doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Forcing cones in old doubles

Should the forcing cones be opened up on older doubles? I have heard that the old shot shells with the rolled crimp over a wad procduced a shorter over all hull than the newer pastic shot shells with the star crimp and shot cups.
I have the 12 gauge reamer to do so, and have opened up a few, but have heard conflicting stories as to whether it is required or not.
Supposedly it is suppose to reduce the pressure and help the shot pattern. What I heard was the newer shells with the star crimp, has the crimp opening partially into the forcing cone on some older shotguns.

Hi Saddlesore,
I often lengthen the forcing cones in short chambered (2.5") guns so that I can shoot 2.75" shells without damaging the shells (yes, I realize that I still have to be careful to use low pressure ammo). It seems to work just fine and according to the British proof house, does not take the gun out of proof like extending the chamber would. I'm not British and that's never been an issue, however it is comforting to know that according to one nations experts it doesn't effect the safety of the gun.
Steve

Unless the gun is some sort of super rare specimen or something I plan to "flip", I generally send barrels off to Briley if I plan to use it. I have them lengthen FC and "tweek" chokes consistent with my expected use. As suggested above, that work enables me to shoot an occaisional 3" 20ga in a M21, but I don't make it a pratice to shoot modern hot stuff in an older 2 1/2" gun.

Saddlesore, this is probably not kosher feedback. I've lengthened the forcing cones on a number of guns and have no complaints. Then, some years ago, I just got lazy and quit having the barrels altered. I shoot 2 3/4" hulls in the short chambers all the time and have never experienced any problems whatsoever. Nor did any of the oldtime gun experts, such as Gough Thomas, Burrard or Askins or any number of the old men. In fact, Parker even recommended shooting the longer hulls in their short chambered guns, feeling it provided a better gas seal. Now, I want to be perfectly clear on this: I would never shoot longer SAMI loads in a short chambered gun EVER! All of my loads produce pressures in the area of 7,000 psi or less--always! Fairly extensive testing of shooting longer shells in short chambered and short forcing cones was conducted some years ago by Sherman Bell and results were published in the Double Gun Journal. The conclusion was pressures did not increase substantially, certainly not enough to cause any concern.

The length of a shell is determined by its "Fired" length. Thus a 2 3/4" shell will be 2 3/4" or close to it, many are a little short, irregardless of crimp type applied. A loaded 2 3/4" fold/pie crimp shell is shorter than a 2 3/4" roll crimp shell. Many, but not all by any means, of the older roll crimp shells were 2 5/8" length. Some years back I fell into the long cone theory & lengthened a few, But Never Again will I do this to an old classic. Most of the advantages of the long cone were simply dreamed up to sell reamers & cone jobs.

I have limited experience with this but recently did the forcing cones in a double to improve the patterns. When I reamed the cones I took notice that the chambers were quite tight, almost cutting a completely new one and then lengthened the cones out to 1.5" from .5". When tested the patterns only slightly improved (less than 5%). What I did notice was a reduction in recoil, which some claim that forcing cone work helps and others say it does nothing for recoil. In this case it did. I would do this modification again, it was cheap and easy and made the gun more pleasureable to shoot.

I wouldn't do it.

I've never saw that it improved the pattern...might even make it worse.

I just settled on buying and reloading Short Shells.

I just stopped buying them with short chambers (or modified forcing cones).

"IF" it reduces recoil it does so at the expense of velocity as the payload has not changed. Personally I never felt a reduced recoil on the ones I did. The same effect can of course be acheived by simply reducing the powder charge if you reload, or buying a lighter loaded shell if you don't.