Strange sizing issue

[Weldor]

I just had a weird experience with just 2 -6.5 PRC Hornady cases. Sizing die left set from last year, sized 100 cases and ran them through my lyman case gauge. 2 are not fitting. I annealled them and tried again same. re-set the die nothing still same. Anyone seen this before? I'll probably just toss them since they chamber hard. but just 2 out of 100 ? RCBS re-sizing die Coaxial press.

 

[onlybrowning]

How many firings on the cases?

 

[Weldor]

2 this would be the 3rd ..

 

[onlybrowning]

I'm not familiar with the Lyman case gauge. My suggestion would be to take a piece of brass that chambers as it should and start measuring (and recording) it in various places with your calipers and compare it to the two pieces of brass that do not chamber as well. Start with the overall length, then measure the rim, the web, and the diameter of the outside of the neck. You can also color some of the case with a marker and see if you see anything obvious when you size it or try chambering it.

 

[Weldor]

Thanks, all case's trimmed to same length. The case gauge is basically a saami chamber. The shoulder bump seems to be the problem. Springback was my first thought but only 2 case's? Going to see if I can get some data for the shoulder when I get back to the house Thursday. Thanks.

 

[xsn10s]

If you're using an expander ball that can stretch cases slightly while being extracted. I polish mine if they are rough. If you polish measure the diameter before and while polishing.

 

[TaperPin]

Sharpie the surface of the brass on the cases that won’t chamber and it will show where the tight spot is.

 

[Dos XX]

Measure the .200 line, right above the extractor groove. Compare to ones that do chamber. Your die might not be sizing enough, and those are the first two to expand enough to matter. If so, the rest will follow with more firings.

6.5 PRC chambers are known to be tighter than a normal sizing die will handle.

 

[Dmoua]

Not sure why you need a case gauge if you’re sizing the brass to your chamber. Measure a few pieces of brass that fits your chamber and compare it to the two that don’t and see where the difference is.