doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Let's Play Spin the Parker

Maybe Don will give us a review and let us know how these figures fit on a chart of "whippy" to "sluggish". I guess we need a full explanation of all four ratings and how they fit on the chart by number.

What's it all mean Mista Natural?


Just kidding. Don shared his MOI spreadsheet with me a while back and I happily realized that my preferred gun dynamics (big and piggy) fit my budget (low).

Thank you one and all for your responses. Gun handling/dynamics has traditionally been a subjective field. The numbers give you an objective option. I've no quarrel with those who are satisfied with subjectve understanding. I'm trying to provide an option for those who would prefer objective measures. Certainly, I've no intent to prositylize those wishing to deal only with subjective measures.

The handling numbers are to handling as stock dimensions are to gun fit. Gun dynamics is a muscle exercise on the human end. Therefore, we need information as to how much muscle effort handling the gun is going to require. Dynamically, the gun can be lifted and it can be rotated. And that is it in terms of what the human has to do to point the gun in the most beneficial direction. Humans are far to individualistic for there to be much of a "right" and "wrong" in gun handling. Also, consider that fit and handling can inprove either shooting performance or shooting fun, or both.


Weight is the measure of muscle effort needed to lift, hold, and carry a gun. Low weight requires less effort. High weight reduces recoil for any given load. Selected weight must optimize between these two requirements and base off the strength and endurance of the shooter.

Balance, along with individual hand placement, determines how much of the gun's weight is held by which hand. The hand closer to the balance point (teeter totter point) carries more of the weight. To determine this number, simply place the gun across your extended first finger, adjust until it stays level, marke the location over the middle of your finger, and measure the distance to the (front) trigger. You can be more accurate with a fulcrum edge for the teeter totter point. measure a few guns to see what you like best or shoot best.

Moment of inertia is a measure of the effort needed to accelerate the swing of the gun. If you wish to change the direction the gun is pointing, you must swing it. It take muscle effort to do so. Higher numbers take more effort and lower numbers less effort. On the other hand, the higher number guns will be less inclined to slow down or change direction if you let off the swing effort. For example, the 12 ga 34" #2 frame will require almost double the muscle effort to swing between the hands as will the 16 ga #0 frame gun; 2.4 vs 1.3. Once mounted to the shoulder, the 16 gauge can be swung with 2/3 the muscle effort of the 12 ga #2 34"; 6.49 vs 9.95. It will be easier to change the direction ansd speed of pointing the 16 gauge. The 12 gauge will be smoother, less inclined to inadvertent speed and directional changes. For most people, the 16 would be better suited to "snap" shooting and the 12 to tracking with sustained lead. While guns this different may be obvious, the numbers allow you to consider guns inbetween. Fugidaboud the dimensions of MOI - just compare the numbers.

Half weight radius is a measure of the guns compactness. Guns with a HWR less than 10 are compact. HWR's of 10 to 11 ate typical. HRW's over 11 indicate a gun with some significant weight in the stock and muzzle side of the barrels. Guns of the same weight can have differing HWR (why we can make useful gun to gun comparisons) and guns of differing weight can have the same HWR (weight is distributed similarly).

What questions do you all have?

Don, you've done some good work there based on what Gough Thomas suggested. But the responses are indicative of the problem with your system: 1. Most people don't understand it; and 2. Most people think they can find out what you've told them via the "feel" of the gun between their hands. Your system would be helpful if a) Everyone understood it; and b) Dealers had a device with which they could measure those factors and then include them in the descriptions they post on their lists of guns for sale.

But we ain't there yet.

LB, i think you are quite correct. The advantage I have over GT is internet access and a whole bunch of afficanodos willing to exchange information, share ideas, and ask questions. What is missing in the explainations? Did anyone learn anything from the posted numbers?

It is one thing to stand side by side with another person and discuss a gun in hand. It is quite another to discuss a gun you have never seen with someone you don't actually know via corrispondence. There was a time, not so long ago, when the numbers of stock dimensions were quite mysterious; now, many can spout them off. For those interested, the same can be done with handling. "It weighs 7# even," is a lot more useful than, "It isn't too heavy." 'It balances 4 1/2" from the front trigger," is more useful than, "The balance is near the hinge pin." "It has a unmounted swing of 2.4 and a mounted swing of 9.95," is more useful than, "it is a pig on a snow shovel."

Also, using some objective measures helps move subjective apprasials toward descriptive and away from judgemental.

Rocketman, your system is fun. I still cannot think how it might apply to all shooters, since shooters come in all sizes and hold guns differently. What is felt by one fellow, is not necessarilly felt by a fellow of a different size, who grips the gun differently.

Am I missunderstanding ?

I am interested in this and someday the info may become as common as listing an LOP, but that would require an easier way to determine the numbers. LOP just takes a ruler.

I was under the assumption that balance point should actually be measured from breech face rather than trigger, am I wrong?

Rocketman, thanks for the detailed explanation. When I have more time (and I'm not working) I'd love to send you the weight and dimensions of an ultra-light 16 gauge I own to put some numbers to.
Steve

Rocketman wrote a very detailed article in SSM Sept/Oct 2001 ("Measuring MOI") in which he explains the process in detail and what the numbers mean, replete with charts, pics and graphs. I would sure like to see an updated "kinder, gentler" version for dum-dums like myself, however.

Lets consider an average Brit pattern game gun; 12 gauge, 28" barrels, 14 1/4" LOP. It will weigh 6 1/2#, balance 4 1/2" in front of the front triger, swing unmounted at 1.45, swing mounted at 6.38, and have a half weight radius of 10.17. It will have these numbers no matter who holds it. Differing people will have differing interpertations/reactions to these numbers, but the gun and the numbers do not change. Exactly the same situation exists with stock dimensions - shooters must develop individual sets of dimensions for optimal stock fit. But, a 14 1/2" LOP is a 14 1/2" LOP no matter who is holding the gun or how he feels about it.

How to use this? Lets say we have a seller and a buyer far enough apart that travel to see the gun is not practical and the gun is of moderate value. The seller says he wants a 6 1/2# game gun, expecting to get a gun very like the above average game gun. The seller sends him a used AyA M-52 that weighs 6# 9 oz and balances at 4 1/2" to the front trigger. The buyer is unhappy. Why? Because the gun has an unmounted swing of 1.67 and mounted swing of 7.05 - the buyer was expecting a "faster" swinging gun. Had the buyer's expectations been discussed further and in numbers, the seller could have sent a Dickson BLE at 6# 8 oz, 4 3/8" balance, 1.50 unmounted, and 6.76 mounted; much more likely to suit the buyer's handling expectations.

Perfect stock dimensions and perfect balance are judgements. Unless you are correlated to the person doing the judging, such pronouncements are meaningless.