to the bigger MK. So I can get ~100 fps more velocity without sacrificing BC. This is what allows me to take a .243 Win out to such outrageous distances.

The bullet reminds me of a tiny javelin.

FWIW I did an estimation of the energy of the 95 gr bullet at maximum distance and it is about equal to that of a .380 ACP handgun. Not exactly big game material but it could definatley do some damage with proper placement.

Peter
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