The Hazards of Old Ammo — Watch Out for Internal Corrosion!
Above is a 26-year-old hand-loaded .300 Winchester Magnum case that failed to fire. After the misfire, the shooter used an inertial (impact) bullet puller to pull the bullet. In the process the case-neck sheared off.
Here’s a cautionary tale from the Tactical Rifle Shooters Facebook group. This real-world example explains why you should be cautious of old ammunition. Here serious internal corrosion was discovered.
Old Ammunition — Why You Should Be Careful
Commentary by Tactical Rifle Shooters
The subject often comes up as to whether it is safe to shoot old ammunition. Historically my answer has always been yes, since over the years I have shot military surplus ammo dating back to World War II (1939-1945) and never had a problem. With over 40 years in competitive shooting, I’ve also had boxes of factory ammo that were 30+ years old and all worked flawlessly.
But I had an interesting experience this week shooting some .300 Winchester Magnum (WinMag) that I had loaded for competition with Reloder 22 back in 1993. I was breaking in a new barrel so just shooting any old ammo that I had. Of the 20 rounds, 15 shot perfectly, three had a fraction of a second hang-fire, and two didn’t shoot at all.
SMART TIP: If you have old ammunition, pull one bullet to see what’s going on inside.
So I pulled the bullets using a hammer-type impact (inertial) bullet puller. What I found was verdigris-like corrosion inside the necks, with one neck completely separating. One reason for this could be that dissimilar metals (copper and brass) can set up a reaction resulting in corrosion. Like I said, this is the first time I’ve seen this, but will definitely be more aware when shooting old hand-loads in the future.
Above is one of the 26-year-old reloaded .300 WinMag cartridges which had failed to fire. To check the internal condition, the bullet was removed using an impact (inertial) bullet puller. Note the verdigris-like corrosion and crack in neck.
Here’s a close-up of the same .300 Winchester Magnum hand-load from 1993 showing serious corrosion inside the neck. (This was a fail-to-fire.) The powder was Alliant Reloder 22. If you have old ammo, it wouldn’t hurt to pull one bullet to see what’s going on inside.
CREDIT Tactical Rifle Shooters Facebook Group for this Ammo Tech Tip and photos.
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Tags: 300 Win Mag, 300 Winchester Magnum, Case Corrosion, Corrosion, Old Ammunition, Vintage Ammo
I saw something similar last summer with some mid-seventies Remington UMC .223, 55 FMJ ammo. The shooter disappeared in a cloud of smoke; when I examined the gun, the case head had ruptured. I pulled bullets from the remaining 15 or so rounds and found very similar green corrosion inside. Some had actual chunks of it, others, the entire interior wall of the case was coated with green fuzz. On the outside the ammo looked brand new.
I would until then have agreed that old ammo is OK, but obviously that’s not always true. One thing we often don’t know about old ammo is how it has been stored. Like the .223 ammo above: was it in a container in the middle of the desert for decades? Was that the day the rats peed in the powder at the ammo factory and nobody noticed? I will continue to shoot older and surplus ammo but…. while striving to know something about its provenance. Fresh, recent ammo is preferable, certainly.