doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Balance at hingepin question

"Why is the balance point of a double so important at the hingepin"

Because,,, if the gun does not balance on the hinge-pin it will fall off the top your shoulder when trying to use two hands.

Mark,
Now that's a sensible comment...thanks.

Sharp,

I'm being very serious. We can talk all about why and why not but when you're in the field those things are very important, at least to me. A gun that balances just a mere inch forward of the hinge pin will not balance on your shoulder or the crook of your arm.

Three or four years ago the owner of a range nearby handed me her gun. It was a Krieghoff O/U and she said mount the gun and tell me what you think. I responded that it was extemely light and very fast. I'll be darned if I understand how this 8 1/2 lb. gun could have felt that light but I think this talks to what you are discussing.

Bingo, builder !!!!!
Best,
John

Balance is a separate thing to "pointability". I supect that often the two are used interchangeably when they're not.
Pointability is that quality you get with a gun where the weight is not just balanced but concentrated between the hands by light barrels and stocking, and is very much to do with inertia. That's why guns with the same overall weight and dimensions can still feel so vitally different - one can be a nearly living wand which dances surely to the shoulder and chases targets of its own volition, and another a lump of 4x2.
RG

From my research, we need four numbers to sum up a gun's dynamics, its handling fingerprint, if you will. Weight is the most fundamental parameter. It determines the effort required to carry, lift, and hold the gun; further it determines recoil attenuation. Beyond lift, all other movement of the gun is changing the direction it is pointing.

Swing is the movement that changes the direction the gun points. The effort required for swing is measured from teeter-totter balance point and moment of inertia at the teeter-totter balance point.

Teeter-totter balance, along with hand placement, tells you how much of the gun's weight is carried by each hand. I measure from the balance point to the (front) trigger because the trigger is the one point on the gun you must touch to shoot. The balance to trigger measurement allows comparisons of all types of guns, even those that don't have hinge pins. You can use any point of reference you want, but you will always come back to relating the balance point to hand placement if you are going to do anything with it. There is no perfect balance point, only personal preference.

The amount of muscle effort needed to make the gun swing when held between the hands is measured by moment of inertia at the balance point. MOI is a measure of weight distribution. When the gun is mounted to the shoulder, the swing axis can be considered to be the butt and can be calculated. Preference for swing is purely a personal decision; some like wands and others pigs on snow shovels.

So, if we know weight, balance point, swing effort at the balance point and swing effort at the butt we pretty well know how the gun handles. Trying to tell someone else what handling fingerprint he should like or use is much like telling what stock fit dimensions he should use. Shooters must realize that what they shoot best and what they enjoy shooting most may well be two entirely different things.

Thank you all so very much for enlightening me on this subject. I really appreciate it.

I hope everyone on the board has a Happy Thanksgiving & Good Hunting!

Hairy

There is an excellent article in Gough Thomas book "Shotguns and cartridges" on gun balance.
He refers to it as a guns "moment of Inertia" and actually measures it on a cradle to come up with a figure.

GDU

GDU - balance and moment of inertia are different things. Balance is the point where the gun stays level teeter-totter fashion when placed across an edge or round fulcrum. I reference it to the (front trigger) as the best point to make direct comparisons from gun to gun; not the only reference point possible, but the best. Moment of inertia is a different attribute and I measure it with a small machine I have constructed.

Weight is a measure of effort to lift and hold. Balance is a measure of how the effort is divided between the two hands. Moment of inertia is a measure of the effort required to swing the gun.