Description
The 338 RPM puts belted-magnum performance into a standard short-action-length Mark V, and the Weatherby 338 WBY RPM 185gr Barnes TTSX is the load that makes the most of it: the lightest bullet Weatherby offers in the cartridge, driven fastest.
- What the RPM Case Was Built to Do
- Weatherby 338 WBY RPM 185gr Barnes TTSX Specifications
- Honest Notes on This Load
What the RPM Case Was Built to Do
Weatherby introduced the Rebated Precision Magnum family to get magnum ballistics out of a rifle that does not need a magnum-length action. The 338 RPM uses a rebated rim so a standard bolt face handles a fatter case body, and the result is a 33 caliber cartridge that delivers close to 338 Winchester Magnum performance in a lighter, shorter rifle.
The Weatherby 338 WBY RPM 185gr Barnes TTSX is the fast end of that cartridge. At 3100 feet per second with 3947 foot-pounds at the muzzle, it shoots flat enough that a 300 yard zero keeps you inside vital-zone holds well past 400, which is not something most 33 caliber hunters are used to.
Weatherby loads this in Sheridan, Wyoming, as part of the Select Plus line. The 185 grain Barnes TTSX at this velocity produces recoil noticeably softer than a 225 or 250 grain 338 load, which matters in the lightweight Backcountry and 307 rifles this cartridge was designed around.
Weatherby 338 WBY RPM 185gr Barnes TTSX Specifications
The Barnes TTSX is turned from solid copper with no lead core, so there is nothing to separate. On impact the polymer tip drives back and the nose splits into four petals that peel outward while the shank keeps its diameter and drives forward. Weight retention is typically close to 100 percent, which is what a monolithic buys you.
Because there is no lead, the Weatherby 338 WBY RPM 185gr Barnes TTSX is legal wherever non-toxic ammunition is required, California included. That is worth confirming before a hunt rather than at the check station.
The one caveat with any copper monolithic is expansion velocity. Petals need roughly 1900 to 2000 feet per second to open reliably. Starting at 3100 that threshold sits past 500 yards for this load, so it is not a practical limitation for hunting, but it does mean this is not the bullet for a deliberately slow or reduced load.
- Cartridge: 338 WBY RPM, Rebated Precision Magnum
- Bullet weight: 185 grain
- Bullet type: Barnes TTSX monolithic copper boat tail, polymer tip
- Muzzle velocity: 3100 feet per second
- Muzzle energy: 3947 foot-pounds
- G1 ballistic coefficient: 0.432
- Lead free: yes
- Case: brass, boxer primed, reloadable
- Series: Weatherby Select Plus
- Rounds per box: 20
- Manufacturer part number: B338185TTSX
- UPC: 747115447268
Honest Notes on This Load
Buy the Weatherby 338 WBY RPM 185gr Barnes TTSX if you hunt elk, moose or bear with a 338 RPM and want the flattest trajectory the cartridge offers with a bullet that will not come apart. It is also the load to buy where lead ammunition is restricted.
Step up to the 225 grain TTSX if your shots are close and heavy shoulder bone is likely, or if you want more retained energy past 400 yards. The heavier bullet starts slower at 2800 feet per second but carries better downrange.
Two honest cautions. Copper monolithics almost always print to a different point of impact than lead-core ammunition, so re-zero rather than assuming. And 338 RPM ammunition is proprietary to Weatherby with limited factory options, so buy enough for the season when you find it.
Heavier option in the same cartridge: the 338 WBY RPM 225gr Barnes TTSX, or the lead-core 338 WBY RPM 225gr Hornady InterLock. The Weatherby 307 Adventure SD in 338 RPM is a rifle built for it. Weatherby publishes complete Select Plus ballistics charts on its own site.
MAG5 Firearms stocks Weatherby Select Plus ammunition and the Mark V and 307 rifles chambered for the RPM cartridges. Ask about lead-free requirements for your hunt area before you order.
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