Chamber / Forcing cone

[todd allen]

Originally Posted by John Dallas

There's no "Proof" in the US.

I was referencing the H&H in the post. It came to me with 2 1/2" chambers. Briley's recommended tapering, as opposed to lengthening the forcing cones.
They told me that tapering the cones would not weaken the chambers.

[stumpstalker]

Yes, how does one taper further what is already tapered without removing the material involved?

My crude rendering here of what I understand of Parker gun barrels (as per THE PARKER STORY and Larry Del Grego and Son).

[Drew Hause]

Because the angle of the cone exceeds the angle of the external taper of the barrel, there is more wall thickness within the cone than the end of the chamber.
The cone can be lengthened (BY AN EXPERT, who is removing metal) while maintaining a wall thickness equal to the end of the chamber

Courtesy of Hollowell



Lengthened chamber with the blacked in portions being the metal removed in the process.
Upper side shows a 5 degree angle to the cone. Lower side shows the cone cut parallel with
the outer wall yielding a cone length of approximately 1 1/2".
Courtesy of Miller Fulks as posted on DoubleGunBBS



This is a cross-section of a chamber lengthened from 2 5/8" to slightly longer than 2 3/4".



This MAY NOT APPLY to small gauge or light weight British 2 1/2" chamber game guns.

Bottom line IMHO is a 12g No. 2 frame "shooter" Trojan with a 2 5/8" chamber could safely have the cone lengthened by an expert.
I'm not aware of any benefit in doing so.
I would NOT mess with the chamber or cones of a short chamber 20g.