223 parent cases in a Model 1 upper

[800X]

Guys, I have 2 Model 1 uppers and have been having problems with cartridges seating fully. I sometimes have to let the bolt slam over a cartridge that I dropped into the chamber and I hate to do this.

I have tried 4 boxes now of cor-bon subsonic and this occurs with maybe 25% of the rounds. I also have purchased 1000 primed cases off the web and with these I get maybe 50% failures.

I have measured the empty brass and found that the length is all over the place, but the trimmer set-up I have uses the flash hole to index off of. This means I would have to de-prime all the primed cases I just bought.

I am also somewhat confident that the neck thickness is the real culprit. If I remove the de-priming pin and try to resize the cases I bought, I find they are very tight in the die. If I seat a bullet without resizing, it goes in easy but after resizing it is very tight. This leads me to believe that the necks are just too thick. Keep in mind these cases were supposed to be ready to load.

So, anyone else experiencing the same problems?

Also I am new to reloading and need recommendations on the least expensive quality set up for neck turning. Right now I have a Redding single stage press and dies, and a Lee roto-trimmer. With this in mind, am I going to be stuck buying a new trimmer that can be adapted with a neck turner?

Thanks!!