Ask The Instructor: Getting Reamed

Question: What is the difference between back-boring and lengthening forcing cones. Are there any other modifications that can be done to barrels to decrease the recoil?

Answer: The simplest way to reduce recoil is to switch from a 12 gauge 1-1/8 ounce shell with speeds greater than 1250, to a 1-ounce shell at a slower speed. Adding a recoil system or weight to your gun will also help. Past this, having your shotgun’s forcing cones lengthened or the barrels back-bored are two additional strategies to reduce recoil. Most experts agree that the majority of felt recoil is generated in the forcing cone, located in the tapered area inside the barrel immediately forward of the chamber. It is through here that the shot and wad must travel, transitioning from the wider diameter of the chamber into the smaller diameter of the bore. It is in this area, the forcing cone, where friction between the barrel and the wad are the greatest. The angle of taper can effect the felt recoil. In general terms, the more abrupt or shorter the area of transition, the more recoil is felt. The more elongated and therefor gradual the transition, the less the felt recoil. It is suggested, however, that lengthening the forcing cone beyond four to five inches forward of the chamber will yield little additional recoil reduction. Back-boring is essentially increasing the internal diameter of the barrel equally along the entire length of the bore. Advocates maintain that by widening the bore, you reduce the amount of friction between the wad and the inner walls of the barrel, which in turn reduces felt recoil. Opponents contend that increasing bore diameter causes gas to escape around the wad as it traverses the barrel, reducing barrel pressure and thus muzzle velocity. While there is some debate about its efficacy for recoil reduction, back-boring also reduces barrel weight by removing steel from the inside walls of the barrels. This may result in more muzzle jump and possibly a more “whippy” feel to your shotgun. If you are considering modifying your shotgun barrels to reduce recoil, consult with an expert such as Jim Eyster of Heritage Gunsmiths (OH) or Tom Wilkinson (NC).