Chris Nolin
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Well, I was interested in knowing exactly what was meant by the phrase and I think I've got it. Thanks all!
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Diminishing Returns?
- Thread starter Chris Nolin
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Larry
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Lapoudre said:
So your trying to tell us that you have what you needed & further posting will likely yield Diminishing Returns :wink:
Chris Nolin
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That's fantastic stuff! I wish I'd thought of it. Thanks!
I'm surprised you don't recall where the 11.5 came from.
You've been here long enough to remember Paul Vallandigham and his presentations on the Davenport Formula.
Before we get off on a tangent discussing the Davenport Formula (Paul's own name for it because he knew a Mr. Davenport that worked it out.), we should remember that Paul never said it was a hard number that could not be exceeded.
He said the Davenport Formula was to be used to find a starting point for the most accurate target shooting powder load. That's all it ever was.
Now, back to regularly scheduled program. :grin:
You've been here long enough to remember Paul Vallandigham and his presentations on the Davenport Formula.
Before we get off on a tangent discussing the Davenport Formula (Paul's own name for it because he knew a Mr. Davenport that worked it out.), we should remember that Paul never said it was a hard number that could not be exceeded.
He said the Davenport Formula was to be used to find a starting point for the most accurate target shooting powder load. That's all it ever was.
Now, back to regularly scheduled program. :grin:
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+1 :thumbsup:
Billnpatti
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This is what the late Paul Valindigham had to say back on September 22, 2010"
"09-22-10 05:13 PM - Post#898329
According to Phil Quaglino, There is NO simple answer. Leave it there. Phil is the retired Champion Rifle and Pistol Shooter, who gave my brother, Peter, the Davenport formula to put on this forum. He wanted this information available to all MLers for what its worth. He got the formula from Another NMLRA former President, who knew Charles Davenport personally.
None of these older shooters had access to chronographs. These kinds of rules of thumbs were passed down as " secrets", shared with the top shooters at matches. The maximum Efficient Load, which the formula gives for a given bore diameter and given barrel length allows a shooter to have some idea of that amount of powder- regardless of grain size-- that will give the best group accuracy. That usually means, in today's Chronograph culture, " the lowest SDV" for a given barrel length, caliber, and powder charge.
Like you, and your friends, I am a born Skeptic. I find it hard to believe that this works for both PRB AND bullets, with both 2Fg and 3Fg, much less Fg powders.
Use the Davenport formula to help you decide what barrel length you need to get a certain range of velocity. Then use your chronograph. There seems to be a "Point of Diminishing returns" in powder charges where the Davenport formula says it should be, regardless of powder used. This is where there is an apparent drop in the amount of velocity gained for each increment of powder added to your charge.
However, its also clear that you can get more velocity( and much more recoil) by adding more powder to your charge. If pure velocity is what you want, IGNORE the Davenport formula, and load away!
I have met people of questionable judgment who are putting Smokeless Powder down their MLers, and even 4Fg powder down the barrel, even when they know that these kinds of powder are Specifically NOT to be used in MLers.
The Comedian, Ron White claims,
" You can't fix stupid",
and he may be right. I will keep trying, but I am no longer surprised at what people are willing to risk and do to "Prove they are right". A lot of gunsmiths would have a hard time paying their bills if it weren't for these kinds of gun owners.
I have tried to show the Point of diminishing returns using standard data from other sources. Basically, you form a column that represents the Increase of Velocity for each 10 grain increase in powder charge for a given gun. You need a chronograph to do this with your own gun, however. The Maximum Efficient Powder charge is reached before the Point of diminishing returns, or where the increase in velocity begins to drop off.
I do believe that there is some change when using 3Fg vs. 2Fg, and when comparing the data for shooting a PRB vs. a bullet. If you add an OP wad, or filler, to the load, I believe this causes an increase in the velocity, due to more efficient burning of the powder, higher breech pressure, and a bit of "Lag time " in the barrel when these changes are added to the traditional PRB. The lag time relates to a millisecond of time it takes for the gases to overcome the inertia( mass, and coefficient of friction) of the filler or OP wad in addition to that of the PRB or bullet. Because flintlocks are "Open ignition systems" with a large vent hole at the rear of the barrel to "release pressure" to some extent, you get less of a velocity increase using a flintlock with these additional components, than when using a "closed" percussion ignition. However, the chronograph still shows a increase in MV when OP wads, or fillers are used in flintlocks, both rifles and smoothbores.
Because 3Fg powder burns faster than 2Fg , the same volume measure of the two powders will see the 3Fg powder burning faster, and hotter( higher breech pressure), so that you need to reduce the amount of 3Fg powder used to get the same MV that you would expect from the same gun using 2Fg powder instead. Otherwise,looking at the two different powders is comparing apples to oranges. That factor is often one overlooked in these discussions about the Point of diminishing returns, and the Davenport formula.
