True it will be shorter than say STI, but you should measure to see exactly what your chamber is. My guess is that you could likely go out to 1.150 +/- some, but you will need to check. Take the barrel off and drop a BBI180 down into it and measure the distance from the base of the bullet to flush with the barrel hood, add in the length of the bullet from where it touches the throat. This will determine absolute max COL for your barrel WITH THIS BULLET.
You will absolutely need to load shorter than this figure by at least .01, and perhaps more.
You may also need to adjust for your magazines. So, once you determine a workable COL load do a test loading of the magazines to ensure proper feeding before you start running ammo.