Loading for a 223 trying to come up with my OAL. I used the hornady OAL tool, and came up with a 1.854 OG. But if I pressed a little harder I could get 1.869 or so. This method didn't seem real consistent, I'd end up measuring it 10 times trying to come up with something. I worked up a load based on the 1.854 numbers

Today, I decided to size a case until I could seat the bullet by hand and get it back out by hand. I chambered this round letting the rifling press the bullet into the case. I measured this round at 1.950.

So what method is more accurate? I'm thinking the second way would be, and when I thought I was loading .15 jam I was really running a .2 jump?

Now I'm thinking I need to try at bit longer OAL and see if I can tighten up my groups. I seem to be stuck in the .5-.75" groups at 100 yards.