doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Hands on a real cutie

Couple of hours ago I got an invitation to lay hands on one that is "'bout as cute as a spekled pup." So, I just naturally had to give her a spin.

The cutie here is a Churchill SLE XXV Premier Quality Skeet model!!! Made for and shot by a lady, too. 5# 2 1/2 oz, 3 5/8" balance (teeter-totter to front trigger), unmounted swing effort of 0.86, mounted swing effort of 4.16, and a half weight radius of 8.80. Barrels are 2# 2 1/2 oz and 25" long, LOP is 13 5/8", and OAL is 40 1/2". Short, light, and fast!! Tied for second place in the MOI database with a Gibbs .410 BLE and behind a NEA Pardner Youth model .410. Greased lightning!!

"unmounted swing effort of 0.86, mounted swing effort of 4.16, and a half weight radius of 8.80"

OK...I am far too stupid to know what any of this means. But I suspect somebody somewhere got a gold star on his forehead for figuring out how to make something very simple very complicated!

Rocketman? Or Rocket Science?

GSY - unmounted swing effort tells you how much effort is required to make the gun point in a different direction (swing) while held between the hands. Mounted swing effort is th the effort required to make the gun point in a different direction when it is mounted to your shoulder. Half weight radius is a measure of compactness. The average for game guns in my database is 6 1/2# weight, 4 1/2" balance, 1.45 unmounted swing, 6.38 mounted, and 10.17 HWR. The Churchill above is 1# 5 1/2 oz lighter, balances 7/8" closer to the trigger hand, takes about 2/3 the effort to swing of a the average game gun, and is very compact.

The MOI machine is to swing what a yardstick is to stock fit, a scale is to weight, and a fulcrum is to balance.

I think you are way "too far from stupid" to not be able to learn these numbers. Too stuborn might be a different issue - we can discuss that if you want ---.

I have imagined the following conversation the first time a yardstick salesman sayshsheyed in to 'Ole Billy Moore's gun shop, "YARDSTICKS? We don't need no stinking yardsticks!!! Stocks are too long, too short, or jezrat! Why would I want to know how long it is??"

OK, Rocket, where do these figures fit when one shooter is 12" taller than another , and they hold the gun in different places ?

Daryl they don't. There is no formula to say how well a gun swings or doesn't. Each person has to pick it up and test it to their satisfaction.

Once you establish the numbers you either shoot well or enjoy shooting (these are not necessarily the same thing), you can "know from afar" if you will like a gun or not; just as you know if a stock can be made to fit you from hearing/reading the LOP. Also, you can nearly replicate a gun - think making a "pair" when the time and place of manufacture are widely separated. Not knowing these numbers for yourself is to handling like not having your stock dimensions is to fit.

A gun with swing effort of 1.0 takes half as much effort to swing as one with a swing effort of 2.0.

But what does the square root of the angle of the dangle work our to be? (Commonly referred to as counter-cast, or shooter compensation for shooting a gun with the opposite cast he or she requires?) Sounds like a "20 day vaction for 2 or a 40-day vacation for 1" type exercise. Forget all this nonsense and SHOOT the things!!! KBM

Rocket,
I would like to know more. How are the measurements made and what calculations are done. Can anyone determine a "swing effort?"
Jake

Jake - I have devised and built a simple little machine that "spins" the gun on a horizontal turntable for one timed revolution under constant torque (bob weight drive with the drive line on the turntable perimeter). Moment of inertia is easily calculated from known torque (bob weight's weight times turntable radius), known angular movement (one revolution) and known time (stopwatch). Calibration is done with an assortment of steel and aluminum bars of measured size and calculated MOI; my cal is pretty acurate (R squared of 0.9998 for those interested in such things).

I multiply the actual MOI times ten to get typically whole numbers and decimals for guns and call it swing effort. There are other ways. Actually, Tom Hammernick showed that you could get useful data with a shoestring and a stopwatch (torsional penduleum principle).

I have a database with 386 guns (as of this afternoon) that I share with anyone interested. Anyone wishing to do his own work can contact me for assistance. I have built 6 machines (2 loaners). See Sept-oct 2001 Shooting Sportsman for an article on this.

BTW - I have gotten a lot more knots on my head than gold stars over this subject. Fortunately, I have a very hard head and thick skin. Questions are always welcome.

