doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Gun reboring and regulating.

Miller:

When I flip the switch light comes out of the lamp. One time I investigated and discovered the wire connected to the light switch and to the lamp was solid. So the light couldn't have come from somewhere else and into the switch and then through the wire, into the bulb, and then out to my room. I did some Google research and discovered that it was electrons flowing through that wire. They go through that filament in the bulb and cause it to emit photons.

Now I have never seen an electron. Nobody else has either. So is the existence of electrons speculation or is their existence needed to explain the physics of our world? My contention of curved SxS barrels is not merely speculation.

Stan I know I am wordy but please go back and read my post #366027.

The muzzles on all Parkers touched when they left the factory. There may be some exceptions but I have never seen one.

My specification of two-frame Parker set the distance of between the firing pins and thus between the centerlines of the bores at the breech.

So in my example the distance between the bores at the muzzle were identical on the 26" and the 32". And the distance between the bores at the breech were identical because I specified the two-frame gun.

So the angle between the 26" tubes (if straight) was different than the angle between the 32" tubes (if straight).

That's a pretty big jump, Mike, to say that filing a little metal away from one side of the muzzle is the same as putting a curve in the barrels.

Just because the results are the same does not make the causes the same. He may have been just overcoming an error in the angle of convergence built into that barrel.

SRH

Exactly!

If those tubes in Coosa's gun were straight they should have been curved. If they were curved they should have been curved some more.

I am not able to see any curve in the barrels, but I'm certainly not trained to do so.

I would like to point out that all the filing was done in the last 1/4" of the barrels. I think I could move the pattern with even less than that, but it was hard to file it without going at least a 1/4" into the barrel.

Please carry on your very interesting discussion!

So, has anybody put a double shotgun in a machine rest and sent rounds down range? What did it prove? Has anybody then fired a double off a bench to verify barrel torque effect? What did it prove? Has anybody actually measured the distance between the bores in their shotgun to see if they are parallel? Don't ask me to do it, because I can't afford the tools right now without getting into trouble with She Who Must Be Obeyed. Especially on Mothers' Day eve. Inquiring (and, in my case, lazy) minds want to know.

I don't believe it's possible to say this is so. Purely on science, if the gun rotates while the shot is in the barrel a lateral force is being applied. It's not likely to exit 'straight' out of the muzzle when it clears the gun. It's supposed to continue on a tangent to the diameter of the circle the gun was rotating on when the shot exited.

I don't believe the buttplate can be taken as the center of rotation, because it is not fixed and the shot is accelerating. I'd bet the radius that the shot is rotating on increases rapidly until leaves the barrel. One way to look at it might be the recommendation to follow through or swing through a moving target. It can be more difficult pick a lead then spot shoot at it with a fixed gun.

Say I shoot a thirty inch 100% pattern, any distance, then five more shots three from each barrel. The composite measures 32 inches. I'd want to do the back flips, but now I'm to conclude that the barrels are two inches out of regulation.

Mike;
I thought I replied last night but it appears the post went astray over the Airwaves somewhere. Actually I Fail to see any point at all in a comparison of shotgun barrels to electrons Traveling down Around the perimeter of a wire. My limited research in this field does indicate that is how they travel, rather than "Through" the wires.
As to the curve in the barrels, I have offered Drawings from the L C Smith Company showing their barrels were straight & set to a predetermined convergence. The drawing cited was for 30" barrel. I further showed that if the same spacings were used for a 26" barrel then their "Static" points of impact would be changed by only 2�" or 1�" per barrel. Consider that if exactly identical loads are fired from each set of barrel ie 30" & 26". Now I do believe we are agreed that the gun is moving as the shot travels down the barrel, thus compensating for the Crossed axis in the static position. While admittedly the time of travel down the mores is extremely small I Do surely believe you would agree that barrel time in the 26" set is less than that in the 30" set.Now Here is some "Speculation' on my part. I speculate that slightly greater convergence of the shorter barrels is a necessity to compensate for the lesser barrel time of its load. How's that for Speculation??
Now further I have stated that I have measured several barrels & found them to have a simpe straight convergence. Yes I worked off the OD's & I am fully aware that bores could in fact not be perfectly concentric. However I did this checking upon acquiring that L C Smith book & wondered just how my guns compared to the Smith specs. Well every one I measured showed a convergence of between .011" to .012" per inch of length. Perfect Match to Smith (.0113") specs though none of them were built by Smith. I did then give them the "EYE" test by looking down the bores & could detect no noticeable bend. Now I fully realize you have "Greatly Insulted" my Intelligence to be able to do this with any reliability, but with 35+ years as a Machinist I developed a pretty good eye for looking at a lot of things.
I will say one more time, to date you have offered Nothing "ABSOLUTELY NOTHING" but "PURE SPECULATION" to defend you position, while I have consistently offered Facts. I can with certainty tell you not a Single double gun I own has curved barrels set with the curves Back to Back, they are simply as straight as possible to make them & set Converged.

