6.5 fails Lyman case gauge but Chambers fine in rifle

[steves86ta]

Hey guys

Stupid question time

I shoot f-class with an ar-10 in 6.5 creedmoor. I've been reloading for this for a while now and have a pretty decent recipe.

Last months match I had one round out of the 200 I brought that didn't chamber right and upon ejection I noticed the shoulder had a bulge in it. So something funky happened that I didn't catch.

For my 308 AR I obviously don't spend the same amount of time or effort loading as I do for the 6.5. But I do case gauge all the 308 with a Lyman case gauge.

So I ordered a Lyman gauge in 6.5 and figured I'd just add it as a step. Well upon spot checking some of the rounds I loaded up this week. They actually 'fail' the case gauge and remain proud of the gauge a little bit.

With my 308 id junk these, but that stuff I load for reliability and it's not really precision ammo of that makes sense

The 6.5 chambers easily and ejects easily from my rifle it just fails the gauge. I didn't check every round but out of the 100 I loaded, 15 off them all failed the gauge the same way but they all loaded fine.

I am using a Forester FL die set up to bump the shoulder .005". Hornady brass and this is it's 3rd firing. They were annealed, FL sized, trimmed, chamfered, etc.

I'm not to concerned but figured I would ask. I've only had ones failure in close to 700 rounds so far.

 

[rwj]

Case gauges may, or may not, be dimensionally the same as the chamber. Gauges sold commercially are likely made to represent the smallest chamber dimensions. Not surprising that the chamber in your barrel is slightly larger…

 

[243winxb]

shoulder had a bulge

To much crimp will bulge the shoulder. Check trim length for a to long case.

 

[jelenko]

From Wilson's webpage for their case gauge:

"measure min/max headspace and min/max case length on fired cases. Ideal for trimming and safe shoulder sizing."​

​

=> if a case is proud to the gauge, it exceeds the max SAAMI dimension.

 

[jelenko]

proud of the gauge

Is the case proud at the case mouth or case base?

Do you have any pressure signs?

 

[K22]

From Wilson's webpage for their case gauge:

"measure min/max headspace and min/max case length on fired cases. Ideal for trimming and safe shoulder sizing."​

​

=> if a case is proud to the gauge, it exceeds the max SAAMI dimension.

^^^^ this plus, I believe, if memory serves me correctly, that the sizing end of the gauge has a .005" difference between the upper and lower step. The idea is to size the case, so it fits approximately in the middle of the step. However, this applies only to chambers cut to SAAMI specs.

If you have a chamber cut to different dimensions a bump gauge and caliber will assist you in set up your die by measuring the fire case (primer removed) and setting you die to size it to the optimal fit for your rifle chamber.

While gauge like the Wilson can be used as a qualitative check for cases shot in SAMMI spec chambers, the bump gauge and caliper measurements are more precise for setting up your sizing die.