That Churchill was one of those guns that just screams, "Buy me, buy me!! I'm so cute you must buy me!" But, i know better!! An unmounted swing of 1.2 is about my legal limit for either fun or good shooting. I don't need one more gun I can't shoot well, no matter how cute. After all, I keep reminding myself that I can't afford to run a gun museum. But, it sure was cute, tucked into a deminuitive toe-under case that just fit

Well...OK. But I am a firm believer in the adjustability of the human body, which is why I don't let a gun's dimensions bother me. I allow myself a box of shells to get used to the gun - any target I miss after that, it's my fault, not the gun's.

I am curious, though....you are stranded on a desert island, and a beat up lifeboat floats up with Jennifer Aniston, Faith Hill, and Shelby Lynne on board. Their clothes are ripped to shreds, they are cold, and are starved - starved for sex.

Do you tell Ms. Lynne and Hill to get back on the boat and start rowing because their swing radius and bob weight is a little off your optimum setting? Or do you say, "Hell ladies, perpare for blastoff! They don't call call me Rocketman fer nothin'!".

Maybe for rabbits in the briar patch!
The 25s seem to have this anti-gravity thing going for them.
So, they've fallen out of favor.
We are shooting sporting birds, not life ending metors speeding through space.

Couple of questions:
Unmounted swing effort, what is the axis of rotation? Is it the balance point, or is the gun assumed to be held part way out from the body?

Mounted swing effort, what is the axis of rotation (the butt?)? When the gun is shouldered it seems to nearly enough rotate about the butt. The real axis may be somewhere in the shooter's body.

Balance point - self evident, except how to reference.

Half weight radius - is it measured from the balance point? Do you put your hands on the gun so that half the weight is between them?

Overall weight - self evident.

Do gun makers use the MOI quantities? Obviously, some practical understanding of weight distrubution with or without the numbers has been used by makers.

And what gauge (er, bore) would this cutie be? Sounds about right for a 28.

I have seen this idea discussed before, but haven't seen anyone try to quantify it so scientifically. I think the idea has merit.
I have two guns with almost the same dimensions and weight; they both fit me well, yet one handles like a lump of 4x2, the other positively dances between the hands because the weight is concentrated between the hands by light, skilfully struck barrels and stock boring.
I wonder whether being able to quantify this so accurately takes away some of the magic of picking up a gun and just "knowing" it's right though?
RG

I'd say you need a real life, outside your basement laboratory. After all your effort your database is unpublishable because every firearms researcher knows that summary results have to be accurate to the fifth decimal place, weight in ounces must be stated to the nearest 1/64th of an ounce, and linear measurements to the closest 1/128th of an inch. Your scale is obviously not electronic NIH laboratory research grade, and your yardstick must definitely be pre-May 5, 1937.

Dave - if it ain't your thing, then just move on.

I've enjoyed Don's SSM articles and had the pleasure to meet him and swing a few of my guns at the Southern SxS. Although working through what Don's numbers are telling me brings back painful memories of a college Dynamics course 20 year ago, it is intersting stuff - for some of us. If it ain't your cup of tea, fine, but bashing the guy and his work is out of line.

Ken

The Tom Hammernick shoestring and stopwatch (torsional pendulem principle) method that Rocketman referred to earlier first shows up in print (to my knowledge) in "Shotguns & Cartridges for Game and Clays" by Gough Thomas pages 161-164.
Gough Thomas Garwood, M.SC, C.ENG., F.I.C.E, F.I.E.E. He was a working "chartered civil engineer" (back cover bio) who had an interest in "things shotgun" and an ability to write. Glad I got the multiple copies (mine and gifts) of his books on eBay years ago as they have become very scarce and pricey.
On pages 161 - 164 GT discusses balance, Figure 82 shows the shoestring and stopwatch method, Moment of Inertia (MOI) and how to calculate it and in Tables 12 and 13 gives data on Best Guns and then Other Guns.
Rocketman's apparatus is a modernized tool to measure MOI and has value if you learn the comparative language. And as Rocketman clearly pointed his MOI figures are "data" just as LOP, DAC, & DAH are "data".
MOI is an academically interesting "nice to have" once you have the gun in hand and quantifies why one gun feels like a "bridge-timber" and another, a "wand". The only serious problem I see with this MOI data is that virtually NIL gun sellers have it for their guns on offer....and maybe the vendor thinks that's a good thing if he's trying to move a "bridge-timber".
My $0.02 FWIW.

