Recent problem....expanding extractor groove??

[uracowman]

I'm having a problem recently and I don't know what the issue is. I'm currently shooting a 26 inch TRG in 308 with handloads. Federal GMM brass, 178 amaz, 44.6g Varget, GMM primer.

In the past, I could easily get about 10 firings before the primer pocket got loose enough to where it wouldn't hold a primer anyone. Recently, I've been having issues placing the brass into the shellholder after the second or third firing. It takes A LOT of force to push the brass in to load a primer and it takes A LOT of force to pull it back out. A lot of the brass is so deformed that I can't even get it into the shellholder.

Upon inspecting the brass, I can physically see the fresh marks the shellholder is making on the extractor groove of the brass. This leads me to believe that either (a) the rim is deformed or (b) the extractor groove is expanding. My question is, what is causing this? I haven't changed my load since I completed load development, but issues has only recently come up in the past few months.

 

[918v]

Brass dimensions vary from lot to lot. Powder burn rates vary from lot to lot. Your load is hot. Federal brass is soft.

 

[Deadshot2]

Look for a "half-moon" mark around the perimeter of the case head. The radius will be toward the primer pocket.


This is a common occurrence with federal brass where the case head is forced into the ejector cutout in the bolt face. Caused hot loads. Can also occur if you full length size and push the shoulder back too far. Cases fired with excessive headspace and hot loads create a lot of these marks and the result is a case head that is too thick to fit the shell holder (at least in this raised area. Another cause is if the extractor ring gets "dinged" during the extraction/ejection cycle.

A lot of shooters will use a good shell holder (anything but Lee) as a gauge to check their loads for excessive pressure. Not the best for the task but it sure shows case head expansion if the load is super hot.

 

[milo 2.0]

Brass dimensions vary from lot to lot. Powder burn rates vary from lot to lot. Your load is hot. Federal brass is soft.

+1 on what this guy says.
Another thing to look for, you've been shooting this load for awhile, and it's getting warmer. Check your throat for a carbon buildup. Normal cleaning routine and you wont notice it. Leave a patch with solvent right in the throat area for a spell, judge by how your rod enters the area as to what you feel.