Expand Mandrels

Description

.22, 6mm & 6.5mm and bullet tension from .0020″ – .0035″ in .0005″ increments. (more calibers and bullet tensions coming soon or upon request).

All mandrels are compatible with our PowerStroke mandrel holder (sold separately), which fits our Press Adapter (sold separately).

Description

Expand Mandrels for Bullet Tension:

After selecting the caliber, select each bullet tension expand mandrel desired for your kit.  Each selection allows for selecting an etched press adapter and the corresponding gage pin for that neck tension.  Both the expand mandrel and the press adapter are laser-etched with the caliber and the bullet tension for easy identification.  The gage pin block will be etched with the caliber and each gage pin location will be noted with the bullet tension and the diameter of the gage pin.  All of our expand mandrels are ground oversize to account for spring-back of brass which is assumed at the nominal anneal.

When using an expand mandrel to achieve final neck sizing bullet tension we 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.