It is people like Rocketman who help us to grow in our understanding of why guns "feel" like they do. I am most appreciative of this "scientific" approach to the balance and feel of guns. I held in my hands today two guns which were stocked almost identically. Both 12 gauge, both 30" barrels both by British makers a Scott sidelock from 1910 or so the other a William Evans Boxlock. In spite of the appeal of the sidelock I can tell you that it is the boxlock that I would choose over the two. Why? Both were well balanced as to centre of gravity, both weighed 6 lbs 12 ozs. Both were well stocked with DAC and DAH and Cast just about identical but the Evans was just that little bit better in "feel". Rocketman has opened a window to objective evaluation which although we choose not to jump through it is well worth the look. Maybe one day purveyors of fine arms will include MOI and other pertinent information which could assist us better in appraising a guns suitability for us from afar. Just my pennys worth.

Don's contributions here are always interesting, well researched, polite and respectful. His 'life' is scientific research, one subject is shotguns. Most of us enjoy reading and learning more on that particular topic. Don's work attempts to quantify the previously unquantified. Note that most pioneers in any field are subjected to ridicule... only after their contributions have proven worthy, do they receive acclaim.

Don reached the status of valued scientist here before most users of this system had even registered. Bash him at your own risk, you won't win many friends.

PS: I'd like to shoot a round of skeet with that gun... just to attempt to control the uncontrollable!

Credit is due D.A. for several "educational" efforts here; program for getting objectifiable results from patterning (which he will share with you), the "tier system" for valuation of British game guns (which he will share with you), and the terminology and test apparati of gun dynamics (which he is trying to share with you). Don has actually spent considerable time here trying to make some of us addlepated bumpkins THINK. I'm not much at physics or math but the acronyms MOI and HWR have a clear objective reality to me and, I'd hope, to anyone who has held a well-struck and balanced doublegun.

jack

I had the pleasure of having dinner with Don "Researcher" not so long ago. I can tell you that Don is passionate about bringing objective technical rationale to this community. We will all be educated from his efforts. Don is another of the many great contributors here and this particular effort of his is one of his great passions that only confirm his standing with many of us here.

Dave Noreen has that one patented, Chuck.

jack

None is so blind as he that would not see.

Sometimes a cigar is just a cigar.

GSY - it would be "Blastoff!" I shoot a variety of guns. I adapt to differing stock dimensions, to differing handling dimensions and to differing aesthetic stimuli. I am currently logging the results of shooting these differing guns. Stock dimensions are, of course, easy to measure (there goes that 'ole yardstick). Handling, to me anyway, is easy to measure. Aesthetics is still a mystery, but I know it is there. The good news is that I can easily share results that include stock dimensions and handling dimensions. Handling will not depend on my subjective judgement of the guns, rather it will be objective data for one and all.

JH - the gun will swing naturally about the balance point (center of gravity/CG/teeter totter point) unless some effort is expened to force it to do otherwise. The lowest swing effort will always be about the balance point. Shooters with differing prefered hand spread and differing physiques may well swing the gun differently, but the characteristic of the gun itself is at the balance point.

Mounted swing is calculated (from LOP, weight, and MOI at balance point) for the butt. I agree that the true axis is somewhere within the shooter's body, but we do get a useful characteristic by this calculation. BTW, this calculation is based on the parallel axis theorum which says we can calculate MOI about any axis.

Balance can be referenced to any point you choose. The (front) triggger is the mose useful and simplest. Balance tells you how the weight of the gun is proportioned between your two hands. Your back hand is always positioned to pull the trigger. So, we know the dimensional relationship between your back hand and the gun. Measure your personally prefered hand spread and you have all the information needed to calculate weight proportioning. Any other reference point will involve more measurements. Since hinge pin to hand and breech face to hand are not fixed, comparing guns becomes more difficult if they are used for the reference.

