Out of stock
SKU: 749011715
UPC: 050806111158
The Sinclair International 17 - 338 Caliber Expander Die Body is a precision case-prep tool for handloaders who size case necks with mandrels rather than expander balls. It covers the full 17-through-338 caliber mandrel range, so a single die body can be set up for everything from a .17-caliber varmint round to a heavy .338. This is a die body for shooters chasing consistent neck tension and tight runout numbers, the kind of detail that separates plinking ammo from match-grade handloads. Mandrels are sold separately, letting you build the exact caliber coverage your loading bench needs.
This is Sinclair's Generation II design, which fully captures the mandrel inside the die so it cannot pull out during the expansion stroke. An O-ring in the die cap lets the mandrel float and self-center within the case neck, reducing the chance of pulling the neck off-axis and helping keep runout low. The body is precision machined from stainless steel with the standard 7/8"-14 thread, so it threads directly into any single-stage or turret press built to that spec. A Sinclair stainless steel split lock ring is included, letting you lock your setting and return to the same depth repeatedly. Match a caliber-specific mandrel to the body to complete the setup; the captured design keeps the mandrel aligned through each pass.
Reach for this die body when you want neck tension set by a mandrel for cleaner bullet seating and lower runout, a common step in precision and long-range loading workflows. Set it up after sizing and before charging cases, and the floating mandrel does the rest. Pair it with the right caliber mandrel, then move through powder and seating with your usual gear. Browse our full range of rifle dies, add a die body lock ring for a second press station, and check our measuring tools to verify your neck dimensions.
No. The 17 - 338 Caliber Expander Die Body is sold as the body only, with a Sinclair stainless steel split lock ring included. Mandrels are sold separately so you can configure the die for the specific caliber you are loading, anywhere from .17 through .338.
The Generation II design fully captures the mandrel inside the die so it cannot pull out during the stroke. An O-ring in the die cap lets the mandrel float and self-center in the case neck, which helps reduce runout and produce more consistent neck tension.
Yes, if your press uses the standard 7/8"-14 threaded die station. This body is machined to that common spec, so it threads into typical single-stage and turret presses built for standard reloading dies.
It sets neck tension from the inside by pushing a precision mandrel through the case neck after sizing. Many precision handloaders prefer this method over an expander ball because it can deliver lower runout and more uniform bullet grip for match-grade ammunition.
WARNING ⚠️ You must be 18 or older to purchase shotgun or rifle ammunition and 21 or older to purchase handgun ammunition and firearms. Please reference our requirements for ammunition orders to "restricted" states HERE. Always make sure you use the correct ammunition for your firearms. Ammo cannot be shipped to a PO Box. Please reference state & local laws before making a firearm or ammunition purchase.
