I want your help, and it involves doing a little bit of work.
We have all picked up a gun, thrown it to our shoulders, swung it around at some imaginary target and then exclaimed "That feels sweet" or "That's a very lively gun". Conversely we might say "That thing handles like a pig on a pitchfork" or "It feels like a 2X4". But what do we really mean when we say those things? How can that "feeling" be quantified?
The handling of a gun is distinctly different from how well it fits you. The drop at the comb or heel, the pitch of the butt or the amount of cast in the stock is irrelevant to the description of handling qualities. Stock dimensions can be altered to fit you, but changing them will not turn a "club" into a "wand".
When we talk about the handling characteristics of a shotgun we are really talking about its mass and balance - how the mass is distributed over the length of the gun. To describe that accurately requires a raft of information that is not really useful in everyday conversation. Saying "That feels like a 12 gauge with 28 inch barrels, a steel density of approximately 7.8*g/cm3 and a wall thickness of 0.030 inches 9 inches from the breech" does not enlighten anyone.
Manufacturers can evaluate the handling qualities of their products through the use of gimbal mounted cage which measures the forces required to accelerate the gun in all directions. The information gained from this apparatus is useful to engineers, but is not practical in a gun store.
Fortunately, an amazing gent by the name of Don Amos has derived a formula which represents the handling characteristics of any given shotgun as a single number. The number represents units of force (slug foot pounds per second) but that is irrelevant. What is important is that this method provides an easy way of describing and comparing handling traits.
Two tools are required to gather the data required by the formula - a tape measure and an accurate scale. The formula is set up for inches and pounds, so if you gather data in metric you will have to convert it before plugging in the numbers. Weighing the gun accurately is important, ordinary bathroom scales are not precise enough. Something capable of weighing in tenths of a pound is recommended. You will also require something to use as a fulcrum to determine the balance point of the gun.
The formula is:
0.34*(weight in lbs) + 0.07*(inches from (front) trigger to balance point) + 0.12*(length of pull) - 0.06*(bore diameter in inches) + 0.04*(barrel length in inches) - 0.03(if it is a sidelock, else 0) + 0.04(if it is a single barrel gun else 0) - 4.05 = result
The result of this equation is a number which can range from less than one (eg. 0.7955) to a high of about three (eg. 3.0122). Results in the 1.2 range indicate a lively game gun, a 3 indicates a heavy fowler and results less than 1 are very quick indeed.
In order to clarify the use of this formula we will measure a Caesar Guerini 20 gauge sporting clays model U/O (Magnus) and plug the numbers in to determine a result.
The scale reveals that the Guerini weighs 7.83 lbs.
We determine the balance point of the gun by placing it on a fulcrum (a triangular piece of 2X4 works well, but almost anything will work). Balancing the gun on your finger does not work well, you want to be able to determine the point of balance to within about 1/16th of an inch. Mark the balance point with chalk or tape, be as precise as you can.
Now we must measure the distance from the trigger to the balance point. This is measured from the rearmost point of the curve of the trigger (where your trigger finger makes contact with the blade) to the centre of balance. In the case of a double trigger, measure from the front trigger.
On the Guerini, the distance from the trigger to the balance point is 5.375 inches.
The length of pull is measured from the rearmost point of the curve of the trigger to the centre of the butt. In the case of a double trigger, measure from the front trigger. Our Guerini measures 14.5 inches exactly.
The next measurement which is required is the bore diameter. You probably do not have the tools required to actually measure the bore, but you can use the nominal bore diameter for the gauge. These diameters are:
10 ga. 0.775 inches
12 ga. 0.729 inches
16 ga. 0.663 inches
20 ga. 0.615 inches
28 ga. 0.550 inches
.410 0.410 inches
Of course if the actual bore diameter is known it is better to use that figure, but small variations in this number do not make great differences to the outcome. The formula largely uses this figure to determine the gauge of the gun.
In the case of our Guerini we will use the nominal bore dimension for a 20 gauge - 0.615 inches.
The length of the barrels on our example gun is 32.75 inches. If the gun is equipped with extended choke tubes, measure to the end of the tubes.