After spending many hours watching barrel straightening at Perazzi, Piotti, Beretta and other factories I can state that barrels are straightened several times during their manufacture.

The method used is not the concentric circles but by pointing the barrel, while in the press, towards a window edge and using the shadow/light lines in the bore. It is a more accurate method than the concentric rings.

No maker has talked of "banana" bending, all of them insist on absolute straightness.

If the barrels were bent, then there would be machining and jointing issues with either chopper lump or monobloc construction. You cannot fit a bent barrel in a monobloc while having parts hot. As for chopper lump, refer to the Holland video to see the braze flow at 750 degree centigrade and the barrels straight and relaxed, held only by wires at the breech ends while the muzzles are LOOSE and outside the kiln which they would not be if they were bent.

Personal observation of dozens of unribbed barrel sets leads me to concur with 2-Piper on this one. Barrels are geometrically convergent by design and not by bending. At least in good guns they are.

Miller I never meant to insult you or your experience in any of my posts. I put great weight on the things you post here. If I disagree with one of your posts I go over it and over it in my mind. I respect you and your opinions. But I don't know anybody that I think is right about everything, including me.

I meant to challenge the assumptions that were being made by you and others as to what what degree of curve, what degree of "tolerance" you could see looking a down a barrel with a chamber, a forcing cone, a bore, and a choke. In addition to those features in almost every double bore I have measured the diameter was larger an inch downstream of the forcing cones than it was an inch upstream of the chokes.

And as far as being insulting your "third wife" analogy was acknowledged by you as being sarcastic indicating to me that you do not believe I deserve respect. When I said I didn't appreciate the sarcasm you doubled down.

I mostly enjoy the debate about this subject. But I don't know how to respond when my opponent says I have to either agree with him or insult him by not deferring to his 35 years of experience (in another field).

You still haven't pointed out why the calcs I did on the Parker thread that I linked to fifteen posts ago don't make my point. When you do that I will address the calcs on the Smith guns you did.

Certainly I should have been more tactful but I figured anybody that could post the third wife analogy would have to have a thick skin. From this sentence forward I will put much effort into being tactful. I hope I can receive the same courtesy from you but I will make the effort regardless.

In my lamp analogy I meant I discovered the light wasn't being piped in to the lamp through a hollow tube as in fiber optics. I did not mean that the electrons ran down the outside of the wire.

Certainly the time the shot spends in the 26" barrel has an effect on the rotation of the gun. But it would seem the less time the shot spent in the barrel the less the recoil and the less the rotation. The 26" barrel needs more rotation, not less.

I point out a fact against my argument. Everything else being equal, The 26" barreled Parker two-frame gun has a lower MOI than the 32" barreled Parker two-frame gun. The 26" gun would rotate faster and that could make up the additional angular rotation needed by the 26" barrels. I find it unlikely that every double that ever shot straight happened to have the perfect MOI so that the shot was sent down (or parallel to) the same line the rib was on when the shot started down the barrel. I think they were regulated in some way, perhaps by filing the chokes or the forcing cones or by bending the tubes when the barrels were assembled or a combination of the three methods.