The Firing Line Forums - View Single Post - Lee Case Trimmer Problems and how to set crimp

krackum · May 20, 2012, 01:47 AM

Schmitey is correct in his initial measurements. The Lee case trimmer has an outside diameter that doesn't fit in to all sized cases correctly. I have one that does the same thing. Using RCBS Carbide die sizer the case comes out with max prox diameter of .472, distal case diameter of .4665, and inside diameter of appx .448 (depending on the actual case neck thickness). The Lee sizer I purchased has an outside diameter of .447 which, if the case neck happens to be a bit thick, wont fit into the case.

What I can't figure out is why case outer diameters don't match SAAMI specifications. I at first thought it was a defective die or some anti-rust coating in the die that made it size the cases smaller than SAAMI spec. However, when I measured two different factory loads, they both came out at .472 outside diameter the whole length. SAAMI specs show a slight taper from .476 proximal to .473 distal. Anyone know why the SAAMI specs don't match with facotry ammo?

May 20, 2012, 01:47 AM	#21
krackum Junior Member Join Date: May 20, 2012 Location: Utah Posts: 7	Schmitey is correct in his initial measurements. The Lee case trimmer has an outside diameter that doesn't fit in to all sized cases correctly. I have one that does the same thing. Using RCBS Carbide die sizer the case comes out with max prox diameter of .472, distal case diameter of .4665, and inside diameter of appx .448 (depending on the actual case neck thickness). The Lee sizer I purchased has an outside diameter of .447 which, if the case neck happens to be a bit thick, wont fit into the case. What I can't figure out is why case outer diameters don't match SAAMI specifications. I at first thought it was a defective die or some anti-rust coating in the die that made it size the cases smaller than SAAMI spec. However, when I measured two different factory loads, they both came out at .472 outside diameter the whole length. SAAMI specs show a slight taper from .476 proximal to .473 distal. Anyone know why the SAAMI specs don't match with facotry ammo?