If you are wanting to segment into the first half and second half like some posters are doing, then the force in the second half is lower because you start from the velocity at the end of the first half, not from zero. However, I don't see any reason to segment it like this.
I have said momentum is the relevant metric from the beginning. I'm not who brought force up. I've only been discussing force because someone made the claim that the force is equal between long and short barrels because peak acceleration happens early.