Reloading ammunition or "rolling your own" takes a little a little time but can be a big savings when compared to buying new ammo all the time. However, attention to detail is paramount. A tiny mistake could cause damage to your weapon, injury to the shooter or even death. However, attention to detail can negate these issues. However, the more subtle things may not cause injury or death. More likely you will just run into failure to chamber or fire issues with you home grown ammo.
In this video I show one of the pitfalls of NOT properly resizing the shoulder on a rifle case. Over time my resizing die had backed out of position with the lock nut coming loose. That tiny bit of movement caused the case to not get properly sized and caused the shoulder to not line up with the chamber. The product was a finished round that would not fully chamber and would not fire. Not too mention I had to "motar" the AR15 rifle to get the round out of the chamber.
Now I had a handful of ammo that was useless. The solution was to pull each bullet, pour the powder out and resize the brass. For pulling the bullet I used a collet puller seen in the video. They are inexpensive and simple to use. It's just a time consuming process.
Now when I start a big reload session of rifle ammo, I take the resized case and test it in the rifle I will be using. If the resized brass case does not fit, something is wrong with my sizing die and I make adjustments. This tiny little step will save you hours of suffering.
As always, I'm glad to share and allow you the opportunity to learn from my mistakes.