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| The least of the penalties you will pay for exploring these exciting new levels of chamber presure will include enhanced recoil to: (A) loosen your dental tillings; and, (B) develop a life-long flinch. Deformed pellets, perhaps 30% or 40% of the load, created by the "bottle neck" effect are cartwheeling off somewhere in space, as much of a threat to your dog, as to the departing target. Repeated use of adult ammunition in adolescent chambers will permanently damage a gun without corresponding benefit to the shooter. Murphy’s Law Repealed Brownells, Inc. publishes a copyrighted guideline for gunsmiths entitled: MEASURING & RECHAMBERING SHOTGUN CHAMBERS that defines the problem. The following is quoted with permission: Prior to around 1900, shotgun chamber lengths varied considerably from manufacturer to manufacturer, often resulting in odd fractions. After 1900, shotguns have been produced in the following common chamber lengths:
The Shotgun Shell In Relation To Chamber Length An unfired 20 gauge 3" shell measures 2.68" in length, which allows it to easily enter the 20 gauge 2-3/4" chamber (2.75"). However, when the 3" shell is fired the case unfolds to its full 3" length. The extra .25" of case body enters the forcing cone creating a `bottle neck’ effect through which the shot and wad must pass. "’Bottle Neck’ effect is when the end of the fired shell enters the forcing cone, thus squeezing and deforming the shot (left) as opposed to a correct length chamber (right) in which the fired case does not enter the forcing cone. Dotted line is the beginning of the bore and the end of the forcing cone." Checking and lengthening chamber lengths to 2-3/4" is usually an easy and inexpensive task for your gunsmith. This is a safety and common sense issue that does not have a downside, a classic "no-brainer." Older guns usually have short, about 1/2" forcing cones (a kind of funnel that channels the shot column from the chamber mouth to the barrel proper). You can check this visually by looking in your barrels from the breech end. The ring you see just ahead of the chamber is the forcing cone. Practicing your depth perception here, you can make a guess on the length of the forcing cones. Longer forcing cones will improve patterns and reduce recoil, so lengthening forcing cones to about 3/4" or 1" is generally recommended. Competition shooters like even longer forcing cones (I have 5" forcing cones on one of mine) on target guns, but the practical limit here is what size reamer your gunsmith has. A common misconception is that the "right" choke is what determines pattern, recoil and performance. Not so. It is the configuration of how all three elements, chamber length, forcing cone length and choke, work together to get the best results out of modern, star-crimped shotshells. If you are fortunate enough to own and use a gun from the Golden Age of Shotguns, or are considering the purchase of one, here are a couple more suggestions for it’s care and feeding after you’ve had the chamber length and forcing cones checked and, if necessary, lengthened: Treat your Golden Ager with the respect it deserves. Hey! One of these days when you’re that old -- you’ll wish you could function as well as that Golden Age shotgun does! | |||||||||||||||||||||||
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