In my experience in shotgun work,
dealing with average customers who are looking for an
improvement to their favorite old smoke pole, the
screw-in choke tube is the most requested alteration. The
least (almost never) requested alteration to the shotgun
barrel is the lengthening of the forcing cone. I make
it a habit to check the forcing cone on each barrel that
comes in to see if it has been lengthened. If not, I
always mention to the customer the advantages of
lengthening the forcing cone. In the majority of cases,
the customer doesn't know what the forcing cone is or
doesn't understand its function. Here we will explain
the forcing cone, what it does and how it can be modified
to improve the performance of the shotgun.
First, let's cover The Shotgun Choke.
As any shotgunner knows, the choke at the end of the shotgun barrel determines the size and density of the pattern that the shot will produce. Different types of hunting require different shot sizes and choke patterns, depending on the size of the game and the general range of the target
In the past, hunters had the option of either buying a different barrel for each choke constriction (Full, Modified, Improved Cylinder, etc.) or having an adjustable Polychoke type device attached to the end of their barrel. Most shotguns coming out of the factories today are equipped with screw-in shotgun choke tubes which screw inside the end of the threaded barrel. This gives the hunter/trap/skeet shooter the ability to change the choke of the barrel by simply screwing out one choke and screwing in another. No more need to buy multiple barrels. All that is needed is an assortment of choke tubes which can easily be changed in less than a minute when conditions require it.
There are thousands of shotguns out there with plain barrels that can be threaded to accept the new screw-in choke tubes for less than the price of one new barrel. Once your barrel is threaded to accept choke tubes, you will have the ability to pursue any type of game that you may be interested in. Your newly threaded barrel will accept flush lead shot choke tubes, extended length steel shot choke tubes, extended length, extremely tight turkey choke tubes, ported choke tubes in every configuration, Sporting Clays tubes which are extended length with the external portion being knurled for quicker installation and removal, and rifled slug tubes, to name a few. Pretty much anything you want to hunt, you will now be able to hunt with one shotgun.
The Mysterious Forcing Cone
The forcing cone is the constriction at the end of the chamber that forces the load down from chamber size to the size of your shotgun bore. If you hold the barrel up and look through it from the chamber end, the forcing cone will appear as an abrupt ring. Most barrels come from the factory with this abrupt ring, or forcing cone.
When the shotgun is fired, the shot load is immediately FORCED, under tremendous pressure, to squeeze through the abrupt forcing cone to the smaller size of the bore. This results in some of the lead shot becoming deformed, making them ballistically unsound and causing them to fly out of the pattern. Lengthening the forcing cone removes this abrupt constriction and allows the shot to make a more gradual transition from chamber to bore size, reducing shot deformity and allowing more of the shot to remain in the pattern. The combination of the screw-in choke tube and the long forcing cone can turn an old shotgun into a much better performer with considerable improvement in pattern density and versatility.
By the way, I take great pains in putting the finest polish possible on the forcing cone after I have lengthened it, a step many overlook or rush through. The fact is that the polishing step is half the job when done correctly. A rough, unpolished forcing cone is a magnet for plastic wadding and residue accumulation, which in turn attracts moisture and causes rust. It also, obviously, makes it harder for the load to pass smoothly through the forcing cone to the bore.
I have had many barrels sent in that already had long forcing cones but were unpolished. Customers tell me that cleaning and maintenance is greatly reduced with the polished forcing cone, and I have even had reports that the pattern density has improved with the polished forcing cone. I've never made that claim, but it is feedback from customers.
When the forcing cone polishing is done correctly, you should be able to run a tight patch down your barrel from the chamber end, through the forcing cone and down the bore, and never feel any difference in resistance except that the inside diameter gets smaller. If you feel a rough, snagging like resistance when the patch passes through the forcing cone then your forcing cone needs to be polished. Try the tight patch test and see how your barrel feels.When I am finished, your forcing cone will be long AND smooth. Very Important!
Take a look inside your barrel. Odds are, if it's a regular production shotgun it has a short, abrupt forcing cone. On the other hand, take a look inside an expensive trap gun/ skeet gun, most guns out of the factory custom shops, or the guns that are winning the turkey shoots/splatter shoots/ card shoots, and you will see a nice, long forcing cone. This tells us something!
I often encourage customers to pattern their shotgun before they bring it to me and then again after I lengthen and polish the forcing cone. The results have been positive, with improvements in pattern configuration and gains in pattern density of up to 12%. Simply put, you get more holes in a 30 inch circle at 40 yards with a long polished forcing cone than you do with a short, abrupt forcing cone. For the last 15 years my customers have agreed!
An Obversation:
Since I put up this web page I have been surprised at some of the forcing cone work I have seen. Some are chewed up by chatter and many have been lengthened but barely polished or not polished At All! The polishing process is half the job. In addition to complete bore and chamber polishing, I offer the forcing cone polishing service for forcing cones that have already been lengthened but were never properly polished or were never polished at all.
