Bought one of the first Weaver T16's (all they made in target scopes was the T16) way back. The carbide balls cannot deform under the pressures that steel ball bearing start to deform. They wear less. I've owned the T16 for 30+ years and it is still very repeatable. I have a USA made 4-12 AO Weaver w/ Micro Trac, same story. A USA-made Micro Trac 1 1/2 X 20 is on my Ruger #3 in 45/70. The recoil is brutal (400gr @ 2100fps in 6 1/2 lb rifle). The scope rings and scope mounts have worked loose once after many rounds even though they were installed with Red Loctite. Scope adjustments are still top notch accurate. Surviving the Ruger #3 was the convincing test.