308 Cartridge gauge

[snooker]

I purchased a Hornady cartridge gauge, first one I've ever owned. Always used the barrel of my bolt actions for adjusting the sizing die. Figured I would use it for a Stag 10 in 308 win. I'm using brand new dillon carbide dies in 308 win. I sized 100 cases after adjusting the size die using this gauge. 96 cases are perfect for headspace, below the top of the gauge and at the minimum slot of the gauge. I have 4 cases that sit proud in the case gauge. No adjustments were made to the sizing die once the initial settings were complete. These 4 cases I have sized a second, third and 4th time ( again with no adjustment to the die). They still sit proud in the gauge. The cases (all 100) are all FC 18 headstamped Scratching my head. Whats happening with these 4 cases?

Dave.

 

[M1-Garand]

Same thing has happened to me in the past until I figured out that is was caused by an ejector dimple in the rim of the case.
To verify that put the case in backwards,rim first,and see if it hangs up,if it does trim the base.

 

[snooker]

Put the case in rim first, it goes in but is canted, not plumb. Thanks! The problem is at the "tail' end and not the "business end"! Makes sense.

 

[bigedp51]

Case gauges vary in diameter and many of these gauges are at the SAAMI max diameter.

Below is a "FIRED" Lake City 7.62 case in a Dillon case gauge and the case diameter is preventing the case from dropping all the way into the gauge.

Below is the same fired case in a JP Enterprise case gauge that is closer to SAAMI minimum diameter. Meaning if the resized case drops all the way into the gauge the cartridge will fit in any chamber.

Below is a Hornady cartridge case headspace gauge and you "CAN" measure a "FIRED" case and adjust your die for the minimum amount of shoulder bump.

The "FIRED" case below was measured and then the die was adjusted for .003 shoulder bump for my AR15. Meaning most drop in case gauges will not tell you how long the fired case is and you are guessing on how much to bump the case shoulder back. And the Hornady gauge can be used with all calibers and you do not need to buy a case gauge for each cartridge.

 

[snooker]

Thanks bigedp51.