The Guerini is not a sidelock and it is not a single barreled gun, so the final two factors in the equation do not come in to play.
To review, our formula is:
0.34*(weight in lbs) + 0.07*(inches from (front) trigger to balance point) + 0.12*(length of pull) - 0.06*(bore diameter in inches) + 0.04*(barrel length in inches) - 0.03(if it is a sidelock, else 0) + 0.04(if it is a single barrel gun else 0) - 4.05
Plug in the numbers and we get:
0.34*(7.83 lbs) + 0.07*(5.375 inches) + 0.12*(14.5 inches) - 0.06*(0.615 inches) + 0.04*(32.75 inches) - 0 (it is not a sidelock) + 0(it is not a single barrel gun) - 4.05
Do the math and we get:
2.6622+0.37625+1.74-0.0369+1.31(-0+0)-4.05 = 2.00155 Pay attention to the plus and minus signs, if you add when you should subtract you will get odd results!
The result for our Guerini is 2.00155, and if we compare that to our expected range of results (1.2 equals a lively game gun, 3 equals a heavy goose gun) we see that a result of 2 is just about what we would expect from a long barreled sporting clays gun.
I have played with this formula for about a year now and have found it to be very reliable. Not perfect, but as good as it gets without elaborate test equipment. Most importantly, the results from the formula can be felt in your hands. Swing around a game gun rated 1.2 or so, and then compare it to the Guerini rated at 2.0 and the difference is immediately apparent. In fact, differences of about 0.01 on this scale can be felt, if you can compare the two back to back.
This information is useful in and of itself, but it becomes even more interesting when a number of guns can be compared. Of course a little .410 will produce a smaller number than a 12 gauge, but what if you want a 3 1/2 inch chambered pump with a 30 inch barrel for goose hunting. Which of the available models has the best handling? With a database of results from this formula, the question can be answered. We could also tell how consistent a manufacturer is. If 10 Gunnutz all measure their 12 gauge 870 Express models with 26 inch barrels and post the numbers, we could see how uniform the results are. The possibilities are endless, and the more guns there are to compare, the more useful the data becomes.
A useful report will include the make and model of the gun, its weight and barrel length and other salient features such as whether the gun is equipped with choke tubes, its chamber length and whether features such as aftermarket sights or shell holders have been added. It does not even have to be your gun, just one you can lay your hands on to measure.
This is not a contest. The lowest or any number does not "win". The numbers simply measure the ease with which a shotgun of a given gauge, weight and length can be handled. When comparing results within a given class of gun, a lower number might be considered a "winner", but remember that other factors (such as gun fit) must also be taken into consideration.
I will start with this short list and add more as soon as I can remember where I have filed them, or measure them. Remember, the more people who add to this list the more useful it becomes, and the more examples of a particular gun that are reported the better. Any and all shotguns are welcome.
Some results to get started:
Caesar Guerini Magnus Jaspe U/O, 7.83 lbs. 32.75 inch barrels with extended chokes, 3 inch chambers, result = 2.00155
Caesar Guerini Tempio Light U/O, 28 gauge 5.3 lbs, 26 inch barrels with 2 3/4 inch chambers, choke tubes, result = 0.80025
CZ Bobwhite, 28 gauge SxS, 5.36 lbs., 26 inch barrels with 2 3/4 inch chambers, choke tubes, half inch stock extension added, result = 0.93015
CZ Bobwhite 20 gauge SxS, 6.49 lbs. 26 inch barrels with 3 inch chambers, choke tubes, result = 1.259725
Army & Navy 20 gauge SxS, 5.76 lbs. 28 inch barrels with 2 1/2 inch chambers, fixed chokes, result = 1.03435
Stevens 311 20 gauge SxS, 6.825 lbs. 25.75 inch barrels with 2 3/4 inch chambers, fixed chokes, result = 1.3086
If enough people respond to this thread I will tabulate the data and post it in a downloadable file for all Gunnutz to use. If you have read this far, thank you for your attention and I look forward to your input. Any questions or comments are also welcome.