For NEW Readers, who are wondering what the HECK we are talking about, the Davenport Formula says that the MAXIMUM EFFICIENT powder charge that a given caliber and given barrel length is determined by using the formula:
11.5 grains of BLACK POWDER per cubic Inch of barrel.
If you use a chronograph, this formula gives you the powder charge for a given gun, where The gun will shoot the smallest groups, with the smallest Standard Deviation in Velocity for a series of shots, at a MV where you do not exceed the Point of diminishing returns when you increase the amount of the powder charge. The point of diminishing returns in MV should be fairly common for all powders, since its based on barrel harmonics( vibrations created by the forces of the powder gases pushing against the walls of the bore) to a great extent.
Because 3Fg powder burns Hotter, and Faster than does a comparable Volume load of 2Fg powder, you are going to find a different Powder load with each powder chosen( volume and by weight) using the two different powders. The same will happen using Swiss powders, because they also burn hotter, and faster, than American made powders do.
Oh, later Phil mentioned that in his personal experience using the formula, he found you can use the formula as is to predict accurate powder charge with Flintlocks, but the most accurate load using a percussion rifle( same caliber, same barrel length) will be about 10 % less than the formula predicts.
I hope this helps. I really did not want to have to write about this again. I apologize to all the older members for this, again.
Paul "
"09-22-10 05:13 PM - Post#898329
According to Phil Quaglino, There is NO simple answer. Leave it there. Phil is the retired Champion Rifle and Pistol Shooter, who gave my brother, Peter, the Davenport formula to put on this forum. He wanted this information available to all MLers for what its worth. He got the formula from Another NMLRA former President, who knew Charles Davenport personally.
None of these older shooters had access to chronographs. These kinds of rules of thumbs were passed down as " secrets", shared with the top shooters at matches. The maximum Efficient Load, which the formula gives for a given bore diameter and given barrel length allows a shooter to have some idea of that amount of powder- regardless of grain size-- that will give the best group accuracy. That usually means, in today's Chronograph culture, " the lowest SDV" for a given barrel length, caliber, and powder charge.
Like you, and your friends, I am a born Skeptic. I find it hard to believe that this works for both PRB AND bullets, with both 2Fg and 3Fg, much less Fg powders.
Use the Davenport formula to help you decide what barrel length you need to get a certain range of velocity. Then use your chronograph. There seems to be a "Point of Diminishing returns" in powder charges where the Davenport formula says it should be, regardless of powder used. This is where there is an apparent drop in the amount of velocity gained for each increment of powder added to your charge.
However, its also clear that you can get more velocity( and much more recoil) by adding more powder to your charge. If pure velocity is what you want, IGNORE the Davenport formula, and load away!
I have met people of questionable judgment who are putting Smokeless Powder down their MLers, and even 4Fg powder down the barrel, even when they know that these kinds of powder are Specifically NOT to be used in MLers.
The Comedian, Ron White claims,
" You can't fix stupid",
and he may be right. I will keep trying, but I am no longer surprised at what people are willing to risk and do to "Prove they are right". A lot of gunsmiths would have a hard time paying their bills if it weren't for these kinds of gun owners.
I have tried to show the Point of diminishing returns using standard data from other sources. Basically, you form a column that represents the Increase of Velocity for each 10 grain increase in powder charge for a given gun. You need a chronograph to do this with your own gun, however. The Maximum Efficient Powder charge is reached before the Point of diminishing returns, or where the increase in velocity begins to drop off.
I do believe that there is some change when using 3Fg vs. 2Fg, and when comparing the data for shooting a PRB vs. a bullet. If you add an OP wad, or filler, to the load, I believe this causes an increase in the velocity, due to more efficient burning of the powder, higher breech pressure, and a bit of "Lag time " in the barrel when these changes are added to the traditional PRB. The lag time relates to a millisecond of time it takes for the gases to overcome the inertia( mass, and coefficient of friction) of the filler or OP wad in addition to that of the PRB or bullet. Because flintlocks are "Open ignition systems" with a large vent hole at the rear of the barrel to "release pressure" to some extent, you get less of a velocity increase using a flintlock with these additional components, than when using a "closed" percussion ignition. However, the chronograph still shows a increase in MV when OP wads, or fillers are used in flintlocks, both rifles and smoothbores.
Because 3Fg powder burns faster than 2Fg , the same volume measure of the two powders will see the 3Fg powder burning faster, and hotter( higher breech pressure), so that you need to reduce the amount of 3Fg powder used to get the same MV that you would expect from the same gun using 2Fg powder instead. Otherwise,looking at the two different powders is comparing apples to oranges. That factor is often one overlooked in these discussions about the Point of diminishing returns, and the Davenport formula.
