doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com making heavy barrels lighter

One of the most interesting posts that I have seen regarding doubles was placed on Shotgunworld, by Shotgunguru July 16, 2012.
It explained the concept of achieving optimal game gun balance when weight was concentrated at the action. He discussed how to weigh the gun components individually. It is something you should read.

Don Amos, Rocketman, has been acquainted with this concept for many years. He is the one who explained it to me when he spun a double of mine years ago on his turntable. When he explained the importance of where the mass is concentrated on doubles, and how that affected handling, it was just as if a light came on for me. Its all very simple, but if you've never thought through it all you don't really understand how two 6# guns can handle so much differently. I had read an article about Don and his MOI measuring device earlier in Shooting Sportsman but still didn't get it until we talked.

I agree that everyone who has any interest in how a doublegun handles should make the effort to understand that concept. BTW, having a large part of the mass concentrated in the action is not always what makes for good handling. It can be just the opposite, as I learned. I have a very lightweight .410 S x S with 28" barrels that I shoot well. I couldn't understand how that could be, as the majority of shotgun shells I go through are in a 9 lb. 3 oz. Perazzi. When he showed me how the mass is concentrated at the butt and in the barrels, and with the lightweight alloy receiver, I understood. With more of the mass being on the "ends" of the gun it slows it down a bit. He actually said that the turntable numbers on it were almost identical to a good English 12 ga. game gun.

SRH

volleyfire, with all due respect and no offense intended, I'd take exception to said article's precept. First, there is no such thing as an "optimal" characteristic for a gun. There will be one or more sets of characteristics that are optimal for one given shooter. As an example, there is no one optimal set of stock dimensions. Each shooter has his own. So it is for handling, no one universal set of optimal characteristics; each shooter will have his own.

Second, handling is characterized with weight, balance (the teeter-totter definition), unmounted swing effort, and mounted swing effort. It is impossible to "sum-up" handling with one characteristic. Length of pull does not define a stock. Likewise, balance does not define handling; it takes all four of the above.

Third, the term "balance" is often misused in an attempt to sum up handling. Subjective explanations are always suspect since two shooters would have to be "calibrated" to each other's subjective words to gain truly accurate information. For example, "This gun has perfect stock dimensions!" Perfect for who? "This gun has perfect balance!" Perfect for who? Is the reference to teeter-totter balance or to the subjective summative definition?

Stan gave a very good explanation; he truly "gets it." I'm just fleshing it out a bit. Fourth, if the weight were truly concentrated at the balance point the gun would require zero effort to swing unmounted and less than usual mounted. This is certainly not desirable, much less perfect/optimal.

Post back to discuss or for clarification.

DDA

Don, you just keep making it more difficult for me to poke at you but here's a try.

You might want to replace " balance (the teeter-totter definition)" with "weight distribution" since all the bean brains already have internalized "balance" albeit in a likely misguided way, and apply their misconception to your better (maybe) methodology.

I applaud your move to a no absolutes position. And there are even no absolutes for an individual. Different horses different courses etc.

have another day

Gee, WTS, I'll take that as a compliment. ;-) I appreciate your humor and try to return it.

Balance (teeter-totter) is the summation of weight and distribution; weight times distance from the point where weight times distance on each side is equal. "Weight distribution" by itself is a wee bit open to interpretation.

+1 on "horses for courses."

If there was an optimum for any of the characteristics of guns (weight, balance, swing effort, LOP, drop, cast, pitch, barrel length, forearm size/shape, grip size/shape, etc.) then there would only be that number/size/shape in use as everyone would shoot it best. If all of the characteristics had optimums, there would be only one standard gun and we would all never miss. There is a rumor that WTS bought the prototype of this gun at great cost and has selfishly hidden it away. ;-)

DDA

Don,

I cannot tell you how happy I am to find out that you are the originator of this concept. As you could tell from the questions I asked, it was apparent that the idea was one of importance that I could appreciate but not fully understand from the information given. It could not be truer that everyone needs and wants a gun with a slightly different set-up. But I would very much appreciate you summarizing the principle, either here or in a private message.
Thanks Stan.

Steve

Rocketman is our current guru, but Gough Thomas had something to do with it...

Say not sure if this helps but in reviewing a post on guns on pegs 2017 a short clip on a barrel maker making sxs barrels from a single billet claimed stronger and lighter replacement barrels may be worth a quick search
Rich.

Volleyfire, following is a short explanation of handling.

Stock dimensions fit the gun to the shooter�s physique. Handling fits it to his strength, muscle speed, hand placement preference, and shooting style. As we use differing stock dimensions for differing shooting situations, so do we use differing handling. The objective of any fit is to better adapt the gun to the individual shooter. Better fit may result in higher scores and/or more fun.

Weight, balance, unmounted and mounted swings are the four dimensions of handling. Swing is the dimension that tells us the effort needed and/or time required to point the gun in a differing direction. Moment of inertia is the measurement that tells us swing effort. MOI at balance point is for unmounted swing effort and MOI at butt is for mounted.

MOI measures the resistance of an object to changing rotational velocity. The gun resists starting swinging proportional to its MOI. It resists stopping swinging likewise. Increasing MOI indicates increasing effort to start swing and stop swing.

Following are three examples of averages:
Average 2"-12 Bore Game Gun weight = 5.37#, balance = 3 5/8 " to trigger, unmounted swing = 0.95, mounted swing = 4.75, gauge = 12-2", avg bbl length = 26, avg LOP = 14 1/2"

Average Game Gun 6.50#, 4 1/2", 1.45, 6.38, 12-2 1/2", 28, 14 1/4

Average Light Pigeon/High Pheasant 7.21#, 4 5/8", 1.67, 7.46, 12-2 3/4", 29", 14 3/4"

MOI at balance is measured on a constant torque turn-table driven by a bob-weight. The gun is clamped in a vise atop the turn-table. One revolution is timed and MOI calculated via an engineering formula. MOI at butt can then be calculated via the parallel axis theorem.

Questions?

DDA

Thomas and I were/are afflicted with two of the same maladies - mechanical engineering and an obsession with guns. Thomas published his work with a torsional pendulum in the 1960's. I never heard of him or his work until I started posting data in the late 1990's. In the resulting firestorm,someone pointed out, in my support, that Thomas had published this same sort of work. Thomas was disappointed that so few Brits were interested in the technology of guns and shooting. He did only a few guns to satisfy himself. So, I confess to following in his footsteps, but with a greatly expanded data base and broadened application.

MOI machines are calibrated with "bars" of calculated MOI.

DDA