I’ve had TKC cut several cylinders for me as an active USPSA and ICORE competitor. I shoot steel challenge RFPO exclusively with 617 with TKC components. TKC does great work, with tremendous customer service, and quick turn around. I’m hard on my equipment and their components (triggers, firing pins, springs) are top notch. If you’re a serious revolver shooter TKC is the best in the business.