Should I lengthen the chambers in my L.C. Smith 20 gauge or 16 gauge shotgun?

Before this decision should be made, several issues should be considered:

1. If your gun is of genuine “collector quality,” any alteration from factory original may substantially reduce its value.
   
   
2. It is possible that the wall thickness immediately past the chamber is inadequate for lengthening the chamber. Many of the barrels of the older shotguns have been honed out to eliminate pitting, and, hence, the barrel walls may be thin. The entire shotgun must be thoroughly inspected. These are good reasons to be sure a gunsmith with expertise on classic American double barrel shotguns does the work.
   
   
3. Using 2 3/4 inch shells in short chambers has been shown to only “slightly” raise the chamber pressure. Sherman Bell, in article titled "Finding Out for Myself" Part V "Long Shells in Short Chambers" (Double Gun Journal, Winter 2001) said that with loads that are sensible in a light 2 1/2 inch gun, he saw no dangerous pressure levels produced. He said there was no reason, related to safety, to lengthen an original 2 1/2 inch chambered gun to shoot 2 3/4 shells, as long as the pressure of the 2 3/4 inch load you use is the same as the pressure of a 2 1/2 inch load.
   
   
4. However, recoil may be significantly increased, especially in a 20 gauge 2 1/2 inch chamber if the case mouth extends into the forcing cone, or even worse, the bore. Remember that the stocks of L.C. Smith shotguns are somewhat delicate, and a cracked stock may result from more recoil.
   
   
5. Longer chambers tend to lead to the use of heavier/hotter loads. This increases recoil which cracks stocks, and increases pressure which stresses the action. Neither are good things in older guns.
   
   
6. Lots of high quality commercial 2 1/2 inch and 67 mm loads are available today, but usually are more expensive than even the 3 inch magnum shells.
   

For a more extensive discussion of this issue see Gun Talk.

Fortunately, chamber length is not a problem with Hunter Arms Co. or L.C. Smith Gun Co. 12 gauge guns, all of which had 2 3/4 inch chambers or were marked as having 3 inch chambers.