Haven't set off a primer ............................... yet! But I'm sure my time is coming. I did flare some .30 caliber carbine cartridges way too much once, so much in fact, that the crimp die wouldn't even work! (fortunately this was many years ago when I was just learning to hand load). I'm sure I've made others but I can't think of any worth mentioning.
Always wear safety glasses. Primers pack a punch, even without powder. I've crushed a few and when you're staring straight at these press and BANG, it'll rattle you. Especially in a closed garage. Crimping on non semi auto, why bother? Keep all fingers away from between moving press and die at ALL times. Pinched a buddy's finger once, and I've seen far, far worse.
I checked and double checked. Still ended up loading a squib and firing it in my Ruger Blackhawk .45 Colt. I don't know how, but I musta missed charging one case.
I bought a Lee Loadmaster once.. that was a mistake I won't make again.
I once loaded 100 rounds of a light load 45 acp and it wouldn't cycle in my gun so I had to pull most of them
now, if I have any question on a new load, I load a dozen or so and try them first.
Not sufficiently documenting what I was doing. Ended up with some ammo that I had no idea what the powder charges were, etc.
the other is not marking the powder in a measure, walking away for a few days then not remembering what powder it is. Only thing to do is pour it out and start over.
Thankfully, there have been few mistakes since approx 1966, when I started reloading. I am very careful and have always put speed second to safety and accuracy.
I guess the worst error was when I bought a very large pile of .308/7.62 brass that had been fired in machine guns. It was all stretched and over length so I spent many hours getting the brass back into specifications. When it was done, I thought the brass looked pretty good!
After loading a pile of the brass, I stored it in ammo cans then got busy moving to Texas and getting my teaching career running in a new state. That ammo sat for a long time, untouched. Finally, time came to use some of the rounds. A very large percentage of the rounds were cracked at the case neck! These were big, long cracks! True to my "safety first" pledge, I pulled down and salvaged every round!
Some time later, I felt vindicated! I bought a buttload of 30-06 rounds that were made in India. Many of those rounds were cracked at the case neck. Their ammo had the same issues that my .308 rounds had!
I sorted and salvaged the cracked neck rounds and had fun firing the rest.
I've made all sorts:
Runnings a .357Mag case up a .38Spec. seating die was a good one.
Trying to punch out a Berdan primer with your Boxer type sizing die is another.
In my younger days, I'd ocassionally try to seat a primer in a GI brass that hadn't been 'uncrimped'.
Once I was using a primer flipper, and didn't hold it together well enough.
For some reason- I always have lots of spent primers all over the floor that have jumped out of the trash.
To get my 30-40 good primers back, I picked and sorted through about a million dead ones.
The most agravating thing I've done was getting a new .308 sizer die, and 1,000 GI 7.62 NATO brass to compliment my new M1A..
After full length sizing-- every--- single----- one----- of those cases....
.........They were all good clean brass, a good fresh Hornady press, and a new/in the box Brand X die......
I've done all this a million times.... What can go wrong?
Well,,, after I was done cleaning, sizing, and priming all 1,000,,,,,
I loaded one, to double check the seating/length before I went into mass production:
Then,,,,,,,,,,,,, Uh-ohhh......
It wouldn't chamber. Not in the M1A, or a heavy barrel Winchester .308 target rifle.
After a lot of looking, fiddeling, and head scratching, trying to chamber a empty sized brass-
I figured out the sizing die was just defective.
To test my theory,,, I took a old .308 die, ran a brass through it, and that one chambered just fine.
I still have that one die on the shelf over my bench as a reminder of letting down my guard just once.
I drew blood on the .357 sizing deal.
Lots of it.
Daughter was about 8 then.
She made sure I wasn't gonna die, then ran and told her momma that daddy cussed.