K&M BULLET TENSION EXP MANDREL 8mm, -.0020BT Markdown

When using an expand mandrel to achieve final neck sizing bullet tension K&M find it best to size your neck 0.002 to 0.003 below your desired final bullet tension size. For example, say you are working with a 7mm caliber (0.284) and you would like 0.004 of bullet tension. Subtract the 0.004 from the standard bullet diameter, 0.284-0.004=0.280, this will be the final size after expanding. However, the neck inside diameter needs to be slightly smaller so the expand mandrel can properly size the brass. Now subtract the 0.002 or 0.003 from the final size, 0.280-0.003=0.277. Now based on your neck wall thickness select the appropriate bushing that will achieve the 0.277 inside neck diameter. Once this sizing is complete perform the final sizing of the neck with the expand mandrel. Be sure to at least use a light lubricant. Alternatively, you can use a traditional full-length die (expander ball removed) and use the expand mandrel for final sizing.