I had an experience that is unusual in my 40 years of reloading I thought I’d relate.

A couple of decades ago I bought a bag of 500 of once shot 5.56X45 Lake City brass with head stamps of 87 and 92. I full length sized and loaded 200 of them with different loads for accuracy checks and sight in.

After selecting the best load for the rifle (a TCR 83), I NECK SIZED and loaded 150 of them for a prairie dog shoot. The load used H380 powder and Federal 200 small rifle primers. This was in 1995.

In addition to the 5.56/223 barrel I took a 22-250 barrel and loads and ditto with a 243 barrel for the shoot. When a barrel got too hot, I would switch to another barrel and rotated through the 3 barrels throughout the shoot. After the shoot I shelved the leftover 5.56/223 loads in my ammo safe. There were 33 rounds left in one box and 50 in another of the 5.56/223’s.

For further P-dog shoots I stayed with the 22-250 and 243’s (2 of the 243’s) and the 223 barrel stayed in a safe. As time went on, I sold the 223 barrel to another TCR collector while the leftover loads of that day in 1995 stayed in my ammo safe.

I didn’t have a 223/5.56 rifle for 20 years but recently found a new TC Compass II rifle for sale that called my name. So, I rummaged through my ammo safe and found those leftover 2 boxes from 1995. I found that they would not chamber in the new Compass II rifle.

So, pulled bullets and discarded the old powder.

I then lubed and started to full length size the brass. I started with the 33 brass from the one box. 18 of the 33 resulted in split necks. In going through the remaining 50 I had 13 of them split out of the 50. So, I decided to discard all of this brass as too much of a possible risk. I noticed most that split were marked 87 (1987) on the head stamp.

I still had the remaining 350 of the brass that had never been used in my stash. After cleaning I took a random sample of 75 of those through full length sizing with no failure or splits.

It remains to be seen if the splits will happen after I shoot these 75 rounds and reload them. Or, if the loaded rounds sitting in the ammo safe for 25 years had some cocktail reaction that degraded the brass.

I have had other caliber loads (of commercial brass) that were leftovers hang around the ammo safe for up to 10 years (or so) before being shot and reloaded but only those 83 have sat that length of time and have had such failures.

FWIW - Ken