For NEW Readers, who are wondering what the HECK we are talking about, the Davenport Formula says that the MAXIMUM EFFICIENT powder charge that a given caliber and given barrel length is determined by using the formula:
11.5 grains of BLACK POWDER per cubic Inch of barrel.
If you use a chronograph, this formula gives you the powder charge for a given gun, where The gun will shoot the smallest groups, with the smallest Standard Deviation in Velocity for a series of shots, at a MV where you do not exceed the Point of diminishing returns when you increase the amount of the powder charge. The point of diminishing returns in MV should be fairly common for all powders, since its based on barrel harmonics( vibrations created by the forces of the powder gases pushing against the walls of the bore) to a great extent.
Because 3Fg powder burns Hotter, and Faster than does a comparable Volume load of 2Fg powder, you are going to find a different Powder load with each powder chosen( volume and by weight) using the two different powders. The same will happen using Swiss powders, because they also burn hotter, and faster, than American made powders do.
Oh, later Phil mentioned that in his personal experience using the formula, he found you can use the formula as is to predict accurate powder charge with Flintlocks, but the most accurate load using a percussion rifle( same caliber, same barrel length) will be about 10 % less than the formula predicts.
I hope this helps. I really did not want to have to write about this again. I apologize to all the older members for this, again.
Paul "
Patocazador
54 Cal.
Can this be expressed mathematically by the formula: 11.5(L x B*) where L= barrel length, B= bore diameter, and *= squared???
I do remember where it came from on the forum. It came from Paul. Even Paul didn't know where it came from in the mind of the old target shooter who supposedly figured it out, though, or if he did, never said. I believe he said he didn't know. Like many of these supposedly magic formulas, it was just stated as fact.Zonie said:
I disagreed with Paul then, and told him so. I disagree with him now. I miss Paul. The forum is a much less interesting place without him.
Spence
Billnpatti
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Nope, the formula for the volume of a cylinder is Pi r squared h. So you would have to change the B to B/2 because you use the radius squared not the diameter squared . Of course, in this case, the height of the cylinder is the length of the barrel. Therefore, your formula would be:
11.5{Pi[L X (B/2)*]}
Example: Assume a .50 caliber barrel that is 28 inches long. The radius is 1/2 the diameter or .25. .25 squared is 0.0625. So Pi times 0.0625 times 28 is 3.1416 X .0625 X 28= 5.4978 or roughly 5 1/2 cubic inches of bore volume. Multiply this number by 11.5 and you get 5.5 X 11.5 = 63.25. Round that off to 63 grains. Theoretically, that is an approximation of how much powder that particular barrel can burn efficiently.
11.5{Pi[L X (B/2)*]}
Example: Assume a .50 caliber barrel that is 28 inches long. The radius is 1/2 the diameter or .25. .25 squared is 0.0625. So Pi times 0.0625 times 28 is 3.1416 X .0625 X 28= 5.4978 or roughly 5 1/2 cubic inches of bore volume. Multiply this number by 11.5 and you get 5.5 X 11.5 = 63.25. Round that off to 63 grains. Theoretically, that is an approximation of how much powder that particular barrel can burn efficiently.
galamb
58 Cal.
All of this discussion is academic anyhow (but it is an interesting discussion).
If an individual truly wants to shoot a max load they owe it to themselves and their quarry to do a few things.
First, practice with that charge. If they develop a flinch or a pull, correct that.
Second, learn how to estimate distance accurately, like within 5 yards (which is super difficult if not impossible to do) - 5 or 10 yards may not make much of a difference up to 70 yards or so, but at 100 and beyond it can mean a hit, clear miss or a non-lethal hit (so maybe use a laser range finder).
Third, chrono your rifle with the load, patch, projectile, lube etc that you plan to use to shoot that max charge at/greater than 100 yards.
IF shooting a 50 cal, with .490 RB gives you a max velocity of say 1830 fps with a 110 grain load but has a deviation of 50 fps, the second shot may only be 1780 fps with the others falling somewhere in between.
1780 fps is achievable with a 100 grain load (Lyman manual - all else being equal).
So you have to ask yourself. If you "don't know" what the deviation is would you spend the summer before hunting season practicing with 110 grains of powder then only pour 100 grains down the muzzle on "opening day" ??
What is the projectile going to do?
The chrono will tell you whether that 110 grains gives you consistent/close results or if maybe 100 is "far more accurate" or maybe it's just 90 grains.
And when you pull the trigger if that ball only got the benefit of your "lowest velocity" and Bambi is standing at 110 yards instead of 100 you could spend a long day tracking a poor blood trail and possibly never recover the animal at all.
So if 100 grains gives you a deviation of 7 fps and 110 gives you a deviation of 50 fps, wouldn't that be "another" diminishing return??
