Lee that's a lot of powder for a 45 Colt with a big bullet like a 255gr. I've used 35gr fffg (volume) under a 250 rnfp bullet and it crunched the powder quite a bit. In fact, i pulled a bullet from one round and I had to scrape the powder out. It was almost like a solid mass, and wouldn't pour.
Liberty and freedom often offends those who understand neither.