Sharptail
We have all picked up a gun, thrown it to our shoulders, swung it around at some imaginary target and then exclaimed "That feels sweet" or "That's a very lively gun". Conversely we might say "That thing handles like a pig on a pitchfork" or "It feels like a 2X4". But what do we really mean when we say those things? How can that "feeling" be quantified?
The handling of a gun is distinctly different from how well it fits you. The drop at the comb or heel, the pitch of the butt or the amount of cast in the stock is irrelevant to the description of handling qualities. Stock dimensions can be altered to fit you, but changing them will not turn a "club" into a "wand".
When we talk about the handling characteristics of a shotgun we are really talking about its mass and balance - how the mass is distributed over the length of the gun. To describe that accurately requires a raft of information that is not really useful in everyday conversation. Saying "That feels like a 12 gauge with 28 inch barrels, a steel density of approximately 7.8*g/cm3 and a wall thickness of 0.030 inches 9 inches from the breech" does not enlighten anyone.
Manufacturers can evaluate the handling qualities of their products through the use of gimbal mounted cage which measures the forces required to accelerate the gun in all directions. The information gained from this apparatus is useful to engineers, but is not practical in a gun store.
Fortunately, an amazing gent by the name of Don Amos has derived a formula which represents the handling characteristics of any given shotgun as a single number. The number represents units of force (slug foot pounds per second) but that is irrelevant. What is important is that this method provides an easy way of describing and comparing handling traits.
Two tools are required to gather the data required by the formula - a tape measure and an accurate scale. The formula is set up for inches and pounds, so if you gather data in metric you will have to convert it before plugging in the numbers. Weighing the gun accurately is important, ordinary bathroom scales are not precise enough. Something capable of weighing in tenths of a pound is recommended. You will also require something to use as a fulcrum to determine the balance point of the gun.
The formula is:
0.34*(weight in lbs) + 0.07*(inches from (front) trigger to balance point) + 0.12*(length of pull) - 0.06*(bore diameter in inches) + 0.04*(barrel length in inches) - 0.03(if it is a sidelock, else 0) + 0.04(if it is a single barrel gun else 0) - 4.05 = result
The result of this equation is a number which can range from less than one (eg. 0.7955) to a high of about three (eg. 3.0122). Results in the 1.2 range indicate a lively game gun, a 3 indicates a heavy fowler and results less than 1 are very quick indeed.
In order to clarify the use of this formula we will measure a Caesar Guerini 20 gauge sporting clays model U/O (Magnus) and plug the numbers in to determine a result.
The scale reveals that the Guerini weighs 7.83 lbs.
We determine the balance point of the gun by placing it on a fulcrum (a triangular piece of 2X4 works well, but almost anything will work). Balancing the gun on your finger does not work well, you want to be able to determine the point of balance to within about 1/16th of an inch. Mark the balance point with chalk or tape, be as precise as you can.
Now we must measure the distance from the trigger to the balance point. This is measured from the rearmost point of the curve of the trigger (where your trigger finger makes contact with the blade) to the centre of balance. In the case of a double trigger, measure from the front trigger.
On the Guerini, the distance from the trigger to the balance point is 5.375 inches.
The length of pull is measured from the rearmost point of the curve of the trigger to the centre of the butt. In the case of a double trigger, measure from the front trigger. Our Guerini measures 14.5 inches exactly.
The next measurement which is required is the bore diameter. You probably do not have the tools required to actually measure the bore, but you can use the nominal bore diameter for the gauge. These diameters are:
10 ga. 0.775 inches
12 ga. 0.729 inches
16 ga. 0.663 inches
20 ga. 0.615 inches
28 ga. 0.550 inches
.410 0.410 inches
Of course if the actual bore diameter is known it is better to use that figure, but small variations in this number do not make great differences to the outcome. The formula largely uses this figure to determine the gauge of the gun.
In the case of our Guerini we will use the nominal bore dimension for a 20 gauge - 0.615 inches.
The length of the barrels on our example gun is 32.75 inches. If the gun is equipped with extended choke tubes, measure to the end of the tubes.