If an individual truly wants to shoot a max load they owe it to themselves and their quarry to do a few things.
First, practice with that charge. If they develop a flinch or a pull, correct that.
Second, learn how to estimate distance accurately, like within 5 yards (which is super difficult if not impossible to do) - 5 or 10 yards may not make much of a difference up to 70 yards or so, but at 100 and beyond it can mean a hit, clear miss or a non-lethal hit (so maybe use a laser range finder).
Third, chrono your rifle with the load, patch, projectile, lube etc that you plan to use to shoot that max charge at/greater than 100 yards.
IF shooting a 50 cal, with .490 RB gives you a max velocity of say 1830 fps with a 110 grain load but has a deviation of 50 fps, the second shot may only be 1780 fps with the others falling somewhere in between.
1780 fps is achievable with a 100 grain load (Lyman manual - all else being equal).
So you have to ask yourself. If you "don't know" what the deviation is would you spend the summer before hunting season practicing with 110 grains of powder then only pour 100 grains down the muzzle on "opening day" ??
What is the projectile going to do?
The chrono will tell you whether that 110 grains gives you consistent/close results or if maybe 100 is "far more accurate" or maybe it's just 90 grains.
And when you pull the trigger if that ball only got the benefit of your "lowest velocity" and Bambi is standing at 110 yards instead of 100 you could spend a long day tracking a poor blood trail and possibly never recover the animal at all.
So if 100 grains gives you a deviation of 7 fps and 110 gives you a deviation of 50 fps, wouldn't that be "another" diminishing return??
Billnpatti
Cannon
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As a physics professor of mine used to say "Damn well said."
I'm so "old school", the tightest group is all I care about. I'm not interested in velocity, foot pounds or formulas. I'll leave that to the guys in the laboratory. :wink:galamb said:
I'm so "old school", the tightest group is all I care about. I'm not interested in velocity, foot pounds or formulas. I'll leave that to the guys in the laboratory.
Same here! :thumbsup:
Same here! :thumbsup:
In fact, just got the ballistol from TOW and reading dutchs dry patch now...be soaking patches here soon!
Patocazador
54 Cal.
Thanks. I was treating it as a square tube instead of a round one. 
galamb
58 Cal.
Once again that is perspective.
IF I am only sighting at 50 yards and IF I only require an accuracy of +/- 2" at that distance and IF I know that I tend to pull 1" high and right with every shot and IF I have determined that my 2" point blank range is +/- 2" above/below line of sight out to 70 yards.
All of which is more than sufficient to place a kill shot in the 8'ish inch circle that represents the vital area of Bambi IF I aim for the center of that area (given all the potential error from point of aim that I have specified).
And knowing all that, IF I don't try a "hail Mary" shot, at last light on closing day at an unknown distance -
Then given all that, IF the "most efficient" load, as calculated by the formula will produce those results, then there is no need to exceed it and venture into the area of "diminishing returns".
But IF my wants/needs are different from above then "I" need to spend time on the range with a chrono figuring that out - because asking "Bob" what works for him is of little to no value to ME.
There is a commercial about gambling up my way. The message is "Know Your Limit and Play Within It".
With ML's you need to figure out what your limit is for yourself - nobody can answer that for you with formulae, charts, graphs or antidotes.
IF I am only sighting at 50 yards and IF I only require an accuracy of +/- 2" at that distance and IF I know that I tend to pull 1" high and right with every shot and IF I have determined that my 2" point blank range is +/- 2" above/below line of sight out to 70 yards.
All of which is more than sufficient to place a kill shot in the 8'ish inch circle that represents the vital area of Bambi IF I aim for the center of that area (given all the potential error from point of aim that I have specified).
And knowing all that, IF I don't try a "hail Mary" shot, at last light on closing day at an unknown distance -
Then given all that, IF the "most efficient" load, as calculated by the formula will produce those results, then there is no need to exceed it and venture into the area of "diminishing returns".
But IF my wants/needs are different from above then "I" need to spend time on the range with a chrono figuring that out - because asking "Bob" what works for him is of little to no value to ME.
There is a commercial about gambling up my way. The message is "Know Your Limit and Play Within It".
With ML's you need to figure out what your limit is for yourself - nobody can answer that for you with formulae, charts, graphs or antidotes.
You seem to have it all worked out, in your head at least. Maybe you are the guy I've been looking for, the one who can answer the one central question in all these discussions about "efficient" loads... where does the constant in the formula, 11.5 grains of powder per cubic inch of bore come from? How was that determined to be true? To me, it seems like the factor one always finds in these magic formulas which has to be taken on faith, accepted as fact with no explanation, "just because." If you will offer up a reasonable explanation for that I'll shut up and go away. Otherwise, I'm planting a stake and collecting tar and fagots. :haha:
Spence
Spence
