I'm reloading for a .223 and have a Redding FL neck die set to bump the shoulder 0.0015 so that I don't overwork the brass. The brass is Starline that has been fired in the chamber and reloaded a few times. I have a stainless pin tumbler that I use to clean the brass. It is decapped and then cleaned. This time after cleaning I ran it all through an annealing process on an annealer that I made. (that works great by the way) After I annealed the brass I ran it through the pin tumbler again so it would stay nice and shiny.

I decided to try a box of Hornady 73 grain ELD-Match bullets so I measure the distance to the lands and loaded one up then tried to chamber it and it would not go. The bolt stayed open as if I had a No-Go gauge in the chamber! Thinking maybe I got the numbers on the distance to the lands wrong I seated the bullet another 30 thousands deeper and tried again and it still would not allow the bolt to close. I chambered an empty case from the lot that I had cleaned and annealed and it worked fine. I loaded bullets into five more resized cases without powder and primer and none of them would let the bolt close.

Running my finger over the cleaned cases I discovered a slight lip on the edge of the case mouth. It was visible when held at just the right angle. Thinking that was unusual I ran a case by my chamfering tool and seated a bullet and voila, the round chambered no problem! To verify I took one of the previous cases that would not chamber with a bullet seated and I pulled the bullet, chamfered the case mouth, reseated the bullet and it too chambered no problem.

An internet search turned up the following info: https://www.varmintal.com/arelo.htm

Scroll down to the sections on "Neck Mouth" and "Polishing Brass". It seems that pin tumbling brass beats the case mouth and can, and does, cause a lip to form on the case mouth inside and out and can work harden the case mouth. (so much for annealing) I don't know if that means that I let the brass tumble for too long or if the Starline brass is softer than the other brass that I use.

I thought this was interesting and posted to let those interested know.