doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Gun balance.

As far as I'm concerned, a "well-balanced" shotgun is one that has good dynamics and pointability for its intended use, whether it is an 8 1/2 lb. 12 ga. SC o/u, a 7 1/2 lb. sxs-o/u for pass shooting, or a 6 1/4 lb/ sxs-o/u for grouse, woodcock, or quail, with some crossover between these. Pretty simple, actually.
JR

Don, I think some of us can use a refresher. And I expect there are some involved in the discussion that haven't heard the MOI basics previously. I believe it would be a valuable contribution.

I have always puzzled over the fixation with the hinge pin since the only thing unique about it is its easy visibility. There are long actions and short actions, and the hinge pin doesn't do a thing to define where you put either of your hands. Neither does the front of the trigger guard, for that matter. The trigger itself, yes, but that's just half the equation. Then you to just figure that the shooter places his other hand a comfortable distance out under the barrels, hinge pin be damned.

Well said, Ithaca5E. When people don't have an answer for a seemingly logical/simple question they tend to make one up. The hinge pin is kinda/sorta/about/maybe half way between the hands. The idea of center of weight (CG) being "between the hands" is hard to argue with. Somehow, that, over the years, got translated into the hinge pin. And now for the truth! We can reference the CG/balance point/teeter-totter point to any other point on guns. However, the most practical point is, indeed, the (front) trigger. If we do so, then we can easily determine how far it is from CG to center of the rear hand (most people have about 3 - 3 1/2" from the trigger to the center of hand). That is, on a typical game gun with 4 1/2" CG to trigger the CG to center of rear hand will be 7 1/2 - 8". One then measures from the CG to the center of the forward hand, for this example we can say 6". These numbers show that the weight will be proportioned into the hands as 6"/(6" + 8") = 6"/14" = 0.43 = 43% into the front hand and 57% into the rear hand. If we reference to any other point, we still have to get to the hand to CG lengths by extra measurements. The trigger is the only sure point where the gun must be touched to fire. If we stick with the trigger as reference, we are constant from gun to gun and balance can be compared. The preferred % weight in each hand is an individual shooter characteristic.

Questions.

DDA

OK, Larry, short course.

Weight determines the muscle effort expended to carry and lift and hold the gun. Teeter-totter balance determines on an individual basis the % of weight carried by each hand. MOI at teeter-totter balance determines the swing effort needed to make the gun point in a different direction while uncounted. MOI at butt determines the swing effort needed to change the direction the gun points after mounting. MOI at CG must be measured and MOI at butt can be calculated once MOI at CG is known. Balance at CG is determined with a "fulcrum" type pivot and tape measure. Weight is taken from a scale.

There is no magic "balance". Guns are static/fixed objects and do not change dynamic characteristic when in motion. The concept of a "balance" that sums the four handling characteristics is fine subjectively, but does not compute objectively. Useful information subjectively would depend on calibration between two shooters.

Most shooters will be enthralled with the handling of a British pattern game gun (6 1/2#, 4 1/2" CG to trigger, 1.45 uncounted swing effort, and 6.4 mounted swing effort). MOST PEOPLE WILL NOT SHOOT THERE BEST WITH SUCH A SET OF HANDLING CHARACTERISTICS. Most will shoot better with a unmounted swing effort of 1.8 or more and a mounted swing effort of 7.5 or more.

There is no point in harnessing yourself to a gun that requires so little swing effort that you can't easily control it (twitchy mother). Likewise, don't try to shoot a gun that requires so much swing effort that it tires you before you are done shooting (numb, to quote our British cousins).

Weight must attenuate recoil to your comfort and must not tire you prematurely.

Balance must be to your requirement. If you find yourself sliding your front hand around on the forearm after mounting, you may be sure the balance location for that gun does not suit you.

Questions?

DDA

Huh? Really?



SRH

Thanks, Stan. I was too tired to go there.

Larry, you asked on another thread about the handling of a SKB 100, as I recall. Best I have is as follows:

Ithaca SKB 280E, 20 bore/gauge, 25" barrels, 14 3/8" LOP, 6# even, 4" CG to trigger, uncounted swing effort at 1.02, mounted swing effort at 5.39, and half weight radius (compactness) at 8.88" (very compact). Does that help or do you need a different gun?

RM: All front triggers are NOT created equal. Some are further forwardt han others and vice versa. Some ST guns even have adjustable triggers. Because of this, I'm wondering if front trigger is a good reference point since they do not appear to be constant?

Gun fit is far more important than gun "balance", however you measure it. The concept of the gun balancing on the hinge pin assumes that all action have the hinge pin the same distance from the heel and barrel end. Taint so.
What seems to matter more is that the mass of the weight of the gun lie between the hands.