doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Angle of the Break Off...waterT & standing Breech?

Obviously, considering a oblate spheroid planet, you're going to need more than a simple square to measure that radial angle to the curved surface of the water table - allowing of course for fluctuations in the level of the water table itself and the instantaneous position of the standing breech relative to it.

HTH

have a day

Dr.WtS

Whisky Tango Foxtrot?

The basic reference in shotgun design is the imaginary line of the bore axis. The breech is indeed at right angles to the bore axis. It is NOT 90 degrees to the water table, by definition it cannot be. Since the barrel breech ends are conical it follows that the water table and breech which fit the barrels form an angle smaller than 90 degrees.

Amazing how many experienced gunsmiths assume that the breech-water table angle is 90 degrees, when a little thought shows it just cannot be so.

Though the barrels assembly is static and apparently simple, it is not. Just try and draft a pair of barrels and you will discover just how complicated things get, ie convergence, alignment on the horizontal plane, firing pin distance, the ejector leg hole location and the metal thickness between that and the chambers, a whole bunch of parameters jump out at you.

One of the most complicated projects for me was the fitting of monobloc barrels onto an action designed for chopper lumps. The two methods of construction differ at critical points and it is a headache to get it all correct.

That is correct On the Webley action it was the last machine operation an angled side and face finishing cutter was used to create the face angle ,radius and finish the action flats . Previously the action had been cut at 90 degrees as this was a datum face for other machine operations .I can not comment on other makers but I would assume they would be similar.

Well of course the Standing Breech "CAN" be cut 90� to the water table. The barrels will ordinarily have additional metal on their bottom which is cut "Flat" to mate with the action flats. I have never actually measured to see if it was or not but this could well be cut parallel with the bore axis. What is ordinarily done & what "Can" be done is often entirely different things.

Wonko;
The simple act of imagining a line perpendicular to the line joining the center of rotation to the juncture of the table & standing breech was not intended in any way to show how a double gun was constructed, but simply was to show that one so constructed "Would open". "IF" you would like to show your Superior Intelligence then Prove Me Wrong otherwise as far as I am concerned you can Cram It.
This whole thread generated from the misunderstanding that as the hinge on an ordinary SxS double is below any point on the breech of the barrels those points are upon opening moving Both up & forward. That point of tangency to the circle of rotation taken at the lowest point of the parts in rotation then determines the Maximum angle the breech could be cut to & still be operable. Certainly that angle would never be cut to such a great extent, that was not the point.

sorry Rodger, i was giving a simple answer to your question.mc

Great gawd! Wanko called the receiver flats a water table; and I never thought of the verticle face being anything other then 90 degrees. Obviously that won't work. I guess even the hardest head can learn if he hangs around here long enough. Thanks gang.

Most of the British manufacturers will put between 88.5-88.8 degrees between the breech face and the flats.The face leans forward at the top.The breech face of the barrels is 90 degrees to the centre line of the bores.This ensures that the cartridges sit squarely against the action face.

You cut the standing breech to 90 degrees then you must add so much metal to the front underside of the chamber area of the barrels you end up with a metal cudgel, not a shotgun. Not to mention that the cross pin center is moved in relation to the barrel axis and all kinds of interesting phenomena, especially angle of recoil, will start to materialise.

Try drawing such an arrangement on paper, it will be educational.

I was referring to the geophysical water table not the action flats of a gun.

"Angle of recoil"??? Was this covered in a special class at Hogwarts? I can hardly wait to hear the synopsis.

have a day

Dr.WtS