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American Handgunner Jan/Feb 2010 - Page 67
ForCiNG CoNe TooLs HAMiLToN s. BoweN MANsoN reAMers Forcing cone and chamfering reamers and the spot facing cutter, all with removable pilots, make revolver barrel work easy. wheel Gun wonders e very now and again, a tool comes along that will revolutionize a process, however obscure or seemingly unimportant. While great forcing cone reaming tools are not essential to life on the planet, those that work well are a great comfort to those who use them even casually, let alone on a daily basis. Dave Manson of Manson Precision Reamers has brought professional pistolsmiths and hobbyist alike a set of tools which represent a quantum leap forward. Revolver barrels have a bevel at their mouth, just forward of the cylinder muzzle, commonly called a “forcing cone.” The object of this modest conical cut is to conduct the bullet into the rifling with minimal shaving and deformation and often spells the difference between an accurate revolver and a “Wanted” poster tack hammer. Vintage revolvers often had nothing more than a 45- to 60-degree chamfer which didn’t help much. Then, a bulb glimmered in some sharp lad’s mind and he saw that a longer, gentler bevel angle to get bullets into the barrel with less damage would be much better. Over time, most revolver manufacturers settled on an angle of about 11-degrees, and all was right with the world. From time to time, gunsmiths and revolver builders will need to cut, or re-cut, forcing cones. Relic revolvers with forcing bevels need the treatment to get them to behave. Later guns may have steeper cone angles and can be improved upon. Heavily used guns may have burned or otherwise damaged cones which need to be renewed. Newly installed barrels often need to have the existing proper forcing cone deepened to the correct diameter. Custommade barrels just need a cone, period. Until now, this exercise was often fraught with frustration due to existing tool design. The traditional forcing cone cutter was threaded to accept a T-handle driving tool. Pilot bushings, such as they were, went on the driving tool shaft. Fit to the shaft was sloppy with the bushing OD a one-size-fitsnothing-well diameter. Often as not, the cutter and driving tool threads weren’t coaxial. Tooling was often too sloppy to true up a crooked, eccentric forcing cone as the cutter just Closely fitted pilot bushings help minimize chatter and make for a smooth cut. Below: The T-handle driving shaft has a spring-loaded centering guide and pre-load collar to help keep the cutters in line. Very nifty. But Why? followed the loopy existing cut. Poor bushing-to-barrel fit caused chattering in the cutting which resulted in a rough, chewy finish that caused leading and unkind commentary. Dogs And Cats? The Manson Precision Reamers tool solves all of these problems at a stroke with its proprietary design. Not only is the pilot bushing on the cutter itself — for perfect alignment between cutter and bushing — the bushings themselves are Continued on page 78 67 WWW.AMERICANHANDGUNNER.COM