Replacement Back Plate for PCM-2
	Quantity in Basket: None Catalog No.: PCM-P Price: $214.00 Shipping Weight: 2.00 pounds
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This is the half-moon arc steel back plate that mounts on top of the PCM-2 power cannelure machine. The space between this back plate curve and the various diameters of PCM-W cannelure wheels makes it possible to use the same machine for a wide range of bullet diameters, and to adjust the depth of the cannelure precisely. The plate mounts to the top of the cannelure machine with two hardened cap screws, which in turn pass through holes in the plate that have clearance to allow precise position of the plate in relation to the wheel. One side of the plate has an adjusting set screw to push against the right side cap screw, and determines how wide the gap or arc path can be. Another set screw at right angles to the adjustment screw locks it in place. The bullet pushes against the back plate as it passes through the arc, and the plate is held from moving away by the end of the adjustment set screw. The easy way to set up the plate for a given caliber or depth of cannelure is to determine the bullet diameter at the desired cannelure depth, and place two pins or previously cannelured bullets at the start and at the end of the arc, with the correct diameter (caliber) of wheel installed. If using previously cannelured bullets as a guide, the cannelure on the bullets must be engaged in the raised embossing ring on the cannelure wheel. Push the back plate toward the wheel so that both pins or bullets are firmly engaged by the embossing ring, thereby positioning both ends of the plate at the desired distance from the wheel. It is best if the two pins or bullets are placed about 1/2 inch inside the arc of the plate, rather than exactly at the ends. While holding firm pressure on the back of the plate, tighten both of the cap screws. If the place cannot be moved close enough to engage the pin or bullet on the right side, back off the adjustment set screw to allow this to happen. Test the setting with two or three bullets, and check the height, depth, and evenness of the cannelure ring applied to the bullets. If the bullet does not move through the track and emerge on the right end, adjust the plate position slightly by loosening the cap screws a small amount and using the adjustment set screw to move the right end to a position which provides the best and most even cannelure. Try to avoid overly-deep cannelures, as the more metal is displaced, the more likely the bullet will become oversized from displacement of additional material. Some commercial operations use only .001-.002 inch cannelures, but the average cannelure depth is closer to .010 inches. Bullet casters are used to .030 or more depth, sometimes .100-.150 inch grooves, but that is to hold lubricant. Jacketed bullets use the cannelure as a crimping area, or as identification. A much more shallow depth works fine for this.