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

Lads,
I saw a thread over on SSM, it was about the "Circle" jointing (that's Jointing :)) method.


It mentioned the bbl chamber end /breech face angle as being 90*.?
I was thinking, if two parts are mated perfectly,like a perfectly jointed gun, as in showing no gap, at a perfect 90* angle to the water table/flats,then the bbls could not rotate up & open, as there is no clearance for the bottom/extractor end of the bbls..?
I believe I have read that the angle is usually more "open", at the Top?
So am I mental, or just a bit thick,lol
franc(ly) curious,
cheers

2 or 3 degrees 87 or 88 not 90

It may matter where the pivot point is.

Webley machined their actions 87.5 degrees .

The hinge on a normal break action double is well below the water table. consequently as the barrels start to open Everything on the breech end above the hinge line, certainly includes all above the table, moves forward. I believe that 87.5� stated for the Webly means the standing breech is actually tipped forward not to the rear.

You are correct miller. Rich

You know fellers, when really getting in the nuances of double guns I am amazed at the complexity of design, even on the simplest.

If you took a line from the center of the hinge pin to the juncture of the watertable & standing breech then a line perpendicular to this line would be tangent to the circle of rotation, thus the gun would open & close if cut to this angle.
Just grabbing one gun at random & taking a rough scale measurement I got about 2� from the center of the hinge to the standing breech & about a 7/16" from from the water table to the hinge center. Using trig to find the angle from the hinge center to the base of the standing breech gives about 11�. While this much forward angle to the standing breech would certainly not be desirable the gun Would Open even if perfectly jointed.

I'd think the reference line might be the bore and not the water table. I'd suspect the standing breech and back of the barrel meet at near 90* to the bore. Possibly, the angle that's smaller than 90* has its corner at the hinge with one line perpendicular to the bore and the other touching the bottom breech end of the barrel/extractor.

If the standing breech were at an angle other than ninety degrees to the bore, and it looked like it were on face, I don't think the shell would drop in and sit flush. Containing the case head might be suspect also.

its not 90 degrees to the bore, get a square put it on the water table and check the breech of the barrels there will be a gap at the top of the square.