Once Fired 5.56x45mm Mystery

[TXTad]

I've been working over a batch of a few thousand once-fired .223 / 5.56 cases that I got from a friend's estate. This was picked up off a police range, so it's mostly been fired in department issued AR-15s. It's a mix of .223 and 5.56, commercial and military headstamps.

This is my first time working over a batch of once-fired .223, though I've done some military surplus 7.62x51 before. My procedure is:

1. Deprime
2. Short wet-tumble with pins and Dawn
3. Swage the prime pockets
4. Full-length resize
5. Trim using a file-type trim die
6. Longer wet-tumble
7. Done!

Step 5 has been surprising. Unlike the batches of once-fired, probably from M60s, military 7.62x51 brass I worked with a while back, less than 5% of these 5.56 cases need trimming. Any thoughts on that?

 

[Dawico]

I have found quite a few of my 223/ 5.56 brass doesn't need trimming even after a few firings.

Makes me happy.

 

[Lonesome Dove]

I've been working over a batch of a few thousand once-fired .223 / 5.56 cases that I got from a friend's estate. This was picked up off a police range, so it's mostly been fired in department issued AR-15s. It's a mix of .223 and 5.56, commercial and military headstamps.

This is my first time working over a batch of once-fired .223, though I've done some military surplus 7.62x51 before. My procedure is:

1. Deprime
2. Short wet-tumble with pins and Dawn
3. Swage the prime pockets
4. Full-length resize
5. Trim using a file-type trim die
6. Longer wet-tumble
7. Done!

Step 4 has been surprising. Unlike the batches of once-fired, probably from M60s, military 7.62x51 brass I worked with a while back, less than 5% of these 5.56 cases need trimming. Any thoughts on that?

It's typical of of some calibers and or brass.

 

[Vaquero]

.223 usually measures shorter than 5.56.
Maybe someone got a batch of reloads.

 

[tekiwap]

I’ve only reloaded 5.56 brass for 77gr in small amounts but yeah, they never needed much trimming. It was maybe enough to clean the rim. Not like the bigger cartridges at all.

 

[Deavis]

You'll find a lot of 223 cases are trimmed originally towards the bottom of the spec at around 1.735". They don't grow enough to hit where most people trim. We trim shorter than most manuals specifically to touch those cases for consistent length.