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"This topic is dead..."
[/ QUOTE ] I don't think so (much as you would like it to be).
You know, Michael.
You whine about me being mean to you and being hard and confrontational.
But I wonder(ed) about it, so I went back the beginning of this thread and read it again.
Gustavo opened this thread with a very nice and polite question regarding some software he was working on. I don't know if he is the code writer, or just working on the math and has a code writer with him, but that's neither here nor there.
The point was that he asked a very polite question about (God forbid) software for LONG RANGE SHOOTING!!
And you promptly chewed his *** off!
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In short, when some programs shows downrange values beyond 2000 yards, my best educated estimate is that they rarely are confirmed by real firings.
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What good are my or your firing tests at beyond 2K going to do for anybody else? Unless they shoot the same caliber with the same bullets with the same twist with the same powder and the same primers at the same velocities, firing test only benefit the shooter doing the test.
As has been brought out MANY times here already, ballistic software will ONLY work for each user AFTER he has done his own tests with his own equipment. From there on, with an accurate BC and drag model for his own equipment, will he get accurate predictions for ever changing enviornmental conditions.
So to answer your original question. Without doing firing tests for each set of equipment, NO they cannot predict 2000 yard and beyond accuratly. My software cannot, yours cannot, exbal cannot, RSI cannot, sierra cannot. None. It is as simple as that. None ever will be either.
You must go do firing tests first for accurate predictions in other than your firing test conditions.
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Now, Michael... that was totally uncalled for - Gustavo was asking a polite question, and you pretty much said "Who the hell do you think you are, writing ballistic software... don't you know that you don't know
what I do, therefore you can't do it, and if you don't do it my way it is no good!"
Really low class, Michael. That was Confrontational! (I think that's the word you used)
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The point is catshooter, that in order for my tests to match yours, all things must be equal. That is all the point I am trying to make. Nothing more nothing less.
Differant powders and differant primers WILL yield differant velocities at differant twists. That is alot of variables. So if I test bullet "A" with all of my equipment, and you test that same bullet with yours, yes the results of BC and drag model WILL be differant.
Granted, most of the ballistic testing done on record has been done by the military, using VERY similar weapons and load components, so yeah, when using 168's and 175's and othe military match bullets from a 308 with similar twists and similar velocities, things are a little more predictable. Answer me this, when did the military use 178 AMAX's or bergers?? Or when did they use these bullets in a 300 RUM? You simply cannot say that all this ballistic research has been done over the last 100 years and that it is all predictable.
You say that makes ballistic software usless. If you are trying to hot a target at 1K with out first doing firing tests, youre right. They are useless.
You have to remember that the point of ballistic software is to accurately predict bullet flight in a new enviornment with real world BC's and drag models. Without those 2 key components, software generates a good guess. YOU CAN ONLY GET ACCURATE BC's AND DRAG MODELS FROM REAL WORLD FIRING TESTS.
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Michael... this is an odd thing coming from a guy that is touting his own software?
http://www.ratexenterprises.net/
Something about "Premium Ballistic software created for the long range hunter by a long range hunter".
Now tell us, Michael... with all this poo-poo about long range software being NO GOOD unless you check it first, are YOU going to match all these guys rifles to your software??
I mean, the GUI front page is nice, but what ballistic engine software is running behind it? You sure didn't write the basic code.
So I went on a search for your past posts...
Here's a goodie.
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12/14/05 12:01 PM
308 = 175 SMK @ 2700 FPS * 50 grains powder = 54 FPS per grain of powder.
30-378 = 175 SMK @ 3450 FPS * 100 grains powder = 34.5 FPS per grain of powder.
This illustrates how despite being slower in velocity, the 308 is much more efficient than the high velocity 30-378.
Twice the powder does not yeild twice the velocity. Why? Because bigger cases are less efficient.
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Now Michael - you should know that weight of powder does NOT compute as velocity, it relates to kinetic energy.
Hell, everyone in Ballistics know that.
Hell man, it's high school physics - you remember the energy increases by the exponent of the increase in speed.
Double the speed, four times the energy...
If you think you can put in double the energy (double the fuel) and come out with four times the energy, you have broken ALL the universal rules of physics, and there's buncha guys at Cal Tech and MIT that want to meet you.
So (following the boring rules of physics) the energy in a bullet at 3000 fps is FOUR TIMES the energy in a bullet at 1500 fps.
Using your example
175SMK @ 2700fps = 2832.3 ft/lps or 56.646 ft/lbs per grain.
175SMK @ 3450fps = 4624.3 ft/lbs or 46.243 ft/lbs per grain.
Not bad... the 30-378 has 81.635% efficiency of the 308.
But of course you know (or should know) the fly in the ointment. That is the EXPANSION RATIO!!
The 308 round has a capacity of about 68 grains of water, the 30-378 has about twice that.
Which means that the powder in the 30-378 can expand less than the powder in the 308, so it doesn't have the same chance to deliver it's energy to the projectile.
So the barrel volume of a 30 cal, 28' barrel (0.07258335774079999" x 28 = 2.032 (rounded off) cubic inches. Translate that to cubic centimeters
And you get...
308 case is ~3.24 cc
30-378 is ~6.48 cc
The barrel is 33.3 cc's
The expansion ratios are...
308 = 10.185:1
30-378 = 5.13.
So what we have is a case that has 1/2 the expansion ratio but delivers 81.6% of the energy. The 30-378 is NOT inefficient, it is VERY efficient. If it had a longer barrel, it would be close to equal in ft/lbs per grain.
So ... on this subject, you bombed out big time. You know nothing about internal ballistics!
I kept looking in the past archives, and what do I find, a while back you are asking the board how bullets fly, and how to handle Baro/temp issues.
Now that is not what one would expect from a self proclaimed expert that tells everybody else "What it is!!"
Michael, you are a novice at this.
You have a pretty faced piece of software product that you want to sell, so I guess you can write code, or know someone that can, but you don't know doodle squat about ballistics, internal or external.
How's that for confrontational.
Guys ask me to explain stuff, I have no problem doing it in scientific detail that most anyone, even a rank beginner, can understand... but ask you to explain something, and you tuck tail and run for cover.
You go around bluffing these guys all you want, but your theories don't fly.
You owe Gustavo an apology. He didn't deserve what you said to him.
If people listened to guys like you..."DON'T try that, cuz I say it won't work." then we'd all be in the dark ages and thinking 300 yds was a long shot.
There was a time when people DID think 300 yds was a long shot. But people that asked questions and thought, "Why can't I..." brought us to where we are now... and in ten years we will be further on and look back at these days and laugh.
Me... I got thick skin /ubbthreads/images/graemlins/wink.gif
So go pimp your software (and remember to test each guys rifle with it before you deliver it).
Meow.
