Burrard wrote he felt it was a mistake to have barrels of different length fitted to the same gun as Barrel Flip would cause them to hit to a different point "Vertically". He did not confine this to sub-bores but was speaking primarily of the 12 gauge, which was at the time of his writing "THE" gauge in the UK.
Could you please quote Burrard on muzzle flip. I think you and Joe are using "Muzzle Flip" when you mean "muzzle rise". "Muzzle flip" is a dynamic by which the barrels bend downward from the initial recoil, and shoot low. Garwood wrote of this phenomenon and that is how I remember he described it. He said that long barreled sub bores were more susceptible to it because the barrels were not as stiff along in the vertical plane since they were of a smaller diameter. I would dig it out of Garwood's books but since I am debating several of you I am at a time disadvantage. So I request the favor a you, asking you to dig out Burrad's definition of muzzle flip.
At any rate when I used the phrase of "muzzle flip" I meant it in the meaning I described above.
Now let me Speculate a bit. I believe it is a False Assumption to believe that the barrels of every given length, every weight of gun & every load fired has to end with the same degree of convergence. Maybe I am misinterpreting here Mike but I seem to be getting the feeling you are saying this has to be so.
By definition all Parker two-frames have to have the same distance between the centerline of the bores at the breech. By definition the muzzles touch on all Parkers. The amount of convergence needed in any barrel set is determined by the MOI of the gun (everything else being equal). Suppose I make a shotgun out of carbon fiber and aluminum with identical dimensions to a 26" Parker two frame. I mean same stock dimensions, same spacing of the bore centerlines at the breech and at the muzzle. Suppose when I get done building it it has half the MOI of the real Parker two-frame 26". That carbon fiber gun will need much more convergence than the real Parker because, as the shot goes down the barrel, the barrels will rotate much more before the shot leaves the barrel because the carbon fiber gun has a much lower MOI. If the carbon fiber gun had the same convergence as the real Parker AND the tubes were straight the carbon fiber gun's right barrel would shoot way to the right of Joe's dove perched on the barbwire. The left barrel would shoot way left. But wait a minute! I can't give that straight barreled carbon fiber gun more convergence because the barrels will cross each other at the muzzle. So, instead of putting the bananas back to back I turn each banana over and they curve out from each other in the middle but join at the muzzle and breech. The muzzle end has a higher convergence than straight barrels and the carbon fiber gun can shoot straight.
Miller I make the same request of you that I made of Stan. I request that for just a little while we keep the discussion on two-frame Parkers. By doing that I think we can broaden our areas of agreement and gain a more exact understanding of our differences. Or course it is up to you.
I have gone back & re-read your link to the Parker Board. Let me say this as kindly as I can, but I can see absolutely nothing there other than the speculation that barrels of different lengths having the same breech spacing & still touching at the muzzle "Must" have been bent so the last section of the barrels at the muzzle would have the same convergence. This is as far as I can see an unproven hypothesis.
I go back to the lamp. The light is not piped in through a fiber optics cable. Electrons going through wires to the filament cause it to emit photons. I have never seen an electron. No body else has either. But we have to have electrons to explain the physics of our world. I certainly am not offended by your statement. We are arguing facts and physics. I would much appreciate a more detailed explanation of your disagreement with my Parker post.
In studying the history of barrel making one finds their configurations were Set, well back in the Welded barrel era. At this point a barrel was generally made to be round at any point, though contoured down its length. Metal for the flats was welded on. It was also found that flats needed to be put on the mating surfaces of the breech ends of the two barrels to bring their centers closer together, else they would indeed crossfire. Of all the barrels I have ever checked this on I still find that the web between the two barrels is not equal to twice the the wall thickness at the extreme breech end of the barrels, thus Gunmakers are still building to essentially the same criteria. All the writings I have seen would indicate that standard practice was to make the barrels as straight as humanly possible & to set them at a converging angle, no doubt worked out over time by trial & error. The "Very" limited amount of barrels which I have personally checked show that "Those" barrels were indeed made in this fashion.
Your belief that the tubes are always intended to be straight is the reason I keep focusing on two-frame Parkers. If you give the length of a factory orginal set of two-frame Parker barrels AND if the tubes are straight as you contend I can calculate the convergence. And it is amazing that the convergence rate and the MOI just happen to work out that those straight tube Parker two-frames shoot straight, whether they have 26", 28", 30", 32", 34" or 36" barrels.