The Guerini is not a sidelock and it is not a single barreled gun, so the final two factors in the equation do not come in to play.
To review, our formula is:
0.34*(weight in lbs) + 0.07*(inches from (front) trigger to balance point) + 0.12*(length of pull) - 0.06*(bore diameter in inches) + 0.04*(barrel length in inches) - 0.03(if it is a sidelock, else 0) + 0.04(if it is a single barrel gun else 0) - 4.05
Plug in the numbers and we get:
0.34*(7.83 lbs) + 0.07*(5.375 inches) + 0.12*(14.5 inches) - 0.06*(0.615 inches) + 0.04*(32.75 inches) - 0 (it is not a sidelock) + 0(it is not a single barrel gun) - 4.05
Do the math and we get:
2.6622+0.37625+1.74-0.0369+1.31(-0+0)-4.05 = 2.00155 Pay attention to the plus and minus signs, if you add when you should subtract you will get odd results!
The result for our Guerini is 2.00155, and if we compare that to our expected range of results (1.2 equals a lively game gun, 3 equals a heavy goose gun) we see that a result of 2 is just about what we would expect from a long barreled sporting clays gun.
I have played with this formula for about a year now and have found it to be very reliable. Not perfect, but as good as it gets without elaborate test equipment. Most importantly, the results from the formula can be felt in your hands. Swing around a game gun rated 1.2 or so, and then compare it to the Guerini rated at 2.0 and the difference is immediately apparent. In fact, differences of about 0.01 on this scale can be felt, if you can compare the two back to back.
This information is useful in and of itself, but it becomes even more interesting when a number of guns can be compared. Of course a little .410 will produce a smaller number than a 12 gauge, but what if you want a 3 1/2 inch chambered pump with a 30 inch barrel for goose hunting. Which of the available models has the best handling? With a database of results from this formula, the question can be answered. We could also tell how consistent a manufacturer is. If 10 Gunnutz all measure their 12 gauge 870 Express models with 26 inch barrels and post the numbers, we could see how uniform the results are. The possibilities are endless, and the more guns there are to compare, the more useful the data becomes.
A useful report will include the make and model of the gun, its weight and barrel length and other salient features such as whether the gun is equipped with choke tubes, its chamber length and whether features such as aftermarket sights or shell holders have been added. It does not even have to be your gun, just one you can lay your hands on to measure.
This is not a contest. The lowest or any number does not "win". The numbers simply measure the ease with which a shotgun of a given gauge, weight and length can be handled. When comparing results within a given class of gun, a lower number might be considered a "winner", but remember that other factors (such as gun fit) must also be taken into consideration.
I will start with this short list and add more as soon as I can remember where I have filed them, or measure them. Remember, the more people who add to this list the more useful it becomes, and the more examples of a particular gun that are reported the better. Any and all shotguns are welcome.
Some results to get started:
Caesar Guerini Magnus Jaspe U/O, 7.83 lbs. 32.75 inch barrels with extended chokes, 3 inch chambers, result = 2.00155
Caesar Guerini Tempio Light U/O, 28 gauge 5.3 lbs, 26 inch barrels with 2 3/4 inch chambers, choke tubes, result = 0.80025
CZ Bobwhite, 28 gauge SxS, 5.36 lbs., 26 inch barrels with 2 3/4 inch chambers, choke tubes, half inch stock extension added, result = 0.93015
CZ Bobwhite 20 gauge SxS, 6.49 lbs. 26 inch barrels with 3 inch chambers, choke tubes, result = 1.259725
Army & Navy 20 gauge SxS, 5.76 lbs. 28 inch barrels with 2 1/2 inch chambers, fixed chokes, result = 1.03435
Stevens 311 20 gauge SxS, 6.825 lbs. 25.75 inch barrels with 2 3/4 inch chambers, fixed chokes, result = 1.3086
If enough people respond to this thread I will tabulate the data and post it in a downloadable file for all Gunnutz to use. If you have read this far, thank you for your attention and I look forward to your input. Any questions or comments are also welcome.
Sharptail
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