Half Weight Radius is simply a numerical statement of compactness. 10 to 11 is pretty average for most guns. Under 10 is more compact weight and over 11 is pretty dispersed weight. Direct comparisons require the guns' weight be similar. HWR has no value in telling you where to place your hands - do what you feel is natural for you or what a coach tells you.

The Ruger GL got its handling from referncing the handling properties of a Dixon RA, including MOI. Many gunmakers do MOI intuitively. Some are starting to pay attention to the possibilities of owner adjusted handling.

Cadet - I believe in magic. But, like the Conn Yankee of Mark Twain's imigination, some magic takes a little preparation. IMO, the magic happens when a shooter finds/has made a gun with accurate fit to his stock dimensions, handling properties that suit him best, and aesthetics that really hit his hot button.

DM - my life is very, very real. This is some of what I do for fun. I can measure to any required accuracy. However, I actually measure to those accuracies that are practical for this project. Parts of my database are published and other parts will be. At this point, it is a freebie for those interested.

DS - did I forget to mentiion this cutie is a 20 bore/gage/gauge/guage??

And, thanks to many for their kind words and support.

I know one thing for fact about XXV's-they are a bit hard on a 'feller's ears.

You wouldn't think 4 or 5 inches of barrel steel out there on the ends of the tubes would matter much....but, it does. Don, I have a 20 gauge Darne with 29 1/2" tubes, and a semi-pistol grip stock, that weighs but 5 lbs, 12 ozs that it would be interesting to see strapped into your tilt-a-whirl. I plan on it being my dotterage gun, if you will.
Best,
Ted

Ted, I have the following 28 bore Darn in the databasc, but no 20 bore. You can draw some idea from this. Light and fast!! Yours will be about this weight, but the longer barrels will slow it down a bit - maybe enough to make it managable with a deft touch.


Darne V-19 sliding breech, 5.69# weight, 2 1/2" balance, 0.93 unmounted swing, 4.37 mounted swing, 28 gauge, 25 3/4" barrel length, 14 1/4" LOP, 8.71 HWR

Stick to your guns Rocketman!

Rocketman and I often find we are discussing the same issue and approaching it from very different angles. However, we generally find that we come to the same conclusion. His science tells me what my experience would tell me were I there (but one cannot always be there).

I was sceptical in the tier system for valuation, but experience has led me to be at first interested and then respectful.

I think this MOI investigation based on the new machine is an avenue that deserves more work and look forward to more of Rocketman's findings as time goes by.

BTW, I love Churchill XXV Premieres. I have shot well with them when I have used one (all on live game)and the quality and handling go hand in hand......and I usually shoot with 30" barreled hammer guns.

Don,
Well, if you are really interested, comparing V and R grade guns is about like comparing apples and oreos. A V gun is more petite in the action, and will always weigh less in the middle than the same gauge R does, without wood.
There are no parts that interchange between an R and a V, the lockup is different, the cocking and firing is different, they dismantle differently, and they are usually built of two different kinds of steel. But, they 'kinda look similar.
We have to tie my R down someday, just to see how much, and if they differ in MOI. Every good double gun is an individual, it seems like to me.
Best,
Ted

These things are undervalued gems.
Most folks will not even try one, fine by me.

The only interesting sheep are the black ones.

Being the first to wade out into the swamp is sure to get you criticism, but when its successful you will also be the first to reach the other side.

I'll throw my hat in w/Rabbit for realization that not all of us are well struck nor balanced and Dig for a more readily understandable validation of your efforts to qualify certain aspects of dynamics, i.e., making them less fuzzy;-)

A very big THANKS for that!

Blaser F3 barrels within a type (game, sporting, trap) weigh the same for any length. So, 28" - 32" sporting barrels all weigh the same. Assuming the balance adjustment system in the stock is not changed, I would guess that a 2" change in barrel length would make a very small change in either measured or subjective MOI. A 4" jump would be more evident. If the barrels flare out to take the choke tubes, then the muzzles would be relatively heavy, and the change in feel with length more apparent. If the Blaser has been tested with different barrel lengths in place, I would like to know how it fared.

A PBS program on Stradavarias covered efforts to understand why they are so good and to match their sound. People tried and fell short until a physics professor, if I recall, figured out the critical elements and could make and adjust violins to sound like Stradavarias. Hope for those who need a fine violin to play or practice, but cannot afford a Stradavarias.