RCBS #90314. RCBS Case Trimmers are designed to be user friendly and provide very accurate results. These shellholders are required to hold the brass cases while they are being trimmed. Works with: RCBS Trim pro, manual and power case trimmer only. Fits: .30-378 Weatherby Magnum, .338-378 Weatherby Magnum, .338 Lapua with Lapua brass, .378 Weatherby Magnum, .40-65 Shiloh-Sharps, .45-70 U.S. Government, .460 Weatherby Magnum.