Would you use them ?

[Bruce Day]

It won’t make a bit of difference. I’ve used both for many years in both fluid steel and Damascus guns.

What will make a practical difference is the powder and shot load in the cartridge, not the length of the hull.

[Randy Roberts]

If it's a hunting gun you can consider lengthening the chambers thus removing all the concerns over pressure as it pertains to shell length that you may have shooting ammunition that your gun was not designed to shoot.

[C.O.B.]

Originally Posted by Randy G Roberts

If it's a hunting gun you can consider lengthening the chambers thus removing all the concerns over pressure as it pertains to shell length that you may have shooting ammunition that your gun was not designed to shoot.

With all do respect to Randy NO DON'T DO THIS
The easy and simple anser is just shoot the 2 1/2 shell the gun was designed for. All I shoot are 2 1/2 from 12 down to 410. Never been a disadvantage.

[Randy Roberts]

It's concerning how many times I have spoken to Gunsmiths concerning lengthening chambers and this conversation or information has never came up. Most recently with a fellow who is well known around the PGCA world if you will. I had the chambers lengthened a few years ago on a Sterly 20 and that's it to date. Duly noted and good info Gents !

[Bill Anderson]

Think about this ... I am sure that the time between the production of most old SxSs and the birth of collector associations and forums on the internet, bringing these concerns to light, most of the guns we get our hands on today were shot with any shotshells that were available at the time, maybe 100s, 1000s of times without even thinking of chamber length or age of the gun. If someone bought an old Fox in 1982, for example, they would simply go to the gun store in their neighborhood or K-Mart and buy any shotshell they wanted for what they were going to hunt.

Bill

[Bill Murphy]

Todd's comment about tapering the junction from the forcing cone to the bore got me thinking. Tapering the junction from the forcing cone to the bore is actually "lengthening the forcing cone". By the way, how much encroachment into the forcing cone is experienced in the first 1/4 inch of the forcing cone? I would rather have the extra metal than 150 psi less pressure.

[todd allen]

Originally Posted by Bill Murphy

Todd's comment about tapering the junction from the forcing cone to the bore got me thinking. Tapering the junction from the forcing cone to the bore is actually "lengthening the forcing cone". By the way, how much encroachment into the forcing cone is experienced in the first 1/4 inch of the forcing cone? I would rather have the extra metal than 150 psi less pressure.

Yes. "Lengthening the forcing cones" is what the procedure is called.
The gun is a 6 lb 5 oz 12 gauge, with 30" bbls, that came with 2 1/2" chambers.
Lengthening the forcing cones lowers the pressure, without weakening the chamber area.