MANSON REAMERS FORCING CONE TOOLS

Wheel Gun Wonders
41

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Every 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.

Forcing cone and chamfering reamers and the spot facing cutter,
all with removable pilots, make revolver barrel work easy.

But Why?

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. Custom-made 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-fits-nothing-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 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.

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.

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 removable and available in a variety of diameters in .0005″ increments. In addition to the piloted cutter, the driving handle has a nylon centering cone held in place at the muzzle by a spring. The sliding pre-load collar makes accommodating different barrel lengths and setting centering tension to your liking a snap. With perfect cutter alignment and bushing fit, the results are startling. Smooth, concentric forcing cones are child’s play. Even dogs and cats could use this tool. Okay, even dogs could, I can’t promise about the cat part.

In addition to the basic 11-degree cone cutter, Manson can supply a 45-degree chamfering cutter to break the inside edge of the newly cut cone, which will keep this edge from burning away under the high heat and pressure. The available 90-degree facing tool is helpful in cutting away the final few thousandths of an inch when installing barrels or opening up barrel-to-cylinder gaps.

The two 11-degree cone and two 45-degree bevel cutters will handle calibers from .357 to .50. The four 90-degree facing cutters will cover virtually all known revolver barrel-shank diameters. Within each caliber, there are several bushings to get the best barrel fit. A set of pin gages in .0005″ increments through the usual range of bore diameters will be helpful in ordering the right one. Just bear in mind to check at the breech end of the barrels since many barrels are set hard and have a slight constriction. Individual cutter prices start at $48 and bushings are $12 each. The cutter handle with centering guide is $24.

Forcing cones should be cut within a fairly narrow range of mouth diameters. The general rule of thumb is guns that range well probably should have shorter, smaller cones since unnecessarily long cones afford more opportunity for propellant gases to devour bullet lube and soften the exposed sides of bullets better to solder-up your bore. If the gun ranges well, a shorter cone will work. Check with Brownells or Midway for range rods and cone gauges.

After using this tool the first time, I can now tackle this simple every day job without fear and trepidation. The real test is whether or not the elves will use it if we leave it out on the workbench overnight. Cross your fingers.

For more info: Manson Precision Reamers, www.mansonreamers.com, (810) 953-0732,; Brownells, (800) 741-0015, www.brownells.com; Midway USA, (800) 243-3220, www.midwayusa.com

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