What makes a cartridge efficient
- Thread starter calgarycanada
- Start date
Apparently your wrong. I was told I was My crony said different . I. Put a hemispherical shoulder on WSSM it held the same capacity as the parent case . Useing the same powder and bullet . Only difference was the barrel was set back to accomdate the shoulder .
It was 11 fps faster . Oh Well what do we know . Larry
I've been wrong before so it doesn't surprise me... I said it was my 'understanding' meaning it was something I read in one of the many gun magazinesand not necessarily my opinion. I never said that it was gospel. The question was "what makes an efficient cartridge?" My main point was MANY THINGS make a cartridge efficient. The cartridge is a combination of components so unless all work in sync no matter the shape it won't be efficient.
Energy, not velocity.
dmoran
Donovan Moran
Larry -
Now that's funny..... 11-fps would be less than 1/2 percent of efficiency variation !.!.!.!
A tenth of mis-calculation to any of the comparable variables, would more then account for 11-fps, let alone atmospheric variances from one chronograph session to the other (like Tom alluded to).
Chronograph error factors are larger then that, and your extreme spreads could more then account for that minor of variation.
In actuality, you proved that changing the shoulder shape/angle had nil effect on combustion or efficiency.
The accuracy differences between the two that you had on the targets would prove which shoulder shape/angle proved out better with that barrel and component combination, which no doubt was a good find for you !.!.!
Good stuff..... Thanks
Donovan
Edit: PS to Tom -
Did you figure your " .004% WOW " based on 3000-fps ?
I just divided 11 into 3000 and that's what I got:
(11 / 3000 = 0.0036666666666667%)
A very minuscule variation indeed, to say the least !.!.!
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If same bullet is used, energy is directly proportional to energy.
Very good responses above. Especially "everything has to work in sync" . But what factors determine it? Why haven't we been able to make other cases as good as Dasher? I with more capacity.
Bryan, would you like to shine some light on the subject?
IF not energy, what accounts for the velocity delta between the two on an object of identical mass?
For the intent & purpose of my post, measured velocity is directly attributable to ENERGY.
Which, has everything to do with the powder used, and little/nothing to do the with cartridge itself...
Therefore, if a different powder can make a cartridge appear more "efficient" by generating more velocity (energy) with less volume, how is it that the cartridge itself is determinated as being "more efficient" than another???
I'm of the same opinion as others above. There's more to "efficiency" than cartridge design alone. Powder selection, bullet weight, barrel length, etc... all factor into observed results...
Velocity and energy are just two units of measurement when looking at efficiency. For me it all boils down to whether a particular cartridge shoots accurately out of a weapon. You could have a cartridge that fires a 150 gr bullet at 3,000fps using very little powder, but if that cartridge sucks at hitting point of aim just how efficient is it? It is a well known fact that when hunting placement of the projectile is more important than diameter or how fast it is moving. Same with target shooting. Accuracy, at least for me is the determining factor. Not how fast it goes. Like I have said before the cartridge is also only as efficient as the weapon it is loaded into. What might be an extremely efficient killer/bullseye puncher in one rifle might be worthless in another. Too many variables involved for anyone to say one factor over another makes a cartridge efficient.
Here's my way of determining, it's probably wrong but that's the way I think,
Cartridge "A" pushes bullet "X" at 3000 fps and uses 30 grains of any powder.
If Cartridge "B" CAN'T push same bullet "X" at 4000 fps using 40 grains of any powder(different powder-slower), that means cartridge "B" is not as efficient as cartridge "A".
Energy is one way to judge but it's used when different (weight) projectiles are compared. If same bullet is being compared energy numbers will be directly related to velocity because
Energy(kinetic)=1/2 M(mass) X V^2(velocity squared). So in my comparison only number we are changing is velocity in that equation.
Your math incorrectly assumes a linear relationship with velocity and energy content per unit of mass. This is not so.
Scott Parker
Now Donovan, don't start to mention that the 11fps deviation is well within the error of his chronograph. Everyone knows that if the digital display says it, it must be true.
Scott Parker
Sorry I didn't understand, are we talking about energy content per unit of powder mass?
it is implied in your comparison of velocities of the same bullet of mass A loaded with 30 grains of powder to give 3000fps and 40 grains of powder to give 4000fps.
From what info I have been able to find,
Cartridge efficiency is defined as:
velocity - per powder weight, at a given bullet weight:
another variable that could enter into the problem is how much pressure a case is rated for.
The 22 RF Short case was stated to be as the most efficient case,
29 gr bullet @ 1045 fps using 4.0 gr BP from a 22" bbl, 21000 chamber psi = 28.1%
For an example,
Which of these cases/calibers is the most efficient?
All the below have the same bullet weight, same bbl length and,
use the same powder and have the same chamber pressure,
and same case size.
17 cal-29gr @ 21000 psi-22" bbl= 1841fps= 2.85 grs of powder = % of ballistic efficiency?
20 cal-29gr @ 21000 psi-22" bbl= 1964fps= 3.94 grs of powder = % of ballistic efficiency?
22 cal-29gr @ 21000 psi-22" bbl= 2098fps= 5.07 grs of powder = % of ballistic efficiency?
Tia,
Don
Cartridge efficiency is defined as:
velocity - per powder weight, at a given bullet weight:
another variable that could enter into the problem is how much pressure a case is rated for.
The 22 RF Short case was stated to be as the most efficient case,
29 gr bullet @ 1045 fps using 4.0 gr BP from a 22" bbl, 21000 chamber psi = 28.1%
For an example,
Which of these cases/calibers is the most efficient?
All the below have the same bullet weight, same bbl length and,
use the same powder and have the same chamber pressure,
and same case size.
17 cal-29gr @ 21000 psi-22" bbl= 1841fps= 2.85 grs of powder = % of ballistic efficiency?
20 cal-29gr @ 21000 psi-22" bbl= 1964fps= 3.94 grs of powder = % of ballistic efficiency?
22 cal-29gr @ 21000 psi-22" bbl= 2098fps= 5.07 grs of powder = % of ballistic efficiency?
Tia,
Don
But what about exterior ballistics and terminal performance? Everything looks good on paper, but what does it do on the downrange side? Efficiency, at least for me is more the effect the bullet has on my target. You can't measure overall cartridge efficiency based on velocity for a given weight powder on a given weight projectile. For example, is a full metal jacketed bullet as efficient at killing quickly than a soft point expanding? Fore both out of a .308W using the same load at the same velocity. Both will kill, but which is more efficient at it? Two different primers may start a 155 gr match bullet out a barrel at the same velocity using the same powder and charge weights, but one shoots tight groups and the other shitty groups. Efficiency is but one thing.. Performance downrange. Temperature is another variable. What is an extremely efficient super good shooting cartridge today at 75 degreesF may be the worst ever next month at 25F. Again. Too many variables to pin down just what make a cartridge efficient.
Wouldn't that be like putting a gallon of gas in two different cars and one going 14 miles and the other going 20. Larry
Maybe efficient at going faster with less powder, but in the shooting world where everything is based on group sizes what is fast isn't always the best performing and doesn't necessarily correlate to being efficient if it isn't accurate as well.
The small one is the Dasher. Usually the one that goes faster with less powder is also more accurate. Matt
I think the 6 PPC fits also .Larry
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